Public Health Bayer Environmental Science
NEGLECTED TROPICAL DISEASES
Journal No. 19 March 2008
In addition to the major tropical vector-borne diseases like malaria and dengue fever complex, other diseases such as river blindness, leishmaniasis and Chagas are endemic in the poorest regions of Africa, Latin America and Asia. These Neglected Tropical Diseases (NTDs) cause severe disability and suffering equivalent to half the global disease burden of HIV/AIDS. Vector control is a vital strategy in their reduction and elimination.
KEY FACTS
VECTOR-BORNE D
(SELECTION OF THE MALARIA AFRICAN TRYPANOSOMIASIS (Sleeping sickness) Caused by: Protozoan parasites (Trypanosoma) Vectors: Tsetse flies (Glossina) Prevalence: Endemic in rural areas in sub-Sahara Africa. Estimated 50,000 to 70,000 cases per year (WHO).
Caused by: Protozoan parasites (Plasmodium falciparum, P. vivax, P. ovale, P. malariae) Vectors: Anopheles mosquitoes Prevalence: Kills more than 1.2 million people annually (WHO). Over 3000 children die every day from malaria.
LYMPHATIC FILARIASIS (Elephantiasis) Caused by: Parasitic worms (Wuchereria bancrofti, Brugia malayi) Vectors: Mosquitoes Prevalence: Worldwide over 120 million cases in more than 80 countries. LEISHMANIASIS Caused by: Parasites (Leishmania donovani, Leishmania infantum) Vectors: Phlebotomine sandflies Prevalence: Two million new cases annually, an estimated 12 million people infected worldwide (WHO).
CHAGAS DISEASE Caused by: Protozoan parasites (Trypanosoma cruzi) Vectors: Triatomine bugs Prevalence: An estimated 16 to 18 million infected people in Mexico, Central und South America.
ONCHOCERCIASIS (River blindness) Caused by: Parasitic worms (Onchocerca volvulus) Vectors: Black flies (Simuliidae) Prevalence: The world’s second leading infectious cause of blindness. A total of 18 million people are affected worldwide (WHO).
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LYME DISEASE (Borreliose) Caused by: Bacteria Vectors: Ticks (Ixodidae) Prevalence: Most common tick-borne disease in North America and Europe, and one of the fastest-growing infectious diseases in the United States.
DISEASES (VBDs)
E MOS T I M P O RTA N T) *Arbovirus diseases, transmitted by arthropods DENGUE FEVER COMPLEX* Caused by: Flavivirus (Flaviviridae) Vectors: Aedes aegypti mosquitoes Prevalence: The world’s fastest growing vector-borne disease. WHO estimates around 50 million cases worldwide every year.
WEST NILE FEVER* Caused by: Flavivirus (Flaviviridae) Vectors: Mosquitoes (Culex) Prevalence: Increasing outbreaks in the Western Hemisphere (including North America).
CHIKUNGUNYA* Caused by: Alphavirus (Togaviridae) Vectors: Aedes mosquitoes (Ae. aegypti, Ae. albopictus, Ae. furcifer, Ae. africanus) Prevalence: Increasing dramatically especially in regions around the Indian Ocean.
YELLOW FEVER* VIRAL ENCEPHALITIDES* (e.g. Japanese Encephalitis, La Crosse E., Tick-borne E., Murray valley E., St. Louis E., Equine E.) Caused by: Flavivirus (Flaviviridae), Alphavirus (Togaviridae), Bunyaviridae Vectors: Mosquitoes (Culex, Aedes) Prevalence: Viral Encephalitides have a global distribution – from Japan to the United States.
Caused by: Flavivirus (Flaviviridae) Vectors: Mosquitoes (Aedes, Haemogogus) Prevalence: Over the last 20 years the number of yellow fever epidemics has risen and more countries are reporting cases. Around 30,000 deaths every year (WHO).
TICK-BORNE HEMORRHAGIC FEVER* Caused by: Nairovirus (Bunyaviridae) Vectors: Ticks (Ixodidae) Prevalence: Increasing problem e.g. in the states of the former Soviet Union, Northwestern China, Central Asia, Eastern and Southern Europe, Turkey, Africa, the Middle East and the Indian subcontinent.
Available as poster on the enclosed Public Health CD-ROM
CONTENT
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Editorial Background
Global plan to combat NTDs
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COVER STORY
Vector-borne diseases are transmitted to humans by various insects and ticks. Natural water reservoirs are a common breeding place for many of them.
Vector-borne diseases
Affecting more than a billion people
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NEGLECTED TROPICAL DISEASES
NTDs
Causing poverty and suffering
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Chagas disease in the Americas
Combatting a silent disease
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by Felipe Guhl
Arboviruses
Increasing threat Rift valley fever and dengue fever in Saudi Arabia
Vector control operations
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by Suleiman Mohammed al Seghayer
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CONTENT
Dengue
Casa Segura – a new approach for vector control by Barry Beaty and Lars Eisen
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Leishmaniasis
An underestimated cause of suffering
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by Michele Maroli and Giancarlo Majori
Canine leishmaniasis
Protecting dogs against sandfly bites
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by Norbert Mencke PA R T N E R S H I P S
Increasing role of foundations working against global inequity
Catalysts for global health efforts New private-public initiatives
Generating complementary actions
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NGO
CORE Group: Network of NGOs
Coordinating efforts to improve children’s health NGO Profile: MCDI
Developing health infrastructures Health care reaching Amazonian Indians
Mosquito nets for the Yanomami Notes CD-ROM Cover photo: Iconotec PUBLIC HEALTH JOURNAL 19/2008
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46 49 52
EDITORIAL
Dear Readers, I am pleased to say Public Health Journal No. 19 addresses a theme that is all too often overlooked in global issues and media reports: neglected tropical diseases (NTDs). Naturally, the fight against malaria requires our maximum engagement, and considering it claims over a million lives every year, has the highest priority. But PASCAL HOUSSET Head of diseases such as river blindness, Chagas, or leishmaniasis (to name Bayer Environmental Science only a few) demand just as much attention. Ultimately, NTDs affect more than one billion people – many of them living in conditions of extreme poverty. It must be our social responsibility to give these people a chance to live a healthy life. In addition, NTDs are increasing again in areas where they were once under control, as well as starting to spread to previously unaffected countries. This not only reflects factors such as lapsed infrastructures, but also climate change and international trade and travel. In this issue we cover current initiatives of the WHO and others focusing on NTDs with the goal of reducing the burden of these diseases in a responsible manner. Our cover story outlines the importance of vector control at all stages of the cycle – a strategy of integrated vector management. Then, following the tradition of our Journal we present several case studies describing methods to combat certain NTDs, and look at examples in Latin America and Saudi Arabia. Our authors present the new approach of “Casa segura” and discuss how important indoor residual spraying and insecticide-treated bednets, curtains and other materials are in the control of leishmaniasis, dengue and other vector borne diseases. In addition to the main theme of neglected tropical diseases, this edition also highlights the increasing role of foundations and celebrities in the global fight against poverty-related diseases. We would also like to report on a courageous private initiative to help Amazonian Indians.
We wish you pleasant reading.
Pascal Housset
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BACKGROUND
WHO
Global plan to combat NTDs Reducing the negative impact of neglected tropical diseases (NTDs) on the health and social and economic well-being of already impoverished communities can clearly contribute to achieving the Millennium Development Goals. Already millions of people have benefited from interventions against these infections, but many more still suffer from pain, disability and poverty due to NTDs. The WHO Department of Control of Neglected Tropical Diseases has compiled a Global Plan to combat these diseases. sually overshadowed by the major diseases HIV/AIDS, tuberculosis and malaria, neglected tropical diseases have inflicted suffering on humanity for thousands of years. Today, they affect more than one sixth of the population. Recently, the WHO and its partners formulated the challenges, goals and targets, strategic areas for action and framework for implementation, monitoring and evaluation of a global strategy to combat NTDs (see links below). Effective, inexpensive control tools, mostly drugs, are already available for a large group of NTDs. These “tool-ready” diseases include leprosy, yaws, trachoma, river blindness, filariasis, onchocerciasis, schistosomiasis and soil-transmitted nematodes. Used on a large-scale, these tools are able to control, prevent and possibly eliminate these diseases. The major task here is to extend this into preventative “quasiimmunization”, multi-disease, interprogram approaches. Successes to date include reducing leprosy from 14.5 million cases in 1985 to less than a million today. Also, the Guinea worm eradication program reduced the number of people infected with the disease in the early 1980s from about 3.5 million in 20 endemic countries to around 10,000 cases in nine endemic countries in 2005. PUBLIC HEALTH JOURNAL 19/2008
A second group of NTDs are defined as “tooldeficient” diseases, because apart from preventive vector control measures, simple, safe and costeffective tools still do not exist for large-scale prevention of irreversible disability or death caused by these diseases. This group includes most of the vector-borne NTDs, such as African trypanosomiasis, Chagas disease and leishmaniasis. Apart from systematic case-finding and disease management at an early stage, the only other tool is vector control to prevent transmission. The framework for controlling vector transmission is integrated vector management (IVM). The major tasks here are strengthening the national capacities of countries endemic for vector-borne disease to apply the principles and approaches of IVM and the safe and effective management of public health pesticides. The IVM infrastructure needs to be integrated into existing health services and linked with other sectors (agriculture, irrigation, environment, public works, information and education). These are essential components of vectorborne NTD prevention and control. More WHO: www.who.int/neglected_ diseases/ WHO Global Plan to combat neglected tropical diseases: http://whqlibdoc. who.int/hq/2007/WHO_CDS_NTD_ 2007.3_eng.pdf
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Photo: Michelle Cornu
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COVER STORY
Vector-borne diseases
Photo: Michael Bรถckler
Affecting more than a
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billion people
Tropical disease vector control programs in the midtwentieth century proved highly efficient. But as the incidence of vector-borne diseases (VBDs) dropped, so did funding, technical expertise and existing infrastructures for implementing vector control. Now many VBDs have re-emerged or spread to new areas to inflict a terrible and unacceptable burden on public health.
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S
even of the 10 diseases with overwhelming public health and socioeconomic importance targeted by the World Health Organization are VBDs. The morbidity and mortality associated with VBDs (malaria, leishmaniasis, filariasis, onchocerciasis, Chagas, African trypanosomiasis, dengue) is immense: they are responsible for about 17% of all infectious diseases worldwide. Unfortunately, vaccines for most of these diseases are not available, and for the most part, probably lie far in the future. Definition of vector-borne diseases A vector-borne disease (VBD) is caused by the active transmission of a pathogen (virus, bacteria or parasite) by a vector, usually an insect or a tick. In contrast to passive transport, such as a fly carrying bacteria on its tarsi, VBD transmission is active, often involving blood-sucking transfer routes. In the case of MALARIA Plasmodium parparasitic pathogens, the asites transmitted by female vector also plays an Anopheles mosquitoes infect important role in the lifepeople worldwide, killing over a million, mostly children, cycle of the parasite. For each year. example, malaria-causing Plasmodium need mosquitoes for one part of their lifecycle then complete the cycle in humans. Malaria is a well-known tropical disease, but a number of neglected tropical diseases (NTDs) are also vector-borne, although not all. For example, the parasitic disease schistosomiasis, where the essential intermediate hosts, aquatic snails, do not actively transmit the parasite further, is not defined as a VBD.
• accelerating population growth • major demographic changes resulting in rapid or unplanned urbanization • a decline in public health and vector control programs • erosion of expertise in medical entomology and vector biology • loss of pesticides due to the emergence of resistance in vector populations and social resistance to the use of some pesticides • no new active ingredients for adult vector control detected for many years • changes in animal reservoirs • human displacement due to wars or natural disasters • land use trends conductive to the spread of vectors carrying disease • societal and behavioral changes such as the emergence of the “throw-away society” • often no vaccines, and expensive, unavailable, or spreading resistance to drugs for treatment • shift of focus from VBDs to TB and HIV/AIDS,
It is extremely frustrating that VBDs such as dengue and malaria are resurging in areas where they were previously successfully managed by vector or disease control programs. This VBD resurgence is due to complex interactions between numerous factors, including: 8
Photo: Michelle Cornu
Factors leading to VBD resurgence
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including political commitment of donor (industrial) towards recipient (third world) countries • loss of pesticides because of non-registration issues in northern countries. Transmitted to humans by various insects (especially mosquitoes) and ticks, the resurgence of VBDs is also occuring in the northern hemisphere with West Nile fever in North America and Southern Europe, Chikungunya in Italy and Leishmaniasis in the Mediterranean region. This highlights the urgent need for new tools and approaches to controlling these vectors. More targeted pro-active strategies Large-scale indoor residual spraying (IRS) and space spraying have been employed for many years against malaria and dengue, and coincidentally controlled leishmaniasis. However, such operations are expensive, labor-intensive, and
require suitable infrastructures, supplies of insecticide, spraying equipment, trained personnel and funding, particularly over a long-term to be sustainable. These operations need to take local conditions and environmental impact into account not to overlook, or indeed accelerate, emerging insecticide resistance in the vectors. While reactive and rapid large-scale actions are still necessary during epidemics or outbreaks of disease, a more targeted approach is preferable. This involves a switch from personal protection to pro-active, long-term vector control. In addition to specific IRS of dwellings and animal shelters, other strategies such as widespread use LEISHMANIASIS Prevalent in North Africa and the Middle of insecticide-treated nets East, with animal reservoirs (ITNs) and source in southern Italy, the protoreduction are important. zoan parasites transmitted by This includes physically sandflies cause chronic disremoving or treating abilities and disfigurement. breeding sites with biological or insecticidal larvicides to control immature insect stages. VBDs are primarily linked to poverty and poor housing. Water supply, sanitation, urban and rural development as well as refuse disposal management are necessary to prevent creating new vector breeding sites. Improvements in housing should aim to limit vector access to healthy inhabitants or to already infected people, particularly in hospitals, to prevent further transmission (Casa Segura). Long-lasting insecticide-treatments Recently, new incentives such as the Millennium Development Goals stimulated renewed efforts to control malaria. One result was the increasing large-scale use of the first major new tool for
ALMOST 10 MILLION CHILDREN, mostly in Africa, Asia and the Middle East, never reach their fifth birthday. Many die due to vector-borne diseases. Others survive, but may be disabled or disfigured for life.
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vector control in 50 years – insecticide-treated bednets (see: PHJ No. 17). Technologies to produce long-lasting insecticide treatment of bednets led to investigating other materials. Such impregnated materials promise not only improved control of malaria transmission, but also other VBDs such as leishmaniasis, lymphatic filariasis, Chagas disease and dengue (see: Casa Segura, page 26). Other developments include controlled release larvicides for chikungunya and dengue, and long-lasting insecticidal traps for the tsetse fly to combat African trypanoELEPHANTIASIS somiasis. Skin or clothing (lymphatic filariasis) repellants as well as Socially stigmatizing insecticide-treated collars disfigurements caused by for dogs are used to helminth parasitic worms burden the lives of millions combat leishmaniasis (see: of people. Mosquitoes Leishmaniasis, page 32, pass on the parasite. and canine leishmaniasis, page 38). Repellants for dogs represent an example of an additionally strategy: treating animal reservoirs of VBDs.
lasting insecticide treated bednets from vulnerable groups to total population cover can switch personal protection into part of a sustainable strategy for vector control and ultimately elimination. It is encouraging that traditional support from the Global Fund, World Bank, WHO, UNICEF, PMI, and more, is being joined by commitments from foundations, private philanthropists, celebrities, airlines, etc. (see page 40) to help fund more long-term strategies. Support from all levels International and national support are of course still essential for providing technical expertise, training, education and planning national control policies and local programs. Monitoring, surveillance and evaluation are essential to check the efficacy of control operations, possible re-infestation, subsequent vector population levels, and the emergence of insecticide resistance (see: PHJ No. 18). Such activities require collecting data with the help of international and national organizations, NGOs and community groups, as well as cooperation with research institutes and other scientific departments for up to date laboratory analyses (see: CORE + MCDI, page 46). Private sector social marketing and partnerships, committed to
Personalized protection The emphasis of these recent strategies is towards personalized protection measures that best suit specific situations, living conditions and people’s behavior in the communities affected by disease. This requires monitoring, organization, education and action operating at the level of district, municipality or local communities, i.e. from the bottom up – in contrast to earlier programs organized and run from the top down. Such social mobilization and community responsibility will not only be more likely to have a sustainable effect, but also be more cost-effective in the longterm than large-scale initiatives. However, these can be neither cost-effective nor sustainable with limited target and time-span projects, but need long-term commitment and funding. For example, increasing supplies of long10
Definitions Control: Reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level Elimination: Reduction to zero of incidence of infection (or disease) caused by a specific agent in a defined geographical area Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent Extinction: The specific infectious agent no longer exists in nature or in the laboratory Source: International Task Force for Diseases Eradication, WIN - Working Group on Scalable Malaria Vector Control
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RIVER BLINDNESS (onchocerciasis) Caused by helminth parasitic worms, this disease can be controlled by combatting the black fly vector and by medical treatment.
CHAGAS Symptoms caused by protozoan Trypanosoma parasites indigenous to Latin America may take years to appear. The parasite is transmitted by Triatomine (“kissing”) bugs.
Photos: Michael Böckler
POVERTY, LINKED TO POOR HOUSING, water supplies and sanitation are major factors contributing to the spread of vector-borne diseases.
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DENGUE These arbovirus infections are increasing dramatically in the Americas, India and Asia due to the Aedes mosquito’s preference for breeding in domestic areas. Only symptomatic treatment exists.
All vector photos in this article and on back cover by: Reiner Pospischil
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COVER STORY
corporate social responsibility (CSR), provide opportunities worldwide for supporting community-based programs, as demonstrated by initiatives to promote insecticide-treated bednets to combat malaria. Finally, funding by voluntary organizations, government aid, private-public initiatives, NGOs, foundations and charities can make all of these activities feasible (see: partnerships, page 40). Combining targets It is clear that one vector control approach can target a number of diseases. Different disease vectors may share the same habitat or behavior, or the same vector may transmit different diseases, such as dengue, yellow fever and chikungunya. So single interventions can target several diseases at the same time, such as indoor residual spraying (IRS) against malaria, dengue and leishmaniasis. This can make the most effective use of limited financial and human resources. Vector control programs can also be combined SLEEPING SICKNESS (African with other public health trypanomosiasis) Endemic in initiatives such as vaccirural areas of Sub-Sahara Africa, nations against childhood the protozoan Trypanosoma diseases, ante-natal care parasites are transmitted by the tsetse fly, which can be and child health protargeted by traps. grams. Environmental programs addressing land use, pollution and refuse disposal can link up with vector source reduction, and farming groups can help with vector management associated with agricultural practices. In contrast, constructions of dams or other major landscaping that may increase vector breeding grounds, should integrate public health specialists for vector-transmitted disease protection. All these strategies offer a new combined approach to vector control in a sustained, ecological and economical manner. This approach is called integrated vector management (IVM). 12
Integrated vector management (IVM) The WHO defines IVM as a decision-making process for the management of vector populations, so as to reduce or interrupt transmission of vector-borne diseases. Characteristic features of IVM include: • Selection of methods based on knowledge of local vector biology, disease transmission and morbidity; • utilization of a range of interventions, often in combination and synergistically; • collaboration within the health sector and with other public and private sectors that impact on vector breeding; • engagement with local communities and other stakeholders; • a public health regulatory and legislative framework; • rational use of insecticides; • good management practices. An IVM approach takes into account the available health infrastructure and resources and integrates all available and effective measures, whether chemical, biological, or environmental. This strategy also serves to extend the useful life of insecticides and drugs by reducing the selection pressure for resistance development.
Integrated vector management Starting from the bottom up, this approach first assesses local vector species, incidence rates and infection. Information about community life-style, housing, local ecology and land use are combined with available knowledge about the biology of the vector – breeding, transmission, preferred habitats. All these aspects are evaluated to work out the most economical, effective and feasible combination of vector control methods. An integrated vector management strategy is therefore designed
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COVER STORY
Photo: Michael BĂśckler
RECENT VECTOR CONTROL STRATEGIES, such as IVM, aim to integrate measures that best suit specific living conditions and people’s way of life in the community.
to specifically address local problems and situations and optimize knowledge and resources. Emphasis is on personal protection methods, locally suitable environmental management, biological or larvicidal source reduction and limiting human-vector contact. The aim is to control, manage and monitor VBDs at all stages of disease incubation and transmission. One of the conclusions should be that even within IVM the judicious use of chemicals is one of the cornerstones of effective and sustainable vector control, including the use of suitable and approved products in the right manner. This means anticipating the development of resistance. So it requires resistance prevention schemes or resistance management strategies, since it cannot be predicted that we will have major new chemical classes in the near or mid-term future. Vector control interventions should be decided on at the lowest possible administrative level, i.e. closest to the communities affected by the disease. But such decisions should be supported by the best information and technologies currently available, as discussed above. Thus integrated vector management also seeks to integrate national and international health sector infrastructures and resources, as well as collaborate with relevant public and private sectors. Already a number of public and private initiatives have demonstrated PUBLIC HEALTH JOURNAL 19/2008
how these can work together to reduce vectorborne diseases, resulting not only in improved health but also providing economic benefits (see: MCDI, page 49). Endorsed by the WHO, integrated vector management is seen as a vital component to help global efforts achieve the Millennium Development Goals. IVM could play a major role in reducing child mortality, improving maternal health, increasing economic productivity while helping sustain the environment. CONCLUSION Few vector control programs implement integrated vector management strategies effectively. Too many programs concentrate on single-issue campaigns and quick-fix solutions. As vector control tools, scientific knowledge and new methods emerge, integrated vector management strategies offer a way to optimize all these into an economical, sustainable approach to combat vector-borne diseases. Article on the enclosed Public Health CD-ROM
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NTDs
Causing poverty and suffering The impact of NTDs on child health, pregnancy and worker productivity promotes poverty by causing economic losses amounting to billions of dollars. Controlling these chronic, debilitating and disfiguring diseases will not only relieve suffering for millions of people but will help break the poverty trap.
M
ost chronic infections classified as neglected tropical diseases (NTDs) are little known in industrialized countries. Yet worldwide at least 1 person in 6 suffers from one or more of these parasites or infections – although due to few reliable statistics this number may be much higher. Since these diseases primarily affect the poorest populations in the developing world, they tend to have a low profile in public health issues. Life-long disability and disfigurement The 14 diseases currently listed as NTDs include protozoan, helminth, bacterial, fungal or ectoparasitic infections caused by unsafe water, inadequate housing and poor sanitation. Such conditions are not only linked to low-income or lower middle-income economies, but also to rapidly expanding urban slums, increasing “disposable” consumerism, dams and irrigation schemes and population displacement due to conflicts or natural disasters. Children are the most susceptible to infections, which can result in life-long physical pain and disability. Some NTDs such as leishmaniasis and lymphatic filariasis (elephantiasis) cause gross disfigurements leading to discrimination and exclusion from society. Others cause acute infections with severe symptoms that can be fatal. Programs focusing on NTDs Neglected tropical diseases are now receiving more attention, with recent successes in preventing
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or eliminating some of them (e.g. river blindness, trachoma and leprosy) providing impetus to scale up programs to combat NTDs. For example, the World Health Organization (WHO) Department of Control of Neglected Tropical Diseases supports Member States and partners in reducing the negative impact of NTDs. Together with the Centers for Disease Control and Prevention (CDC), the WHO recently listed six of these diseases (leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths, and trachoma) as “targets of opportunity” for complete eradication. Since 1975, the WHO has co-sponsored an independent global program of scientific collaboration concentrating on a range of major poverty-related diseases. This Special Programme for Research and Training in Tropical Diseases (TDR) is also sponsored by the United Nations Children’s Fund (UNICEF), the United Nations Development Programme (UNDP) and the World Bank. TDR aims to coordinate research and development of new approaches, as well as support local training in implementing these approaches to diagnosing, treating, preventing and controlling NTDs in endemic countries. The Neglected Tropical Diseases Coalition (NTDC) was established in 2005 to provide a forum for organizations to work together to integrate and coordinate NTD control efforts. Composed of individual disease alliances, international agencies, corporate partners, academic institutions and non-governmental organizations,
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“Often, populations most affected by neglected tropical diseases are also the poorest and most vulnerable and are found mainly in tropical and sub-tropical areas of the world.”
Photo: Corbis
www.who.int/neglected_diseases
NTDC aims to coordinate implementation and resource mobilization efforts in industrial countries and support disease management in endemic countries in efforts to improve the health and social well-being of affected communities. Vector-borne NTDs A number of NTDs are transmitted by insects: black fly is the vector for river blindness (onchocerciasis); tsetse fly for sleeping sickness (African trypanosomiasis); sandfly for leishmaniasis; “kissing bug” for Chagas disease; and mosquitoes for lymphatic filariasis (see coverflap). Elimination strategies have been effective for black fly, recovering over 25 million hectares of infested land, and for tsetse fly using hanging traps. However, for the others, effective vector control remains a priority to reduce or stop transmission.
CONCLUSION Vector control plays a vital part in the prevention of vector-borne diseases, not just malaria, but a range of neglected tropical diseases. Strategies for sustainable, cost-effective, less hazardous and more accessible vector control tools and technologies, including sound management of pesticides, are essential. This is the aim of the WHO Vector Control and Management unit, which promotes and provides technical support for integrated vector management (see page 12) to reduce the health burden caused by vectorborne diseases. More WHO: www.who.int/neglected_diseases/ NTDC: www.neglectedtropicaldiseases.org/ TDR: www.who.int/tdr/
Article on the enclosed Public Health CD-ROM
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Chagas disease in the Americas
Combatting a silent disease Various estimates indicate that some 20,000 lives are lost annually in the Americas as a result of Chagas disease. But the true scale of the disease is difficult to assess because chronic stage symptoms may develop years after infection. Vectors for the disease-causing parasites are triatomine bugs, and these are ideal targets for control programs to prevent transmission.
A
merican trypanosomiasis is a highly complex Thanks to sustained vector-control and blood zoonosis, endemic to South America, Central transfusion monitoring in several countries of the America and Mexico. A wide variety of strains of region, the incidence of Chagas disease has the parasite Trypanosoma cruzi infect 150 different decreased dramatically over the last 15 years (see species from 24 families of domestic and wild table: Epidemiological parameters). animals. Chagas disease arose by chance when humans came into Underestimating the scale contact with the natural foci and of the problem caused ecological imbalances, forcing infected triatomine bugs to occupy In general, control programs have human housing. The settlement focused their budgets and strategies process took its course and these on the elimination of vector insects insects found shelter and sufficient closest to human habitats. Some food in human and domestic animal resources have been allocated to blood. This is how humans became combating the disease, which gives an active participant in the Chagas it a certain status within health care The author: disease epidemiological chain. institutions. However, attitudes are FELIPE GUHL passive due to the lack of knowledge Director Tropical Diseases Associated with poverty about the scale of the disease, i.e. Research Centre, University of the Andes, and poor housing detecting cases, and only people who Bogotá, Colombia. have developed concrete symptoms WHO, Expert One fourth of Latin America’s are recorded. Thus, all other cases Advisory Panel on population is at risk of contracting (over 70%) of people infected with Parasitic Diseases this infection, taking into account the T. cruzi remain in the background. (Trypanosomiasis) geographic range of vector insects These are people who show no and multiple reservoirs involved in apparent symptoms, thus decreasing the various cycles of transmission. The clinical perceptions of the true range of the disease. This history of Chagas disease indicates that this is a reinforces the concept of a neglected disease and systemic and chronic parasitic infection that causes causes underestimates of business interests in severe heart disease (cardiomyopathy) or dilation this disease. of the digestive tract (megacolon and megaesophagus) in 20 to 30% of infected patients. It is In fact, various estimates indicate that Chagas associated with poverty and poor housing disease accounts for some 20,000 deaths annually conditions, and is widespread mainly in rural areas in the Americas. As a poor people’s disease, of the entire Latin American continent. Chagas occurs in regions where it coexists with 16
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Photo: Felipe Guhl
CHAGAS DISEASE remains a serious obstacle to health and economic development in Latin America, especially for the rural poor. The photograph shows a human dwelling in an endemic area for Rhodnius prolixus in Guatemala. Here, the infestation index was over 42% before residual insecticide spraying.
other more obvious and less silent diseases. This is why it frequently remains undetected as a health issue. More than any other parasitic disease, Chagas is associated with economic and social development. Triatomines and the disease they transmit will remain in Latin America as long as there is inadequate housing, frequent population migration, colonization fronts and rapid urbanization.
Perfect targets for control Enzootic transmission in the wild will continue and, therefore, so will human infection. This is an epidemiologically limiting factor that points to the impossibility of eradicating Chagas disease. The equation also includes the wide diversity of reservoirs as a limiting condition, which means it is impossible to destroy all sources of infection.
Epidemiological parameters (based on 21 countries) 1990
2000
2006
Human infection cases
30 million
18 million
15 million
New cases per annum
700,000
200,000
41,200
100 million
40 million
28 million
Population at risk
DESPITE CONSIDERABLE REDUCTIONS in morbidity over the last 16 years, Chagas disease remains a serious problem in Latin American countries.
Source: TDR/WHO, PAHO
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With so many limitations it would seem that Chagas disease is not controlable at all. However, some characteristics specific to triatomines mean that this is not so. These insect populations are very stable and recover very slowly. Furthermore, domestic populations of a particular species have little genetic variability, which makes them more vulnerable to insecticide action. As practical experience has shown, domestic triatomine populations are a perfect target for control measures and can be eliminated. However, given the lack of resources and continuity in control programs, it is improbable that the rapid elimination of all populations is viable. Control strategies and planning
definitive measure, and after the residual-action period of the insecticide comes to an end, a second spraying cycle is required, which is also a temporary measure. Obviously, reinfestation of housing is possible, and a parallel entomologic monitoring program is required. Furthermore, all actions need to be sustainable over time. Clearly, the use of one control method does not exclude the use of others. Chemical control should be considered a complement to improving rural housing and reorganizing the peridomiciliary (surrounding) area where native vector insects may exist and then reinfest housing with relative ease. These actions require active coordination with social organizations and local government development councils.
Lastly, during the monitoring The main vector-control method for phase, trained personnel visit the Chagas disease is spraying housing houses to check for potential Rhodnius prolixus with residual-action insecticides. As reinfestation foci. The factors secondary measures, rural environment determining reinfestation, include demographic management and administration are combined and environmental variables on different spatial with improving rural housing. The insecticide- scales, as well as the detection of residual foci based fight against vectors is efficient and has with very low insect density. These aspects require been proven to interrupt transmission. This is more in-depth research with a view to optimizing because the most anthropophilic species, i.e. those control operations. best adapted to human housing, are susceptible to the application of such insecticides. Control A successful model programs have been structured in three successive phases: preparation, mass attack and monitoring. Sub-regional approaches adopted in American countries to deal with the Chagas disease problem The preparation phase includes geographic are based on entomological and epidemiological surveys, mapping and collecting data on infestation criteria. However in general, their objectives are to in homes and surrounding areas, as well as eliminate vector-borne and parasite blood community education, information and obtaining transfusion transmission and to develop local authority consent. intervention strategies according to the criteria mentioned above. For example, the Southern Cone In the following mass attack phase, professional country initiative was launched in 1991. This teams travel to infested areas and apply insecticides involves concerted action of national governments in homes and surrounding buildings, following in the region, focusing mainly on interrupting standardized procedures. Insecticides are an vector transmission by Triatoma infestans and immediate control measure that helps the blood transfusion transmission of Chagas disease population avoid contact with the vector insects in Argentina, Brazil, Bolivia, Chile, Paraguay for approximately 6 to 8 months. This is not a and Uruguay. 18
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Geographical zones of Chagas vectors
Central American Countries Initiative (1997) Rhodnius prolixus Triatoma dimidata Triatoma barberi Rhodnius pallescens
Andean Countries Initiative (1997)
Amazon Region Initiative (2004)
Rhodnius prolixus Triatoma dimidata Triatoma maculata Rhodnius ecuadoriensis
Rhodnius brethesi Rhodnius robustus Panstrongylus geniculatus
Southern Cone Countries Initiative (1991) Triatoma infestans Triatoma brasiliensis Triatoma sordida Panstrongylus megistus 0 1000 km
THE MAP SHOWS the geographical zones corresponding to the range of the various vector insects, and the countries that have developed initiatives, with their respective launch dates.
Years later, the governments of the other countries developed their own initiatives and commitments, taking into account the eco-epidemiological considerations. A map shows the epidemiological mosaic that served as the basis for various continental initiatives to combat Chagas disease (see map: Geographical zones).
populations. This goal should continue with actions to prevent the re-establishment of domestic populations by monitoring geographic reinfestation patterns using geographic information systems, selective action in isolated cases of reinfestation and mass intervention for group reinfestation.
Currently, Argentina, Bolivia and Paraguay, the countries forming the Andean initiative (Colombia, Ecuador, Peru and Venezuela), the Guyanas, all the Central American countries and Mexico are implementing vector-control programs at various paces. Due to both the wide variety of triatomine insects serving as vectors for the parasite and their different biological behavior, new vector control strategies are needed, especially if we take into consideration those species that occur in peridomiciliary areas and in the wild. This situation points to the need for extending such strategies to combat the disease.
Control and monitoring must be implemented in parallel, taking into account the need for ongoing monitoring of the ever-present risk imposed by wild triatomine populations, which are a major factor in the housing reinfestation process.
Vector control goals
Operational needs are directly related to biological characteristics of triatomine insects. Therefore, we need to consider the fact that different transmission patterns exist in different areas. This means that the severity of the transmission risk will be different, and each case must be dealt with in a specific manner according to the particular characteristics of each insect, i.e. a distinct treatment will be used for each situation.
The primary goal of vector control programs is to eliminate all existing domestic triatomine
Triatoma infestans, the main vector in the Southern Cone countries for example, was selected as a
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Distribution of Triatoma infestans Potential maximum of T. infestans
Current distribution of T. infestans
Current estimate 913.485 km2
Predicted maximum 6.278.081 km2
candidate for elimination. This took into consideration precise details about its biological characteristics and vectorial ability, as well as its recognition as an important public health vector, the availability of intervention tools and social and political commitment (see map: Distribution of Triatoma infestans). All these actions helped interrupt transmission over extensive regions on this continent. Brazil, Chile and Uruguay, for example, have been declared free from transmission by Triatoma infestans, the main domestic vector in these countries, with the resulting reduction in human cases (see table: Epidemiological parameters, page 17). Similar arguments have been used for Rhodnius prolixus in Central America, with very significant success in Guatemala and Honduras, although not in Venezuela and Colombia where R. prolixus also occurs in wild foci and has greater genetic variability. 20
AN ESTIMATE of the maximum range of Triatoma infestans in the Southern Cone countries (Gorla, D. 2002) and the current range after implementing control programs.
Challenges for the future Other species, such as Triatoma dimidiata, have a very wide range, including numerous types of habitats: in the wild, in peridomiciliary and domestic areas. T. dimidiata is also considered to be a candidate species for elimination or reduction of population numbers, whichever applies. Specific control strategies should be implemented with other wild habitat species, such as Panstrongylus megistus, Triatoma brasiliensis and Triatoma pseudomaculata in Brazil, Rhodnius pallescens in northern Colombia and Panama, and other species including Triatoma pallidipennis in Mexico. In Venezuela, Colombia, Ecuador and northern Peru, significant similarities between the main vector species help in dealing with them in a similar manner across the region, based on strategies that have proven successful in other
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similar epidemiological circumstances. In epidemiological terms, the most significant vector species in the Andean Pact Region is Rhodnius prolixus, known throughout extensive regions of Venezuela and Colombia, and also in regions of Central America. Basically, this is a domestic species of Triatominae derived from palm tree populations. Some particular situations in different geographic areas of the continent need to be given consideration when developing new control strategies. For example, there are recent records on the extensive range of R. prolixus populations in the wild, associated with palm trees in the Colombian-Venezuelan plains, which may play an important role in domestic housing reinfestation processes. This particular case deserves special attention in the development of new control techniques and strategies. Other species such as Triatoma dimidiata, which is widespread in Mexico, Central America, Colombia and Ecuador, cannot be used as viable candidates for local elimination because wild populations also occur in many areas, particularly in shady and rocky habitats. Here an abundance of possums and other small mammals lead to very widespread dissemination. The Argentine-Bolivian region of Gran Chaco is a major challenge with regard to wild populations of T. infestans and its dissemination. Still a lot to be done Chagas disease control strategies are based on interrupting vector transmission, systematic screening of blood donors in all endemic countries, detecting and treating congenital transmission and administrating treatment to acute cases and to children under 16 years of age. Several challenges remain, and there is a lot of work to be done: • How to ensure control program continuity and sustainability in those regions where domestic vectors have been eliminated successfully. • How to face the problem of secondary vectors that may reinfest houses which have been treated with insecticide.
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CHAGAS BUGS Belonging to the order Reduviidae, the triatomine or hematophagous assassin bug family includes the most common insect vectors for Chagas disease: Triatoma infestans, T. dimidiata, T. brasiliensis, T. pseudomaculata, T. pallidipennis, Rhodnius prolixus, R. pallescens and Panstrongylus megistus. • How to control wild and peridomiciliary vectors representing a high risk factor of parasitic transmission to humans. Finally, human migrations are an important risk factor in transmitting T. cruzi infection by blood transfusion, if we consider mass migrations of infected individuals from endemic rural areas to urban areas. Migrations to the United States of America and Europe and other continents are particularly important in this respect. CONCLUSION It is ethically not acceptable to condemn rural populations to ongoing cohabitation with domestic triatomines, when strategies and tools to eliminate them have been extensively tested and justified both technically and economically. The challenge is to improve, extend and adapt vector control strategies, including continuous monitoring for reinfestation, to have a sustainable effect in combating Chagas disease. See: History – Chagas’ new disease (page 58) Article on the enclosed Public Health CD-ROM
Bayer HealthCare is providing 2.5 million tablets of the drug Lampit® (active agent: Nifurtimox) for free, as well as additional financial funding, to support the World Health Organization (WHO) in the fight against Chagas disease. 21
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Arboviruses
Increasing threat The hosts of arboviruses are animals and humans, but they can only be transmitted from infected individuals by biting, blood-sucking insects and ticks. In infected people these viruses cause a variety of diseases, with symptoms ranging from mild fever and rashes to serious, potentially fatal meningitis, encephalitis and hemorrhagic complications.
example, mosquito-borne yellow fever, an acute arboviral disease associated with hemorrhagic symptoms and liver function failure, emerged as a devastating problem among workers brought in to build the Panama Canal in the early 1900s. An effective vaccine was developed later, but despite this yellow fever has re-emerged as a major health problem in many African and South American countries today. In 2001, the WHO estimated 200,000 cases of yellow fever among nonvaccinated populations, with around 30,000 deaths every year.
More recently, chikungunya outbreaks spread through India and Indian Ocean Islands (see Public Health Journal No. 18). The mosquitoborne disease also appeared for the first time in rboviruses are a group of viruses transmitted Italy – this time implicated with climate change between hosts by insects and ticks (see page 56). Increases in West Nile virus, (arthropods), hence their name: arthropod-borne St. Louis encephalitis virus and Rift valley virus, viruses or arboviruses. Ticks and biting flies including fever outbreaks in Saudi Arabia (see (particularly mosquitoes) ingest the blood of an page 24), have also been attributed to weather infected host and pass on the conditions. Warmer, wetter virus at the next blood meal weather not only promotes Diseases caused by (for vectors and diseases see faster virus replication but also arboviruses include: coverflap). Arbovirus hosts are accelerated insect growth, Chikungunya, often animals such as deer or resulting in insects having a birds, where humans are a subthinner gut wall, which in turn dengue fever, optimal host. Then the disease is easier for the virus to Rift valley virus, is normally not transmitted penetrate. West Nile fever, further from infected people, e.g. West Nile virus, where the Human host for dengue yellow fever, animal reservoir determines the various encephalitis spread of infection to people. Of all the insect-borne viruses, diseases and tick-borne But some viruses have adapted dengue has re-emerged as one extremely well to humans, such of the major threats to human hemorrhagic fever. as dengue. If humans are a health. Since humans are the major host for virus propagation, the disease can main host for these mosquito-borne viruses (four become endemic within populations, with the related serotypes), infections can spread rapidly ever-present risk of explosive epidemic throughout populations. This is compounded by outbreaks. the fact that dengue is transmitted by infected Aedes mosquitoes that breed in water containers Previous and recent outbreaks near or in domestic dwellings and rest indoors. In recent years, dramatic changes in urban and semiEpidemics of insect-borne diseases are often urban environments have not only led to increasing triggered by major demographic changes. For numbers of cases, but spread of the disease to new areas.
A
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Photo: Michelle Cornu
ANIMAL HOSTS such as deer, birds, poultry and other domestic animals are often a reservoir for arboviruses. Controlling a disease outbreak may require reducing the animal reservoirs.
Dengue is a major concern Dengue fever is now endemic in more than 100 countries in Africa, the Americas (including the Caribbean islands), the eastern Mediterranean, South-east Asia (e.g. Vietnam), China and the Western Pacific, with around 2500 million people now at risk from dengue. Current WHO estimates of 50 million cases of dengue worldwide every year, and the potential for explosive outbreaks make dengue a major international public health concern. All four closely related virus serotypes cause classical dengue fever as well as the more severe form of dengue hemorrhagic fever (DHF). This is a potentially lethal complication first recognized during epidemics in the Philippines and Thailand in the 1950s. Before 1970 only nine countries had experienced DHF epidemics, but this had increased to at least 36 countries by 1995. Today, DHF affects most Asian countries and has become a leading cause of morbidity and death among children in these regions. Vector control for population protection Vaccine development for dengue and DHF is complicated by the fact that any of the four serotypes of virus can cause the disease. Having dengue of one serotype provides immunity, but only against that serotype. The risk is then high for infection with another serotype and developing more severe symptoms. Thus any potential vaccine must provide immunity against all four serotypes to avoid more serious disease upon subsequent infection.
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This means the only method of control for dengue is at the vector level, i.e. combating Aedes mosquitoes. This also applies to other arboviral diseases, since there is no specific treatment for many of the diseases they cause. Vector control can involve treating the mainly man-made breeding containers with suitable larvicides (maintenance)* and in cases of outbreaks and epidemics reducing vector populations by space spraying (attack phase). Long-term strategies should involve a number of vector control strategies based on recommended WHO Integrated Vector Management (IVM, see page 12). Reducing animal reservoirs provide additional measures for controlling outbreaks such as Rift Valley fever (see case study in Saudi Arabia, page 24). Insecticide treated materials for bednets, curtains or covers for drinking water tanks are a means of protection for indoor environments (see Casa Segura, page 26). *WHO Guideline Specifications for Bacterial Larvicides for Public Health Use: http://whqlibdoc.who.int/hq/1999/WHO_ CDS_CPC_WHOPES_99.2.pdf
CONCLUSION Apart from vaccines against yellow fever, which still do not reach many populations, the most effective, and sometimes only method of preventing disease transmission by arthropodborne viruses is controlling the vector. Pro-active sustainable strategies to control vectors at various levels provide the best protection against infection over the long-term. Article on the enclosed Public Health CD-ROM 23
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Rift valley fever and dengue fever in Saudi Arabia
In Saudi Arabia, Rift valley fever and dengue fever represent the most serious virus-borne diseases transmitted by mosquitoes. This case study reports briefly on these two virus borne diseases, their epidemiological pattern, relation to mosquito vector species and current control measures.
Rift valley fever In the year 2000, an outbreak of Rift valley fever hit the southern parts of Saudi Arabia, mainly the Jazan and Aseer regions and Gunfudah Province. The death rate among animals was very high during the outbreak in the infected areas, and Rift valley virus was isolated from the blood of sheep and goats. A total of 885 human cases were recorded in Saudi Arabia during the outbreak period, the majority of those contracting the disease being men.
Photo: Goodshot/Corbis
Vector control operations
Entomological surveys in the area revealed the presence of the three major mosquito species: Anopheles, Aedes and Culex. Virus isolated from mosquitoes collected during the outbreak showed that the mosquito species Aedes aegyptii, which breed in water containers, was the major vector for Rift valley virus in the area. However, Culex mosquitoes were also found to be potential vectors for this disease. A mass program was rapidly designed and conducted to control disease transmission. Vector control operations were carried out by teams from the Ministry of Health, municipalities, the Ministry of Agriculture and other related governmental departments. The control program included the following measures: • Disposal of dead animals • Mass vaccination of animals • Residual house spraying using pyrethroid insecticides • Space spraying in highly infected areas using pyrethroids, ULV and thermal fogging • Aerial spraying of water pools and lakes formed by dams • Animal shelter spraying using organophosphorate insecticides • Spraying of mosquito larvae breeding sites • Distribution of impregnated bednets to individuals at high risk, especially those living in villages bordering Yemen
Provinces are in red.
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Dengue fever Dengue hemorrhagic fever transmitted by Aedes aegyptii (water-container breeding mosquito) is considered one of the major public health problems in western parts of Saudi Arabia. 1542 cases of dengue fever were reported in Saudi Arabia in 2006, of which 84.6% (1306) were found in Jeddah Province, 12.9% in Makkah and 2.26% in other regions. Similar climatic conditions and water storage systems are probably why Jeddah and Makkah represent the highest dengue endemic areas compared to other regions in Saudi Arabia. Particularly in the Jeddah Province, water storage containers create an ideal microclimate for the dengue fever virus vector to breed (see graph: Incidence of dengue fever in Jeddah Province).
INFECTION RATES reached their peak during the months from March to June, probably due to high humidity and pleasant weather, ideal breeding conditions for Aedes aegyptii mosquito.
Incidence of dengue fever in Jeddah Province (2006) Number of cases January
70
February
104
March
213
April
313
May
291
June
199
July
48
August
9
September
11
October
17
November
7
December
24
Mosquito survey results in the Jeddah Province revealed the presence of Anopheles, Culex and Aedes species. Aedes aegyptii larvae were frequently dominant in water containers found in human dwellings, ornamental plant market gardens, edges of swimming pools, water storage barrels and sinks located in buildings under construction. The author: SULEIMAN
Entomological surveys of MOHAMMED AL adult Aedes aegyptii SEGHAYER mosquitoes were carried out Supervisor of Parasitic Diseases Directorates. using CO2 activated traps Vector control placed on a weekly basis in Supervisor of Dengue randomly selected locations fever control committee, in the Jeddah Province. Adults Ministry of Health were also collected from Kingdom of Saudi Arabia human dwellings by aerosol spraying and using index white bed sheets. Larvae were collected from water pools and water storage containers, especially from houses under construction. Control of dengue fever was mainly carried out by municipalities in cooperation with the Ministry of Health Entomological Survey teams. Control measures included the following: • Treatment and quarantine of patients in infected areas • Health education carried out by Ministry of Health teams • Entomological surveys to determine breeding sites and adult density • Space spray (ULV and thermal fogging) of pyrethroid insecticides • Application of larvicides, e.g. organophosphates • Source reduction through elimination of mosquito larvae breeding sites and tight covering of water containers
Article on the enclosed Public Health CD-ROM
Total 1306
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Dengue
Casa Segura – a new approach for vector control Poor quality housing plays a vital role in dengue virus transmission. Long-lasting insecticide-treated materials used not only for bednets but also for curtains, wallhangings, etc., can protect people in homes, schools, or other buildings from exposure to the mosquito vector. This Casa Segura (safe house) approach may also provide protection against other pathogen vectors and pest insects, resulting in a broad spectrum strategy for disease and pest management.
E
pidemic dengue fever (DF) and dengue sion in the natural mosquito-human cycle. In hemorrhagic fever (DHF) have emerged as combination with targeted source reduction, Casa major public health problems in the Americas. Segura offers promise for preventing not only Current control measures used against the dengue dengue but also other vector-borne diseases transfever mosquito vector Aedes aegypti are often mitted indoors. reactive, following detection of dengue cases. This reactive approach has not proven to be The importance of housing quality in sufficient to stem the tide of dengue and new preventing vector-borne diseases proactive vector control strategies are desperately needed. The proactive Casa Segura approach Globally, the most important vector-borne diseases (VBDs) such as malaria, exploits long-lasting dengue, leishmaniasis or insecticide-treated materials Chagas, are diseases of to preclude the vector from poverty and social the epidemiologically inequality. Poverty is most significant point of directly linked to dramatic contact with humans: the growth in human home. Casa Segura can populations, unplanned prevent infected vectors urbanization, poor quality from transmitting the virus housing, lack of piped to humans. At the same water, etc., all of which The authors: time uninfected vectors influence VBDs. The are prevented from feeding BARRY BEATY developed world has been LARS EISEN on dengue virus-infected Arthropod-borne and Infectious Diseases fortunate to escape much humans in the indoor Laboratory, Department of Microbiology, of the incredible burden environment. Both these Immunology, and Pathology that pathogens transmitted strategies reduce the College of Veterinary Medicine and Biomedical by mosquitoes and their intensity of virus transmisSciences, Colorado State University, USA 26
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Photos: William Cotton
arthropod allies inflict on humans in developing countries. There are multiple reasons for this, but clearly one of the major determinants of unequal global burdens of VBDs is the quality of housing. This was illustrated in a recent entomological and epidemiological investigation of a dengue outbreak in the “sister” cities of Nuevo Laredo, Nuevo Leon, Mexico and Laredo, Texas, USA. In the US city of Laredo, there was very little dengue despite Aedes aegypti immature stages being relatively abundant in the domestic environment. Paradoxically, the Mexican city of Nuevo Laredo on the other side of the Rio Grande had lower abundances of Ae. aegypti immatures but greater numbers of dengue cases. The situation in the US city of Laredo can best be described as “Aedism without dengue”, similar to “Anophelism without malaria”. The investigators attributed this to several factors, among the most important being the quality of housing. More common use of window screens and air conditioning in Laredo likely prevented adult Ae. aegypti from entering homes and biting people. In Nuevo Laredo, female Ae. aegypti, although less numerous, could enter homes to transmit the virus or to become infected when feeding on infected humans, then amplifying PUBLIC HEALTH JOURNAL 19/2008
QUALITY OF HOUSING directly correlates with the prevalence of vector-borne diseases. Modern concrete housing (left) and Maya hut (right) in Yucatan, Mexico.
the virus during subsequent feeds. The viremia titer (concentration) is directly correlated with febrile illness and disease severity. Thus, when sick people are restricted to the home, they are the most infectious to vectors. Preventing vector contact with infected and infectious humans at the epidemiologic point of contact is a major opportunity for stopping dengue virus transmission. Current practices for dengue vector control In the Americas, dengue vector control programs include activities to control both adult and immature stages of Ae. aegypti. Outdoor ULV spraying during dengue outbreaks is ineffective in most situations due to the strong indoor association of female Ae. aegypti. Indeed, the female Ae. aegypti is an archetypical endophagic vector (feeds indoors), and depending upon the location and type of housing is also endophilic (rests indoors). If breeding sites are available inside the home, she may not even leave the house to lay her eggs. Targeted space spraying in and around the 27
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homes of diagnostically confirmed dengue cases is used for control of adult females. Although extremely laborious and expensive, large-scale indoor spraying can be an effective dengue outbreak intervention strategy. Control of the adult mosquito is frequently accompanied by environmental sanitation and source reduction to reduce populations of immature Ae. aegypti around and near homes. Chemical or biological larviciding and physical source reduction are widely used for controlling the immature mosquito stages and maintaining their populations below threshold levels, i.e. levels thought to interrupt dengue virus transmission. Source reduction/environmental sanitation measures were frequently associated with the “community-based approaches” of the 1980s and 1990s. However, this overall strategy was not as successful as hoped, and was often not well funded or supported in the long-term by government agencies. Indeed, source reduction may no longer be a practical sustainable control strategy due to the emergence of the “throw-away society” in even the poorest areas. New breeding sites, e.g. abandoned tires, bottles, cans and numerous other water holding containers, rapidly accumulate when environmental sanitation and source reduction campaigns end. The containers can and do become breeding sites for vector mosquitoes. The efficacy of larviciding may also be compromised by the emergence of insecticide resistance in Ae. aegypti populations against commonly used insecticides such as temephos (Abate). Control of dengue and other vector-borne diseases transmitted in the home Many globally important VBDs are primarily transmitted indoors, e.g. malaria in much of subSaharan Africa, dengue, leishmaniasis, Chagas and filariasis. Strategies aimed at preventing the vector from entering the home, or targeting the vector indoors, therefore offer great potential for reducing transmission of these VBDs. Indeed, the success of DDT in the past has been attributed to its ability to both kill and repel endophagic vectors from the home, thereby preventing indoor 28
transmission of vector-borne pathogens. In this regard, a major success story in VBD control in recent times has been the dramatic reduction of Chagas disease (American trypanomiasis) in South America following implementation of the Southern Cone Initiative (see page 19). This initiative included a combination of indoor residual spraying (IRS) to control reduviid vectors and screening of blood donors to prevent transfusion transmission. IRS dramatically reduced the prevalence of Triatoma infestans, an endophilic and endophagic vector, and dramatically reduced the incidence and prevalence of Chagas disease (see pages 16-21). The use of insecticide-treated bednets (ITNs) reduces the burden of malaria by preventing pathogen transmission in the home by night time feeding vectors. The advent of long-lasting insecticide-treated materials (LL-ITMs) in bednets, which can remain efficacious for more than 5 years, is a landmark event in vector control. Dengue virus transmission by Ae. aegypti, which is a day time feeder, also occurs most frequently in indoor environments. LL-ITMs offer great potential for prevention of dengue. The abundance of female mosquitoes indoors is likely a key basic determinant of risk for dengue outbreaks. Studies have been conducted to determine the potential of using ITMs as curtains to control Ae. aegypti in the home and to prevent dengue transmission. The studies used different insecticides and different materials as curtains, but each of the studies demonstrated that the basic approach can be remarkably efficacious. ITMs used as curtains dramatically reduced Ae. aegypti populations, and in some cases, was also shown to reduce dengue virus transmission in intervention versus control homes in Vietnam, the Philippines, Mexico and Venezuela. Entomological indices were not only dramatically reduced in and near RESEARCH AND CONTROL ACTIVITIES in Mérida, Yucatan. From top to bottom: Space spraying around premises. Surveillance for larvae in cemetery flower vases. Backpack aspiration for collection of adults inside the home.
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intervention homes, but there was also a community effect on vector abundance in neighboring untreated areas. This is potentially a major breakthrough for vector control because the curtains may be effective for many years. Casa Segura: a new proactive approach to control dengue The approach of using LL-ITMs for control of adult Ae. aegypti in indoor environments has been called Casa Segura (safe house). Casa Segura will prevent infected female Ae. aegypti from transmitting the virus and from becoming infected when feeding on viremic, dengue-infected persons. This will disrupt dengue virus transmission potential in two parts of the cycle. Casa Segura can be complemented with new methods and strategies for control of the immature mosquito stages. For example, containers differ dramatically in their productivity for Ae. aegypti. This means, the most effective use of control resources for immature insects may be to target especially productive container types. An integrated vector management strategy such as a combination of an LL-ITM based Casa Segura and container-targeted source reduction, could be implemented at low cost by the individual home-owner.
Photos: William Cotton
A Casa Segura safe house approach is currently being implemented for prevention of dengue through use of LL-ITMs (i.e., curtains covering windows and doorways) in Merida in the Yucatan peninsula of Mexico. This is being carried out in conjunction with implementing a national Patio Limpio source reduction program and in collaboration with:
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• Academic partners (Universidad Autonoma de Yucatan, Universidad Autonoma de Nuevo Leon). • Public health partners (Servicios de Salud de Yucatan, Mexico, Centro Nacional de Vigilancia Epidemiologica y Control de Enfermedades, Instituto Nacional de Salud Publica). • Industry partners (Bayer Environmental Science, Acytex Internacional).
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The Casa Segura implementation in Merida will assess the protective efficacy of LL-ITMs (deltamethrin) over a 3-year long-term study in a large city environment.
Monitoring for insecticide resistance and efficacy of insecticide-treated materials
Monitoring for, and management of insecticide resistance is a critical issue in control of VBDs The study will assess entomological outcomes such as malaria and dengue. The Casa Segura (e.g. abundance of adult Ae. aegypti in the home, approach for dengue control could potentially be pupal demographic surveys, larval indices, compromised by the emergence of insecticide presence and prevalence of insecticide resistance). resistance in local Ae. aegypti populations. The proposed studies will monitor It will also monitor epidemifor resistance to deltamethrin ological outcomes (e.g. in adults and temephos in seroconversion, dengue larvae in intervention and illness, virus isolation) in non-intervention sites. The intervention and non-interoperational studies will vention areas of Merida. permit monitoring for Potentially, LL-ITMs such as resistance (baseline measurecurtains, wall-hangings, etc., ments have already been can protect homes, schools, made) and importantly to or other structures where MONITORING FOR RESISTANCE to determine the epidemiopeople are exposed to deltamethrin in local Aedes aegypti populalogical significance of mosquito bites, for multiple tions is an important part of the studies. resistance. While it would years. The home and other (Photo: Centers for Disease Control and Prevention, seem that the proposed indoor environments may Dengue Branch, San Juan, Puerto Rico) approach would promote also be protected against other pathogen vectors as well as pest insects, resistance, vector populations may well be induced including nuisance Culex mosquitoes. Casa Segura to zoophily (animal hosts), thereby providing a may therefore provide a broad spectrum product refuge and mitigating development of insecticide for disease and pest management, rather than a resistance. targeted for a particular vector or disease. Conceptually, Casa Segura offers the protection of In addition, the long-term studies will provide the a western style home in terms of VBDs by opportunity to determine operationally if exploiting LL-ITMs (and potentially other inter- insecticide resistance does compromise the ventions in the future) instead of more expensive protective efficacy of Casa Segura. Potential screening, air-conditioning, etc. Some of the outcomes are that even in the presence of toxicopotential benefits of the approach are listed in the logical resistance, the excito-repellency effect of the insecticide still may preclude vectors from box below. entering the domicile. Alternatively, if resistance does result in vector ingress and endophagy, it will Potential benefits of the Casa Segura be critical to know the level of resistance in the vector control approach population that compromises the protective efficacy, and which will require shifting to new • Proactive vector control measure with insecticides. Operational village-scale trials in potential for preventing outbreaks of dengue Africa have demonstrated that resistance to and other vector-borne diseases pyrethroids (e.g. >85% prevalence of kdr* muta• Multi-year protection at low cost tion in mosquito populations) did not reduce the • Protects all inhabitants of a home protective efficacy of ITNs for malaria control. • Protects against multiple species of vectors The proposed studies will now determine the and diseases that are transmitted principally in the endophilic environment * knock down resistance • Potential for use of LL-ITMs as public health as well as a consumer product 30
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Photo: William Cotton
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MEASURING FOR LL-ITM curtains for a Casa Segura by Barry Beaty and Lars Eisen.
effect of pyrethroid resistance in Ae. aegypti on the efficacy of Casa Segura. The Casa Segura approach could also be compromised by the use of ITMs, originally developed for bednets, as curtains. The protective efficacy and duration of efficacy of ITMs used as curtains could be reduced by exposure to environmental conditions, especially UV light. The protective efficacy of the ITMs will be monitored in biological and kit assays for the 3 years of the study. Curtains that are no longer effective will be replaced. Insecticide resistance and protective efficacy of ITMs are critical issues with operational implications. In the field investigations in Merida, these factors will be monitored in the context of a dengue decision support system being developed by the Innovative Vector Control Consortium (IVCC) to enhance dengue vector control and program management. Monitoring of these issues can lead to policy changes for more efficient vector control. This includes switching to insecticides from different classes or with different modes of action in the event of emerging resistance; utilizing bi-treated materials to mitigate resistance; developing rotational replacement schedules for ITMs; exploiting new UV-protective insecticide formulations, etc. Importantly, the IVCC is partnering with industry to develop new active ingredients and formulations to provide critically needed new pesticides and tools to enhance the armory for and efficiency of vector control
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CONCLUSION The authors believe that the next 10 years will bring an explosion in low-cost, effective solutions, such as an LL-ITM based Casa Segura, for protecting homes and other indoor environments from vectors transmitting pathogens. This approach, when integrated into conventional control practices, offers great promise for control of VBDs. Future challenges include bringing the products to market and informing the end-user community that such products exist, are inexpensive and safe to use, will prevent disease and will improve the quality of life.
These studies were funded by the Innovative Vector Control Consortium as part of the Dengue Decision Support System project. The project was supported by teams at Colorado State University, Universidad Autonoma de Nuevo Leon, Universidad Autonoma de Yucatan, Servicios de Salud de Yucatan, and Servicios Estatales de Salud de Quintana Roo.
Article (with references) on the enclosed Public Health CD-ROM
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Leishmaniasis
An underestimated cause of suffering Transmitted by many sandfly species worldwide, Leishmania parasites cause diseases with different degrees of morbidity and mortality. Often programs to control malaria or dengue fever coincidentally reduce leishmaniasis. Few countries implement control for the leishmaniasis vector alone. Certain specific strategies could have profound effects on reducing vector reservoirs and infection rates in both humans and their canine companions. Recent developments include insecticide-impregnated collars and spot-on formulations for dogs.
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hlebotomine sandflies (order Diptera: family Fatal forms of the disease Psychodidae) are the proven or suspected vectors of leishmaniasis, a group of parasitic The more severe form of human leishmaniasis diseases present in at least 88 countries. The among the healthy (immunocompetent) population sandflies include over 40 Phlebotomus species in is zoonotic visceral leishmaniasis (ZVL) caused the Old World and a further 30 belonging to the by Leishmania infantum Nicolle in the Old World, genus Lutzomyia in the New World. They are also called Leishmania chagasi by Cunha and present in ecological settings ranging from very Chagas in Latin America. The second is anthrohumid tropical forest to deserts, from temperate ponotic visceral leishmaniasis (AVL), caused by cities situated at sea level to high mountain the parasite Leishmania donovani first described villages. Despite this diversity all sandfly species by Laveran and Mesnil. This is most prevalent in share a number of basic features. All are nocturnal, the Indian subcontinent regions of central Asia and resting during the day in dark, humid microhabitats Africa. Both forms are usually fatal in untreated or and able to insert themselves into confined spaces unresponsive patients. In some countries, sandflies to avoid extremes of temperature or humidity. also carry and transmit other pathogenic agents, They generally bite a variety of hosts and should such as Bartonella sp., phleboviruses and some be considered opportunistic flaviviruses, orbiviruses human-biters rather than and vesiculoviruses, anthropophilic. Their causing health problems flight ranges are limited to to humans and domestic a few hundred meters. Due animals (zoonoses). to their wide host range, small size and silent, nonDespite their small size hovering flight, people in and delicateness, female leishmania-endemic areas sandflies are hematophamay be unaware of their gous pests, so their control presence or role in the may be required even The authors: epidemiology of the where they are not active MICHELE MAROLI, disease, a fact that may as vectors. Sandfly GIANCARLO MAJORI compromise leishmaniasis breeding sites are Vector-Borne Diseases and International control efforts through generally difficult to find Health Unit, MIPI Department, Istituto Superiore di SanitĂ , Rome, Italy community participation. in nature, and therefore 32
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Photo: Michele Maroli
ONE OF MANY SPECIES of sandflies: Phlebotomus papatasi
control measures oriented specifically against immature stages are not feasible, although the effectiveness of a few biological and chemical agents has been demonstrated in laboratory studies. Theoretically, the vectors of leishmaniasis may be controlled using genetic or biological means, but at present, there are few effective methods other than chemical control. Control measures are aimed at reducing sandfly populations and human-vector contact by using: • Residual spraying in houses and animal shelters; • insecticide-treated nets for human use (ITNs); • repellents applied on the skin of people exposed to sandfly bites, and topical application of insecticides on dogs to prevent canine leishmaniasis (CanL). Residual spraying of houses and animal shelters Indoor residual spraying (IRS) has been successfully used in malaria control since the 1940s. IRS involves the application of long-acting insecticides on the walls and roofs of all houses and domestic animal shelters in a given area, in order to kill adult vectors that land and rest on these surfaces. The application of IRS is also an important method for controlling leishmaniasis. In the past, residual spraying against these diseases alone has only PUBLIC HEALTH JOURNAL 19/2008
been used in some areas. In most cases, insecticide treatment in human dwellings was intended to control mosquitoes or other insects, and the control of sandflies was coincidental. There are several examples of sandflies being affected by control
“
For many years, the public health impact of leishmaniasis has been grossly underestimated ... In fact, two million new cases are considered to occur annually, with an estimated 12 million people presently infected worldwide ...
”
(Source: www.who.int/leishmaniasis/burden/en/)
measures directed against other pest species. Malaria control in Italy based on the use of DDT, conducted in the late 40’s, significantly reduced transmission of Leishmania. The same occurred in India, Iran, Syria and Greece. In Kenya, pesticide use on cotton subsequently stored in human dwellings suppressed Phlebotomus martini as well as the malaria vector Anopheles gambiae. In Saudi Arabia, urban populations of Phlebotomus martini were reduced by ground and aerial application of diazinon against synanthropic flies such as Musca spp. Nowadays, only two countries from the Americas (Brazil and Paraguay) and three countries from the 33
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eastern Mediterranean region (Morocco, the Syrian Arab Republic and Islamic Republic of Iran) report insecticide use for leishmaniasis vector control, mainly for indoor residual spraying. Insecticides most extensively used for leishmaniasis vector control, by class of insecticide in the period 2003-2005, were: • Organophosphate: chlorpyrifos-methyl • Carbamate: propoxur • Pyrethroid: alpha-cypermethrin, cypermethrin, deltamethrin and lambda-cyhalothrin. Prerequisites for IRS implementation Residual spraying campaigns depend on the availability of a suitable public health infrastructure, including adequate supplies of insecticide, spraying equipment and trained personnel. Ideally, such personnel should be trained in insecticide application, monitoring techniques and interpretation of sampling data, as well as safety techniques. The effectiveness of residual spraying may depend on the degree to which sandflies have adapted to man-made environments, as well as the total area treated. Thus sandfly/leishmaniasis control by this method will be much more effective in urban situations, where every house and animal shelter is treated, than in rural areas. Here relatively few, widely dispersed dwellings are sprayed and the insects that bite humans and domestic animals represent a small proportion of the total vector population. In rural areas where large areas must be covered and suitable spraying equipment is available (including aircraft modified for crop-spraying) application of insecticides as aerosols may represent a viable alternative to residual treatment of houses or animal shelters. Use of insecticide-treated nets Insecticide-treated nets (ITNs) have proven efficacy in protecting humans against bites of mosquitoes, nuisance and arthropod vectors of malaria, lymphatic filariasis, Chagas disease and leishmaniasis. The use of untreated bednets shows only a low percentage of risk reduction in 34
developing these diseases. The synthetic pyrethroids used for treating the nets combine the properties of low to moderate mammalian toxicity, low volatility and high insecticidal activity. The feeding behavior of the arthropod vector is a key factor for the efficacy of ITNs, endophagic and endophilic vectors being the most affected by this control method. In fact, ITNs do not emit repellent vapor, but rather act as “baited traps” where sandflies attracted by exhaled CO2 and host odor die after landing on treated surfaces. The insects may either rest on impregnated nets for periods sufficient to absorb a lethal dose of insecticide, with significant induced mortality. Alternatively, fleeting contact with insecticide-treated surfaces are sufficient enough to cause excito-repellency (irritation and disorientation) resulting in reduction of blood-feeding. Most sustainable and cost-effective method The use of ITNs may represent the most sustainable method for reducing intradomiciliary transmission of Leishmania in many settings, especially in communities surrounded by forest, where the diurnal resting sites of vectors are unknown or inaccessible. ITNs are easy to use and require less technical and capital resources to implement, compared to other vector control methods. They are cost-effective, which has led to their extensive implementation by countries on a large scale. An advantage of ITN use as a vector control measure is that members of affected communities can treat the nets themselves, whether these are manufactured locally or supplied by health authorities. ITNs currently represent a key malaria control strategy, but low insecticide re-treatment rates remain a problem. To avoid the need for periodic re-treatment, it would be advantageous to have nets that retain insecticidal efficacy after many washes, practically for the life span of the net. The development of mosquito nets pre-treated with insecticide, long-lasting insecticidal nets (LLINs) is a solution to the difficulty of re-impregnating conventional nets. Two main methods are used for producing LLINs:
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• Incorporation of insecticide into fibers, and • surface treatment of net fibers or finished nets. Currently the two commercially produced bednets are Olyset® with 2% permethrin incorporated in polyethylene fibers, and PermaNet ® with deltamethrin (55 mg a.i./m2) coated on polyester. K-O TAB® 1-2-3 is a formulation of deltamethrin complimented with a binding agent for converting existing nets into LLINs. Laboratory and field experiments In laboratory bioassays, wild Perniciosus perniciosus and Phlebotomus papatasi confined in a cage were stimulated, using a bait, to walk across treated curtains (cotton, 0.5 cm mesh size) in order to test the effect of treatment on repellence, feeding rate and mortality. The results showed that permethrin (1 g/m2) had a low repellent effect on both sandfly species, but reduced feeding rates by 67% for P. perniciosus and 80% for P. papatasi. A study in Sudan, comparing the effect of treated bednets, untreated and no bednets, demonstrated that lambda-cyhalothrin (10 mg/m2) treated bednets provided complete protection against biting by Phlebotomus orientalis. Encouraging results on use of ITNs against phlebotomine sandflies have now been obtained from several countries, including Colombia, Venezuela, Kenya, Sudan and Syria.
NAMES OF LEISHMANIASIS The group of diseases that comes under the name leishmaniasis cause various symptoms and have acquired different names through history and throughout the world. Named after the Scottish pathologist Sir William Leishman who discovered the cause of kala-azar (one of the best known forms of the disease), leishmaniasis is also known as valley sickness, Andean sickness, Orient boils, Baghdad boils, black fever, Dum-dum fever and sandfly disease.
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In 1995, the use of bednets and curtains impregnated with deltamethrin at 26 mg a.i./m2 against Lutzomyia youngi was evaluated in Colombia. A significantly lower number of sandflies collected on human bait under treated nets than under untreated bednets was found. In addition, all sandflies exposed to treated mesh died within 24 h, so that the protective effect of the nets is supplemented to some extent by a reduction in sandfly population levels. Field experiments have also shown that ITNs not only reduce human landing rates of the sandfly Lutzomyia ovallesi, but also the abundance of this vector in Venezuela. 25% deltamethrin EC insecticide-treated bednets were also evaluated against the sandfly Lutzomyia longipalpis, the principal vector of ZVL in Latin America. Community-based trials The efficacy of ITNs against leishmaniasis has been demonstrated by a few community-based trials addressing Old World phlebotomine sandfly species, principally Phlebotomus sergenti Parrot, vector of Leishmania tropica in peridomestic/ urban foci in Syria, Iran and Afghanistan. In urban and rural settlements of Sanliurfa City, SE Anatolia, Turkey, large-scale field trials performed in an endemic focus of cutaneous leishmaniasis using K-O TAB (deltamethrin tablet formulation) showed high efficacy of impregnated bednets. This resulted in significant reductions in cutaneous leishmaniasis in the intervention areas, from 1.87% to 0.035% in Yenice and from 2.3% to 1.32% in Suru. Between May 1999 and March 2001, Médecins Sans Frontières distributed 357,000 insecticidetreated bednets to 155 affected villages to control visceral leishmaniasis (VL) in eastern Sudan. The protective effect, coverage (94% of individuals over 5 years old) and use of ITNs were evaluated and VL incidences were analyzed village by village from March 1996 to June 2002. Two years later, 44% of nets were reasonably intact. Regression analyses of incidence data from 114 villages demonstrated a significant reduction in VL per village and month following ITN use. 35
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The greatest effect was 17–20 months post-intervention, with VL cases reduced by 59%. This means an estimated 1060 VL cases were prevented between June 1999 and January 2001, a mean protective effect of 27%.
Preventative measures for dogs
Photo: Michele Maroli
Although certain wild animal species may be involved in the epidemiology of ZVL, domestic dogs seem to be the principal reservoir host of L. infantum throughout the world. Most efforts to A community-based intervention trial (KALANET), control ZVL currently focus on these animals, funded by the European Union, and aimed at particularly the search for a canine vaccine. While assessing the efficacy, acceptability and cost- waiting for a vaccine, preventing sandfly bites is a effectiveness of LLINs in preventing visceral priority to protect dogs from leishmaniasis as well leishmaniasis is ongoing in the L. donovani as to reduce the risk of human infections. Research has been carried out on endemic areas of the Bihar chemical compounds for use region along both sides of the on dogs as an effective Indian-Nepalese border. measure in controlling canine leishmaniasis (CanL) in Insect repellents endemic areas. In particular, the impact of mass use of The use of insect repellents or deltamethrin-impregnated protective clothing in areas dog collars on the incidence where Leishmania transof CanL has been evaluated. mission is extra-domiciliary Recently, a combination of may be the only prophylactic 10% imidacloprid and 50% measures available. They CUTANEOUS LESION due to permethrin has been should be considered by Leishmania tropica, Syria. developed in a spot-on dermal people only temporarily at risk of Leishmania infection, such as tourists, soldiers or topical formulation in order to provide treatment on maneuvers or hunters. Among the synthetic for, and prophylaxis against, ticks, fleas, chemical repellents, the gold standard is N, mosquitoes and phlebotomine sandflies. N-diethyl-3-methylbenzamide (DEET), which is not only highly effective against hematophagous Testing impregnated collars on dogs insects, but also well documented and in use for more than 50 years. Its efficacy has been proven It has been demonstrated that deltamethrin-impregagainst leishmaniasis vectors. During the last nated collars exert a potent anti-feeding effect on 10 years a new piperidine compound [1-piperidine- P. perniciosus and kill up to 60% of the insects carboxylic acid, 2-(2.hydroxyethyl)-1-methyl- within 2 hours of exposure. In Iran it was found propylester], known as KBR 3023, has been that dogs wearing collars were bitten by about developed and its efficacy was recently 80% fewer P. papatasi than unprotected animals. demonstrated against Phlebotomus duboscqui. The collars also have an anti-feeding and Laboratory tests on human volunteers, to compare insecticidal effect against L. longipalpis and the efficacy of NeemAzalÂŽ (34% Azadirachtin and L. migonei, new world vectors of ZVL and CanL 57.6% limonoids) and Neem oil, with that of the parasites. Based on laboratory results, it has been commercial formulation 20% KBR 3023 (Bayrepel, suggested that, at least in the Mediterranean and Bayer, Germany) against the bite of a well-known Middle East subregions, this measure could protect anthropophilic species, P. papatasi, showed 100% dogs from most sandfly bites and retain a protective and killing effect for a complete biting season. protection by KBR 3023 for 7 hours. Given their long-term effect (up to 34 weeks), it has been suggested that if the majority of dogs in a L. infantum focus had collars, this would reduce 36
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contact between vectors and vector reservoirs sufficiently to reduce the risk of infection for both dogs and humans. A village-based intervention trial carried out in the Campania region of Italy during two consecutive transmission periods has shown that collars confer up to 86% protection against L. infantum infection in pet dogs. A study performed in Iran indicated that use of impregnated dog collars significantly reduced ZVL incidence in both dogs and children. Spot-on formulations The repellent and insecticidal activity of a spot-on formulation (10% imidacloprid and 50% permethrin) against bites from P. papatasi, P. perniciosus and L. longipalpis has been demonstrated experimentally, leading to speculations that it could be effective in protecting dogs against CanL. The efficacy of this formulation was evaluated in an endemic area of southern Italy. The results clearly showed that the spot-on formulation is effective as a control measure in preventing CanL in the field. Other formulations, such as a solution containing 65% permethrin, have been shown to be effective against sandfly bites (P. perniciosus). Prevention of sandfly attack was also demonstrated for a permethrin/pyriproxyfen combination. Susceptibility of sandflies to insecticides DDT is the cheapest insecticide available, but for reasons of environmental impact and other concerns, its use is no longer permitted in most countries. It is also the only compound for which resistance has been recorded in sandflies. Fortunately, the insects remain susceptible to all the major insecticidal groups and there is no pressing need to develop new compounds specifically for sandfly control. To date, most records of resistance refer to one insecticide (DDT) in only three species (P. papatasi, P. argentipes and Sergentomyia shorti) in one country (India), although there are reports of increased tolerance of this compound from several countries. Sandflies have been shown to possess detoxification mechanisms that could confer
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protection against other insecticidal groups. Therefore, it cannot be ruled out that insecticide resistance may arise in other populations, either as a result of leishmaniasis control measures or by indirect exposure to compounds used to control malaria or dengue. CONCLUSION Although effective in urban areas with high concentrations of sandflies, IRS programs require suitable equipment and trained personnel. Also large-scale interventions based on IRS are often not sustainable in many situations. In rural areas where dwellings are more dispersed and surrounded by large, untargeted “reservoir� populations of sandflies, spraying of houses may be both impractical, for logistic reasons, and ineffective. ITNs offer the best solution in rural areas where transmission is largely intradomiciliary. Vector control is a particularly important tool since treatment of leishmaniasis is difficult, requiring trained doctors, and there is no vaccine available. The advantages of ITNs are that they can be used at the individual household level and provide collateral benefits such as privacy and control of other biting insects (mosquitoes, fleas, bedbugs). More focused measures are also required, including increased community participation and education in preventative measures against leishmaniasis. Inadequate control may merely increase the mean age of Leishmania infection, possibly increasing the severity of the disease. Improved information on aspects such as biting behavior and resting/ breeding sites would make delivery of existing compounds more efficient, resulting in lower intervention costs, higher efficacy and fewer detrimental effects on the environment. More www.who.int/leishmaniasis
Article on the enclosed Public Health CD-ROM
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Canine leishmaniasis
Protecting dogs against sandfly bites Canine leishmaniasis (CanL) caused by infection with the apicomplexa protozoan parasite Leishmania infantum is among the most important canine vector-borne diseases (CVBDs) in the Mediterranean region, South America and large parts of central Asia. Results of a study indicate highly effective protection of dogs by regular application of a spot-on combination containing synthetic pyrethroids.
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ogs remain the major reservoir reservoirs for the transmission of the The author: hosts for Leishmania infantum, NORBERT MENCKE pathogen. Currently, asymptomatic which causes visceral leishmaniasis in Bayer HealthCare AG, dogs from Leishmania infantumboth dogs and humans. The relevance Animal Health, Veterinary endemic areas are relocated by the Services, Monheim, of CanL has increased over the last thousands to central and northern Germany decade also in terms of its potential to European countries. The impact this may be transmitted via sandflies to humans. In endemic have on both dog and human health is currently not areas, children and adults suffering from immuno- fully understood. suppressive health conditions are particularly at risk. Two very different groups are observed in Preventing sandfly bites dogs: those with clinical signs of the disease (symptomatic) and others infected without any In the absence of any vaccine or a therapeutic clinical signs. Recent studies indicate that the treatment that fully eliminates the parasite from asymptomatic dogs are also capable of infecting dogs, prevention of sandfly bites is the priority to sandflies and thus must be included as important reduce the risk of canine leishmaniasis and DOG WITH CLINICAL SIGNS of canine leishmaniasis. Note the infected skin around the eyes and the nose. Skin with less hair is the preferred feeding site for sandflies and thus gets loaded with L. infantum.
Photos: Dr. Renate Edelhofer, Institute of Parasitology and Zoology at the University of Veterinary Medicine, Vienna, Austria
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Deltamethrin is marketed as a treatment for collars, while permethrin is formulated as a highly concentrated dermal spot-on application. The latest release is a combination containing imidacloprid and permethrin, marketed throughout Europe under the trade name Advantix速. The repellent and insecticidal efficacy of this 10% imidacloprid plus 50% permethrin spot-on combination (Advantix速) against sandflies (Phlebotomus papatasi, P. perniciosus and Lutzomyia longipalpis) has been reported from three laboratory studies. In these studies, the imidacloprid/permethrin combination was effective for up to 3 weeks against the most important sandfly species (P. perniciosus) of the Mediterranean region that transmits L. infantum. Testing the repellent effect With the distinct repellent effect, it was postulated that the combination might be effective in protecting dogs against CanL. Thus a study was conducted to investigate the repellent effect of the combination under natural conditions in a high endemic sandfly area in Southern Italy. The aim of the study was to evaluate the efficacy of the combination under field conditions, specifically its capability to prevent CanL in dogs kept in kennels. In February, prior to the sandfly season, 845 dogs from two kennels (KB and KG) in Apulia were initially tested for CanL by serology (IFAT), cytology (parasitological examination) and PCR. Of the initially tested 845 dogs, 631 negatively tested dogs were allocated to one of three groups: Group A was treated with imidacloprid/permethrin once a month; Group B was treated every two weeks; and Group C was left untreated as a control group. L. infantum infection was examined prior to, and at the end of the sandfly season in
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Photo: Asia Images
subsequently reduce the risk for humans. Animal health products containing insecticides that effectively repel sandflies are limited to the chemical class of synthetic pyrethroids. From this class only two compounds, deltamethrin and permethrin have been investigated and gained marketing approval within the EU.
INFECTED DOG showing the typical canine leishmaniasis malformation of the claws.
November 2005, and again before the following sandfly season in March 2006. The prevalence of seropositive dogs kept together with the other dogs included in the study was 22% (Group A), 16.5% (Group B) and 18.5% (Group C) in the KB kennel and 24% (A), 28.5% (B) and 20.3% (C) in kennel KG. The incidence recorded for the dogs in the untreated control group was 9.8 and 10.5%. Dogs treated with both application regimes displayed a very high percentage of protection from sandfly bites. The efficacy recorded for dogs treated once a month (Group A) was between 88.9% (kennel KB) and 90.36% (kennel KG), and treated twice a month (Group B), between 90.73% (kennel KG) and 100% (kennel KB).
CONCLUSION The results of the study clearly indicate that due to its repellent activity against sandflies, the imidacloprid/permethrin spot-on combination is highly effective in preventing dogs from being infected by L. infantum under natural conditions in endemic areas.
Article (with references) on the enclosed Public Health CD-ROM
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Increasing role of foundations working against global inequity
Catalysts for global health efforts A new era of philanthropy started over ten years ago when Bill Gates decided to give away some of his fortune to reduce health inequalities between rich and poor around the world. Now joined by other entrepreneurs, politicians and celebrities, creating foundations and giving donations to help improve public health is making the headlines.
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riginally founded in 1994 shortly after their marriage, the global icon of the personal computer and his wife renamed their charity the “Bill & Melinda Gates Foundation” in 2000. By far the largest charitable foundation in the world was launched by US$ 26 billion endowed by Bill and Melinda Gates. Bill & Melinda Gates Foundation The foundation, headquartered in Seattle, Washington, and run by CEO Patty Stonesifer, mainly works through partnerships (NGOs, organizations). It awards grants to fund a wide range of projects, research and other efforts in diverse areas of global development, with the priority being global health.
Photo courtesy of the Bill & Melinda Gates Foundation / Liz Gilbert
The Gates Foundation’s Global Health Program aims to increase access to life-saving vaccines, drugs and other tools, and support research to
A YOUNG BOY receives a vaccine and an examination for Trachoma from a traveling doctor, Kenya, 2001.
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develop new health solutions that are affordable and effective. Specific targets include HIV/AIDS, malaria, tuberculosis, malnutrition, acute diarrhea and respiratory infections, tropical parasitic diseases, and reproductive, maternal and child health. By the end of 2006 the foundation had awarded almost US$ 7.8 billion in grants for health-related projects. For example, to the Global Alliance for Vaccines and Immunization (GAVI), to the Global Fund to Fight AIDS, Tuberculosis, and Malaria, to the Africa Malaria Network Trust (AMANET), to the Clinton HIV/AIDS Initiative (see below) and to the WHO to support the RBM Partnership. “In the area of malaria control, the size of the foundation’s grants has enabled it to energize research and forge partnerships among academia, governments, and industry much more effectively than other institutions have,” said Brian Greenwood, a professor at the London School of Hygiene and Tropical Medicine. Pursuing similar goals Bill and Melinda Gates are joined by other entrepreneurs, politicians and celebrities. Warren Buffett, the world’s second richest businessman set up plans to donate most of his personal fortune to the Bill & Melinda Gates Foundation. Buffett’s gift of around US$ 31 billion will double the foundation’s endowment to approximately US$ 60 billion. He decided to entrust his donation to his friend Bill Gates, since there seemed little point in starting afresh to pursue the same goals.
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Bill and Melinda Gates in Seattle
Call for eradication of malaria At the Malaria Forum in Seattle, October 16-18, 2007, Bill and Melinda Gates addressed malaria scientists, global health leaders and policymakers from around the world urging them to embrace “an audacious goal — to reach a day when no human being has malaria, and no mosquito on earth is carrying it.” After peaking at nearly three and a half million deaths in the 1930s, global efforts managed to reduce this to half a million at the end of the 1960s. But malaria eradication campaigns collapsed due to declining donor funding and growing resistance to drugs and insecticides. Malaria programs since then have focused on reducing, not ending, the burden of malaria. Therefore, the disease has crept back to five hundred million cases every year, killing more than one million people, mostly African children. “Advances in science and medicine, promising research, and the rising concern of people around the world represent an historic opportunity not just to treat malaria or to control it – but to chart a long-term course to eradicate it,” said Melinda Gates. Melinda Gates listed three reasons why eradication must be the goal and not simply
The William J. Clinton Foundation was set up by the ex-president to create a forum linking projects with people and organizations who can fund them. In 2005, Bill Clinton launched the Clinton Global Initiative. At the second annual meeting in 2006, over 1,000 world leaders made 262 commitments, amounting to more than US$ 7.3 billion, which will go to some 500 organizations helping people in more than 100 countries. The Carter Center founded in 1982 by the former US president is “committed to advancing human rights and alleviating unnecessary human
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reducing or controlling malaria. The first is ethical – the human cost; the second financial – the never-ending costs of control; and the third is epidemiological – the repeated ability of vector and parasite to develop resistance to insecticides and medicines over time. “We have a real chance to build the partnerships, generate the political will, and develop the scientific breakthroughs we need to end this disease,” said Bill Gates. “We will not stop working until malaria is eradicated.” He added that new initiatives such as the Global Fund, the World Bank’s Malaria Booster Program and the US President’s Malaria Initiative, “are bringing new energy and resources to the global effort to control malaria.” Also released at the forum, a new UNICEF report documented the impressive progress of recent malaria control efforts. For example, annual supplies of insecticide-treated bednets to prevent malaria more than doubled in recent years, from 30 million nets in 2004 to 63 million nets in 2006. Source Bill & Melinda Gates Foundation: www.gatesfoundation.org
suffering”. In the area of health, it focuses on more neglected, but debilitating diseases (neglected tropical diseases, see page 14) such as Guinea worm and river blindness, both caused by parasites. Also started up by a philanthropist donation of US$ 1 billion from Ted Turner in 1998, the UN Foundation “builds and implements publicprivate partnerships to address the world’s most pressing problems, and broadens support for the UN through advocacy and public outreach.” The UN Foundation is a public charity, and has been 41
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IVCC and Bayer Environmental Science
Valuable contract The Innovative Vector Control Consortium (IVCC) was formed with a US$ 50.7 million grant from the Bill and Melinda Gates Foundation and comprises leading research institutions in the field of developing vector control products and information systems. IVCC’s strategy “to identify opportunities for the development of new products, strategies and tools for improved vector control and to enable and support those projects through developing partnerships that will provide the resources to bring them to fruition” is highly relevant to industry partners such as Bayer Environmental Science. Signing of an agreement between Bayer CropScience and IVCC in September 2007 to collaborate on two projects aimed at fighting malaria confirm the commitment of Bayer to these strategies. Together with the Medical Research Council of South Africa, the Liverpool School of Tropical Medicine (LSTM) and the London School of Hygiene and Tropical Medicine, the first project aims to discover a long-lasting solution for Indoor Residual Spraying to control mosquitoes. The second project in collaboration with the LSTM and the University of Liverpool is focusing on the problem of mosquitoes developing resistance to vector control products, which makes efforts to combat the transmission of malaria and other diseases more and more difficult. working with the UN for many years to combat malaria. It recently launched a scheme for anyone to contribute to buying a bednet for just US$ 10, including distribution and instruction in its use. “Nothing But Nets” has already gained the support of diverse organizations and individuals in their campaign to help protect children from malaria. At the United Nations in March 2006, the Roll Back Malaria Partnership Special Envoy and UNICEF Goodwill Ambassador Youssou N’Dour, announced a new African health initiative to prevent malaria. N’Dour not only reaches audiences all over the world with his music, but also his commitment to speaking out about social issues, children’s right to survival and fighting malaria in Africa (see also Public Health Journal No. 17). Film stars Angelina Jolie and Brad Pitt recently set up their own charity, the Jolie-Pitt Foundation, and will donate US$ 1 million each to Global Action for Children and Doctors Without Borders.
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Many other celebrities in music and sports contribute to charitable organizations and participate in fund-raising events. Sporting associations also support specific charities, such as the world football’s governing body, FIFA, which chose SOS Children as the official 2006 World Cup charity. CONCLUSION Perhaps almost as important as the money they donate is the example set by various foundations and celebrities. They create a focus and pave the way for other commitments, such as the US Presidential Malaria Initiative (PMI). By drawing attention to global problems, they attract publicity, funding and action from others to become involved in fighting poverty, disease and other inequalities throughout the world. Article and links to the foundation websites on the enclosed Public Health CD-ROM PUBLIC HEALTH JOURNAL 19/2008
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New private-public initiatives
Generating complementary actions Total non-governmental aid to the developing world from private and voluntary organizations far exceeds the amounts of official developmental assistance from industrial countries. But now the public sector in North America and Europe is mobilizing with a number of initiatives to interact with private funding and generate complementary and efficient actions.
O
fficial aid for all programs in the US, for example, almost doubled the sum of US$ 9.9 billion in 2000 to reach US$ 19.7 billion in 2004. But in the same year private contributions to global aid organizations amounted to more than US$ 79 billion in the US. UNITAID, Global Business Coalition (GBC), Global Health Initiative (GHI), CAMA, and others, have focused on establishing private-public initiatives to combat the major health problems facing developing countries. France taking a lead In July 2005, President Jacques Chirac of France sent a letter to 145 world leaders asking them to support his proposal for generating funds to help the global fight against HIV/AIDS, tuberculosis and malaria. He first discussed the idea at the World Economic Forum held in Davos, Switzerland at the beginning of 2005. He stressed that these diseases primarily arise in developing countries, mostly Africa, and the problem is not simply a health matter but a political one. His proposed initiative was to set up an International Drug Purchase Facility called UNITAID, with the mission to “offer long-term access to high-quality treatment at the lowest price for those in most urgent need.”
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UNITAID Born from the desire to create additional, huge amounts of sustainable funding independent from any government, Chirac’s idea was to create a solidarity surcharge on every airline ticket bought in a participating country – a kind of global initiative by ordinary people. UNITAID was officially inaugurated at the UN general assembly in New York on September 19, 2006. With the support of former UN General Secretary Kofi Annan, Brazil, Chile, Norway and the UK, followed by Belgium, Luxemburg and Spain, joined with France. Their goal was to create UNITAID as an international initiative for generating sustainable, long-term financing to buy medications for the three deadly diseases. Earlier in 2006, a partnership with FIFA – symbolically signed on a football – also ensured UNITAID was promoted throughout the World Cup.
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reach US$ 500 million in 2009. This money will be used to fund public health programs that complement those of other organizations and foundations. For example, partnerships could be formed with the Global Fund to fight AIDS, Tuberculosis and Malaria, WHO, UNICEF, Bill & Melinda Gates Foundation and Clinton Foundation (see page 40).
Photo: Bayer
Global Health Initiative
AS A MEMBER of the Global Buisness Coalition (GBC) Bayer is focusing on insecticide-treated bednets.
Partners from North and South Including the founding members, 23 countries are now setting up schemes for a surcharge on airline tickets to create budgets that are already funding, or will fund UNITAID (e.g. Cambodia, Cyprus, South Korea, Gabon, Jordan, Mauritius, Mali, Nicaragua). At the 24th Africa-France summit in Cannes on February 16, 2007, 18 African countries signed political and legal agreements to join UNITAID (South Africa, Benin, Burkina Faso, Cameroon, the Congo, Ivory Coast, Gabon, Liberia, Madagascar, Mali, Morocco, Namibia, Niger, Central Republic of Africa, Senegal, Sao Tomé and principality of Togo). They are also intending to set up similar solidarity contributions on air tickets towards funding UNITAID. As these lists show, a particular feature of UNITAID is that not just Northern countries are donating aid but also Southern ones are joining in as partners. It is estimated that UNITAID’s budget was more than US$ 300 million in 2007 and will probably 44
The World Economic Forum set up the Global Health Initiative (GHI) as a unique private-public partnership addressing the problems of HIV/AIDS, tuberculosis and malaria and bringing information to millions of people. About 4 million people are reached through the Indian Business Alliance to Stop TB. The China Health Alliance (CHA) will reach up to 5 million, particularly migrant workers at risk from infection by HIV/AIDS or tuberculosis. Global Business Coalition Founded in 2001, with offices in New York, Beijing, Geneva, Johannesburg, Nairobi and Paris, Global Business Coalition (GBC) believes that whatever their expertise and global location, the business sector can offer much more than financial support to combat HIV/AIDS, TB, and malaria epidemics. By developing a rapidly expanding alliance of more than 220 international companies, GBC’s aim is to link global business with the public health community and mobilize the business sector’s skills and expertise. To optimize these resources, the Global Business Coalition has created a broad network of partnerships with leading international NGOs, public health organizations and international agencies, including the Global Fund, Roll Back Malaria Partnership (RBM), the President’s Malaria Initiative (PMI) and Nothing But Nets. Some of the international companies involved in GBC are Bayer AG, Becton, Dickinson and Company, BHP Billiton, BP, Deutsche Post World Net, GlaxoSmithKline, JN-International Medical Corporation, Lafarge, Novartis, Pfizer, Royal
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Dutch Shell, Sumitomo Chemical, Vestergaard Frandsen and Virgin Unite. Bayer has been a member of this initiative since March 2003, promoting the distribution of insecticide-treated bednets that provide protection against malaria. The company also supplies these nets and the insecticide impregnation kits to organizations such as the Red Cross, the WHO, UNICEF, USAID, PSI (Public Health No. 18) and the Global Fund to Fight AIDS, Tuberculosis and Malaria. Recently, Bayer was approached to join to a public-private partnership project with the Innovative Vector Control Consortium (IVCC) to develop new vector control solutions against malaria. Corporate Alliance in Africa Although there are business coalitions addressing various health issues in Africa on a small scale, the Corporate Alliance on Malaria in Africa (CAMA) is the first coalition of businesses dedicated to combating malaria in Africa. Malaria prevention and treatment can consume up to 25% of an average African family’s net income, accounting
CAMA Vision: To reduce the incidence of malaria by promoting the private sector cooperation on malaria control projects in Sub-Saharan Africa. Mission: To provide a forum for corporations, working with governments and NGOs, to cooperate on existing malaria intervention projects in Sub-Saharan Africa, encourage the creation of new partnerships, share best practices and promote understanding of the fight against malaria. Goal: To maximize malaria intervention benefits through the optimization of in-country cooperation, information sharing and private sector advocacy.
for 1.3% of the annual gross domestic product (GDP) of affected countries. In other words, malaria costs Africa about US$12 billion in economic losses each year. In response to the President’s Malaria Initiative for Africa it was decided that companies with interests and health projects in Africa would join forces to promote private sector cooperation in malaria control and prevention. Companies who have already committed to the goals and objectives of CAMA are Cameron International, CCC, Chevron, Coca Cola Africa, EDG Engineers, Global Industries, Haliburton, Hess, Marathon Oil Company, Noble Energy and WorleyParsons. Among these Coca Cola is the largest private sector employer in Africa with 60,000 employees in all 56 countries. Vector control input CAMA is also working together with the Global Business Coalition. As a member of GBC, this means Bayer AG is the only company in CAMA involved directly in researching, developing and implementing methods to combat malaria. Bayer Environmental Science has many years of experience in disease transmission prevention and mosquito vector control. This expertise will be put to use in the CAMA/GBC workplan scheduled to start in 2008. CONCLUSION There are a growing number of initiatives promoting interactions between the public sector and groups in the private sector, NGOs, foundations and organizations. This can bring in private funding to coordinate with public programs in a broad campaign to dramatically reduce deaths due to HIV/AIDS, tuberculosis and malaria worldwide.
Article on the enclosed Public Health CD-ROM
Websites of the initiatives: see link list on page 61
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NGO
CORE Group: Network of NGOs
Coordinating efforts to improve children’s health
T
wo thirds of the children worldwide who never reach their fifth birthday die due to a disease such as malaria, measles or pneumonia, or simply malnutrition. This means almost six and a half million young children die each year from preventable or treatable diseases or inadequate living standards such as extreme poverty. CORE Group provides a network resource for international non-governmental organizations (NGOs) and private voluntary organizations (PVOs). These organizations can then work together with local partners and governments, providing advice, working out strategies and coordinating programs to help the mothers and children most at risk. Working together Indeed, the essence of CORE Group’s approach is coordination and cooperation. Their mission is to optimize and focus the efforts of different * The CORE Group was originally founded as “Child Survival Collaborations and Resources” Group.
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Photo: Nigel Marsh / World Vision
The CORE Group* is a global leader in organizing efforts to deal with major health issues for children. Group members include a range of NGOs dedicated to combating diseases, malnutrition and other factors to increase children’s survival and well-being. They have been working all over the world since 1997. The following article highlights some of CORE Group’s activities.
organizations, as well as to provide links with universities, Ministries of Health and local governments, the private sector and charitable donors. To streamline their efforts, CORE Group has created eight working groups, each concentrating on a specific critical topic. These include problems such as malnourished children, malaria treatment for children in Africa, HIV/AIDS, reproductive health, tuberculosis, and training in child health program management. By joining a specific working group, different organizations and NGOs can combine forces to carry out studies, provide information, coordinate strategic
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NGO
CORE Group has 47 member organizations working in more than 180 countries. They have a combined annual revenue of approximately US$ 9 billion (November 2006). One of CORE Group’s priorities is the Malaria Working Group.
A further aim of CORE Group members is reaching the Millennium Development Goals, which are to reduce child mortality by two-thirds and maternal mortality by three-quarters by 2015. Malaria Working Group One of CORE Group’s priorities is the Malaria Working Group, which is particularly active in Africa. As the elected NGO representative for the Roll Back Malaria (RBM) partnership until September 2005, CORE Group helped establish the RBM East Africa, West Africa and Central Africa Regional Networks. Local activities involved setting up national NGOs in Kenya, Tanzania, Uganda and Zambia in 2003 and 2004.
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The Malaria Working Group supports existing national collaborative partnerships and promotes new partnerships in which NGOs can actively be engaged to scale up malaria prevention and control.
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alliances and help implement local programs, rather than working on their own and repeating each others efforts. In February 2005, the CORE Group received an award from the US Agency for International Development (USAID) Child Survival and Health Grants Program to run the Child Survival and Health (CSH) Network Program for five years. This program involves coordinating private voluntary organizations, NGOs and local partners to improve health programs for infants, children and mothers in a number of areas, including combating infectious diseases.
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They then helped these NGOs to organize workshops such as National Fresh Air Malaria Workshops in Ghana, Tanzania, Uganda and Sierra Leone, and to find funds for community-based actions. An important activity is carrying out surveys and studies in the field, which involves traveling to different districts to talk directly to the people, and to provide them with information about malaria. CORE Group therefore helps coordinate national NGO programs for malaria prevention and control by supporting community-based actions. There are, for example, workshops for learning about insecticide-treated bednets and local open-air theatre encouraging parents to take their sick children to local clinics rather than local healers. 47
NGO
MEMBERS ADRA, Africare, Aga Khan Foundation, AMREF, American Red Cross, CARE, Catholic Relief Services, Christian Children’s Fund, Christian Reformed World Relief Committee, Concern Worldwide, Counterpart International, Curamericas Global, Doctors of the World, FOCAS, Food For The Hungry, Freedom from Hunger, Future Generations, Global Health Action, Haitian Health Foundation, Health Alliance International, Helen Keller International, Hesperian Foundation, Hope Worldwide, InterChurch Medical Assistance, International Aid, International Eye Foundation, International Medical Corps, International Relief and Development, International Rescue Committee, La Leche League International, MAP International, Medical Teams International, MCDI, Mercy Corps, Minnesota International Health Volunteers, Partners for Development, PATH, Plan USA, Population Services International, Project Concern International, Project HOPE, Salvation Army World Service Office, Save the Children, White Ribbon Alliance, World Neighbors, World Relief, World Vision.
Shrouds and coffins Many superstitions, such as bad spirits, are still associated with the disease malaria. As an example, sleeping under a bednet is often associated with shrouds and coffins, in other words bad luck. It is essential to overcome the local people’s doubts, and in particular to talk to local healers to gain their understanding and support. For example, the Kenya NGO Alliance Against Malaria (KeNAAM), founded with CORE Group’s support in May 2003, is involved in such local activities. KeNAAM also serves as a representative for NGOs on the Global Fund CCM, and is a partner in the VOICES for Malaria Advocacy project, advocating for the elimination of malaria through sustained partnerships in Kenya. 48
CORE Group also helped the Tanzania NGO Alliance Against Malaria (TaNAAM) to find funds for distributing insecticide-treated bednets, training local health workers and educating local communities about malaria prevention, control and treatment. TaNAAM also organized discount voucher schemes to help mothers purchase insecticide-treated bednets as well as encouraging them to use these nets. However, implementing best practices and especially new innovations in the field of malaria prevention and control are only possible through contacts and partnerships with international organizations. Public and Private Sector Partnerships CORE Group works together with the Measles/ Malaria Partnership to help set up partnerships between national NGOs and other CORE Group members, the WHO, UNICEF and private organizations. In 2004, Bayer Environmental Science collaborated with CORE Group to support five Fresh Air Malaria Workshops. At a CORE Group meeting Bayer Environmental Science participated in an event promoting long-lasting insecticidetreated mosquito nets. CONCLUSION The CORE Group is an association of organizations that work together to coordinate and cooperate with international NGOs, academia, national governments, the private sector and donors. CORE members help support national NGOs and governments to plan, organize and run local projects. These activities significantly improve health care through learning, monitoring, training and development programs to improve the health and well-being of mothers, children and communities in developing countries worldwide. More www.coregroup.org
Article on the enclosed Public Health CD-ROM
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Photo: Elisabeth Friedrich
NGO
TO DATE, MCDI has provided technical assistance in over 40 countries in Africa, the Caribbean, Central and South America, and the Middle East.
NGO Profile: MCDI
Developing health infrastructures Medical Care Development International (MCDI) is actively involved in a number of issues in developing countries. These range from child survival and disease management, reforming the health sector, education and rural development, water supply and sanitation, HIV/AIDS, and combatting malaria.
S
et up in 1977, MCDI was based on the national success of Medical Care Development (MCD), which was established in 1966 to provide health services in remote areas of the USA. As an international division MCDI was created to extend Medical Care Development’s mission “to meet the needs of disadvantaged and vulnerable population groups in developing countries”. MCDI, a CORE Group member, is supported by organizations such as the World Bank, the United States Agency for International Development (USAID), the United States Department of Health and Human Services, the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), as well as many private companies. Medical Care Development Inc. has its headquarters in Augusta, Maine, USA. The international
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division now coordinates eight main projects worldwide. These include child survival, health sector reform, architecture and engineering, education and rural development, water supply and sanitation, HIV/AIDS, malaria treatment and control, as well as orthopedic and rehabilitation services. MCDI staff comprise a range of experts from the health sector, from physicians to equipment specialists, as well as representatives from the US, Portugal, Madagascar, India, France, Sierra Leone and Brazil. Child survival An important activity of MCDI is the various projects worldwide directed at improving the health, well-being and survival of children in developing countries. For example, in Benin, MCDI is involved in a Food for Education and Child Nutrition (FFE) program. In the northern 49
NGO
rural areas of Atacora/Donga the aim is to improve primary school attendance by supplying breakfast and lunch (plus extra rations for girls). They also help improve schooling by training teachers and supplying school materials, as well as educating school children and other community members about health and nutrition, including de-worming. The World Health Organization (WHO) supplies medications for the de-worming treatment intended to reach 12,500 primary school children in 61 schools over the 2-year project period.
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We will seek to empower families with the knowledge and behavior needed to improve infant and child survival and maternal health and care. We will develop and disseminate tools, mechanisms and strategies that improve access and management of sustainable levels of health care services.
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Specifically for the Borgou district in Benin, MCDI received funding from USAID in 2003 to set up Integrated Management of Childhood Illness (IMCI) activities. The main aim is to improve the health of women of child-bearing age in the Tchaoutou and N’Dali areas. They are particularly focusing on pneumonia, diarrhea related diseases, vaccination, breastfeeding and nutrition, HIV/ AIDS and malaria. In Mozambique, MCDI pursues integrated management of childhood illnesses combined with safe motherhood, health system support, disease surveillance and improving the local Health Department’s ability to deal with epidemics. One specific project is their involvement in restoring the community center in the city of Cuamba. This city suffered particular hardships during and after the Mozambique civil war as the surrounding countryside became a guerilla warfare area for government and rebel troops. Not only was the city often cut off from external contacts, including food supplies, but most of the young men were called upon to fight. Today, about 40% of the 50
estimated population (80,000) are younger than twenty. By providing facilities for outdoor and indoor sports, theatre, workshops, AIDS counseling and numerous other community activities, the center should help encourage these young people to live healthy lives. Malaria control MCDI also organizes and runs the Bioko Island Malaria Control Project in Equatorial Guinea, funded by Marathon Oil Company and its partners (see Public Health Journal, issue 18, page 38). Malaria has long been a major problem in Equatorial Guinea, especially for children and pregnant women. Of the estimated population of 462,000, about 30% are children under 5 years of age, who are the primary sufferers of this disease. Previous attempts to control malaria were unsuccessful, mainly due to the lack of resources and funding needed for diagnosing and treating the disease, for implementing adequate vector control and for proper monitoring of progress. The MCDI employs three main intervention strategies in the Malaria Control Project: vector control, case management, surveillance and evaluation. The latter also involves cooperation with the Medical Research Council of South Africa, Harvard School of Public Health and others. Also important are up-to-date laboratory analyses, e.g. a technique developed by Yale University will be used to determine the actual incidence of malaria in patients with fevers attending health centers. This is important for assessing both baseline and achieved target levels. It is also needed for cost effective case management and determining the current extent of drug resistance, for example resistance to Artemisinin combination therapies. A baseline survey collected information on positive malaria parasite tests in children aged 2-14, mortality of children under 5, use of bednets, knowledge of mothers in recognizing signs of illness and how and if they made use of local health services. In addition, as a follow-up to indoor residual spraying with deltamethrin,
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NGO
MCDI projects in Africa* Tunisia HMIS Study EMS Study
Senegal Water & Sanitation Guinea-Bissau Hospital Rehabilitation
Chad Child Survival
Equatorial Guinea Malaria Control Project Sudan Rumbek Rehabilitation Project
The Gambia Health Sector Requirements Study
Djibouti Water & Sanitation
Guinea HSPS Sierra Leone ADB Study Ghana Water & Sanitation
Tanzania PJD / ADB Health Study PJD / WB Health Sector Reform
Benin Togo HEPS HS Support to Child Survival CS Projects FFE Program
Zanzibar Health Development Requirements Study
Mali Northern Region Health & Hygiene Project
Madagascar Betioky Child Survival Sante II SanteNet AEPA PJD / Family Planning
Angola World Bank Health Sector Reform
South Africa Ndwedwe Chils Survival Ndwedwe Initiative HIV/AIDS/TB Traditional Healers Youth HIV VCT (JHU) HIV/AIDS Activities (REACH) Zinc & Vitamin A Supplementation Project Cape Verde (not pictured) Personnel Training and Development of Health Infrastructure Projects Completed
Lesotho Health Sector Study Gov’t / CHAL Partnership Study HR Development Study PJD / Water Sector Reform PJD-HIV/AIDS
Current Projects
www.mcdi.mcd.org
Article on the enclosed Public Health CD-ROM PUBLIC HEALTH JOURNAL 19/2007 19/2008
Swaziland Prevention of HIV/AIDS in USDF
* Status as of April 2007
Project Development
mosquitoes are collected in window traps to provide data on vector density and the proportion of mosquitoes infected with the Plasmodium parasite. All these data are important for improving vector control strategies, management of actual cases of the disease and how to better prevent and control malaria in this region. More
Mozambique Niassa HSDS / JSL / MSH PJD / Community Based STD / HIV/AIDS Project
CONCLUSION MCDI provides technological, scientific, management and organizational tools, mechanisms and strategies to improve access to sustainable levels of health care by communities most needing this. By working together with organizations ranging from international multi-lateral institutions down to community groups they seek to help families find ways to improve the quality of affordable care needed to improve infant and maternal health.
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NGO
Health care reaching Amazonian Indians
Mosquito nets for the Yanomami For three to five months every year, Christina Haverkamp lives with the Yanomami Indians in the Amazon Rain Forest. So far she has built 3 small medical stations for these people who previously had no access to health care. She also obtained a donation of insecticide-treated mosquito nets from Bayer Environmental Science to help control malaria, a major health threat to these very vulnerable people.
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he Yanomami Indians belong to the last remaining indigenous people in the world still living the same way they have done for thousands of years. They remained undiscovered and undisturbed until well into the 20th century. Probably never more than 20,000 to 30,000 in number, their habitat covers an area about the size of Switzerland, deep in the Amazon Rain Forest overlapping Brazil and Venezuela. Today, there 52
are about 9000 Yanomami in Brazil and about 15,000 in Venezuela. But since the mid-1980s their survival has been severely threatened, not only by timber and mining industries and speculators buying up land, but particularly by the discovery of gold in this region. In addition to the ensuing destruction of the Yanomami’s natural habitat came the devastating effects of newly introduced diseases.
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NGO
Ideal for mosquitoes As in any population, the Yanomami were previously not spared from diseases, the major burden being parasites. But incomers brought yet more diseases such as tuberculosis, measles and influenza, which the Yanomami had never been exposed to before, often with fatal consequences. Worse, when the gold diggers arrive they fell large tracts of forest to extract this metal from the soil, transforming the area into barren earth pitted with large pools of stagnant water. These muddy swamps are created when washing the extracted gold from the earth, and provide ideal breeding grounds for mosquitoes, the vectors for malaria. In the 1980s as many as 50,000 fortune hunters were illegally extracting gold in the Amazon Rain Forest. Since many of the gold diggers also had malaria, the disease soon spread to the Yanomami. By 1991, 80% of the 6000 surviving Yanomami in Brazil had malaria.
life deep in the Rain Forest to fascinated school children and other audiences. Not only does this open people’s eyes to the problems facing these American Indians, she uses the donations and funds she collects from her arduous tours to bring health care to the Yanomami Indians. In 2006 she founded the charitable organization “Yanomami – Hilfe e.V.” to expand these activities. Building medical stations Following her first visit in 1990, she has repeatedly returned to Brazil bringing rucksacks full of medications to these people. Christina Haverkamp’s
Fascinating world For the last 17 years Christina Haverkamp from Nordhorn (Lower Saxony) in Germany has dedicated most of her time and energy to helping the Yanomami Indians in the Amazon Rain Forest. “The Yanomami have become my life’s work,” she says, as she describes her expeditions and actions to increase public awareness about these indigenous people and their fight for survival. For example, when she crossed the Atlantic on a home-made bamboo raft in 1992, together with the adventurer and human rights activist Rüdiger Nehberg. Planned to coincide with the 500-year anniversary celebrations of the New World, this spectacular expedition from Dakar (Senegal) to Brazil, then on to Washington and the White House aimed to spotlight the continuing suppression of indigenous American Indians. When not spending time with the Yanomami, Christina Haverkamp travels around Europe and America giving talks illustrated by slides, especially to schools. It is clear that the activist originally trained as a teacher when she vividly describes a unique world of customs and ways of
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CHRISTINA HAVERKAMP with a Yanomami boy in the little school of Ixima.
THE CHILDREN and Christina Haverkamp proudly present the newly built medical station in Papiu.
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NGO
DEEP IN THE AMAZONIAN RAINFOREST the Yanomami are among the last remaining indigenous people worldwide retaining their customs and ways of life evolved in harmony with their environment.
long-term goal was to build permanent medical stations for the Yanomami Indians in their own villages. The first medical station was completed in the village of Ixima in 1997. While the upper structure was made from wood and leaves, materials for the concrete and tiled lower part of the building were transported in by plane or boat. This was expensive, but important for the building’s stability and function. The Yanomami enthusiastically helped to build the small two-storey clinic, which includes a school, based on Haverkamp’s own design. “Unlike other medical stations, which heat up like an oven, I wanted it to be relatively open to let air circulate,” she says. In 2001, Haverkamp built a second medical station and school in Papiu Novo, previously a center for the gold diggers. Although political action has now reduced the number of gold diggers to one or 54
two thousand, the burden of diseases remains. She was then approached by a doctor asking for her help to build a station in the Orinoko area in Venezuela. This third station in Mavaquita is the most remote medical care center in the world. Yet for many Yanomami people reaching a medical station still means many days traveling through the forest on foot or by boat. For this reason Haverkamp is still planning further medical stations in Venezuela, as well as completing the mobile station on a boat project. Once an infrastructure is set up, the Yanomami run the stations themselves, supported by the Brazilian or Venezuelan governments who pay for trained medical staff and supplies for these stations. The most important functions are providing vaccinations for children and early treatment of malaria. Eventually, the Yanomami should also carry out the medical treatments once they have gained the necessary skills.
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NGO
Preventing malaria with mosquito nets Christina Haverkamp has had malaria four times, and worries that repeated treatment may no longer work if resistance develops to the medications. So last year she decided to extend the malaria program to providing the Yanomami with mosquito nets. Brazil did not allocate any money for nets so she contacted Bayer Environmental Science to ask for a donation of 2000 insecticide-treated nets. But these could not be “normal” bednets, since the Yanomami sleep in hammocks. So nets were customized in size and shape for use as hammock nets. These impregnated hammock nets were then delivered directly from manufacturers in Thailand and distributed with the help of Bayer Brazil and Yanomami representatives who have learned Portuguese. The first batch of nets was sent to the area of Rio Marauia and a second batch to Kayanau. A major aspect of distributing these nets is showing the Yanomami how to use them properly – having no tradition of using nets for malaria prevention, they also use them for fishing or as children’s toys.
Over the years Christina Haverkamp has learned the Yanomami’s language, customs and traditions and gained their trust. Even the Shamans, the local healers, support the medical stations and modern methods, since they know they can do nothing against diseases such as tuberculosis, river blindness and malaria. “These diseases were brought in by us so we should be helping to treat them,” says Haverkamp. Now with the first batch of donated nets distributed she hopes to see an impact on malaria cases by close monitoring of hospital admissions. More www.yanomami-hilfe.de
HAVERKAMP VISITS different villages to explain how to use the insecticide-treated nets properly – not for fishing, but as hammock nets to protect particularly the children from malaria.
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Article on the enclosed Public Health CD-ROM Photos by Christina Haverkamp
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NOTES
Photo: Elisabeth Friedrich
Kenya study: Malaria bednets key to saving children The risk for children under age 5 of dying from malaria can be cut nearly in half if they sleep under insecticide-treated bednets, a new study in Kenya shows. Over the last three years Kenya has expanded distribution
of bednets and, as a result, fewer children are dying, KEMRIWellcome Trust Research Programme said in the journal Lancet. Quoted from UN Wire
Chikungunya: First infections in Europe Between June and mid-August in 2007 more than 100 infections confirmed by Italian officials as chikungunya occurred near Ravenna in north-east Italy. Spread by mosquitoes, the virus has infected at least 1.4 million people in India and Indian Ocean islands since 2005 (see Public Health No. 18, page 45).
Although previously diagnosed in travelers returning from infected areas, this was the first report of chikungunya arising locally in Europe. Warm weather and more mosquitoes than usual are blamed for the outbreak. The chikungunya vector, Asian tiger mosquitoes, are now widespread in Italy and warmer
regions of Europe and the Americas, although without the virus. In the tropics the same insect also passes on dengue virus to about 100 million people a year. Fears are that both viruses could become established in European mosquitoes. Source: New Scientist
IRAC: Manual on resistance management
Climate change: Malaria rises in Peru
Since 1984 the Insecticide Resistance Action Committee (IRAC) has been dedicated to making effective insecticide resistance management a reality. IRAC’s new brochure highlights the public health importance of preventing and managing insecticide resistance in vectors and pests. Among other things, the manual explains what resistance is, outlines different approaches to resistance
Though malaria was virtually eradicated in Peru more than 30 years ago, the disease has made a serious comeback in the country‘s Amazon region. Tens of thousands of cases are now reported annually, officials say, with loggers and others contemplating the role of climate change, which has led to abnormal rain patterns.
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management and describes monitoring methods and success stories. More www.irac-online.org
Quoted from UN Wire
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NOTES
An increasing problem worldwide: Re-emergence of bedbugs Until the 1940s being bitten by bedbugs was a fairly normal, if annoying, part of everyday life for most of the world’s population. But over the next few decades bedbugs were virtually eliminated from industrial countries through the use of DDT, improved hygiene and increased awareness of the problem. However, bedbugs persisted in the developing world much as before.
refugee accommodation. Camp beds, bedding, tents and clothes provided by aid organizations can also be infested by bedbugs. Another source for contaminating private flats is acquiring secondhand furniture. Every tiny crack and crevice must be scrutinized for signs of fecal matter, eggs or larvae before being taken into the home.
Then in the late 1990s, bedbug infestations started to resurge in the UK, USA and Australia. Cases are estimated to have increased 10-fold since 1999. Of the 89 species from the Cimicidae family only 2 species are ectoparasites of humans, the common bedbug Cimex lectularius, which occurs in most parts of the world, and its tropical relative Cimex hemipterus. Feeding on the blood of sleeping people, they are not known to spread any particular disease, just itchy inflamed spots appearing overnight. Reasons for the re-emergence of bedbugs are mainly attributed to elimination of very long-lived residual pesticides; increased international travel, with bedbugs infesting baggage and airport hotel rooms. Additional reasons are high fluctuations in occupancy of flats, student residences, hostels for the homeless and
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Cimex lectularius
Once established in human habitation, they are extremely difficult guests to get rid off. They burrow and hide in tiny spaces during the day, such as cracks in wooden surfaces, behind picture frames, wall paper or skirting boards, in plug sockets, light fittings and of course beds. Even after taking measures to remove them it is difficult to know if they are gone for good, since adults can survive for several years without a meal. Previously, space spraying used to control malaria (and cockroaches), automatically destroyed bedbugs as well. But the bugs quickly developed resistance and
the insecticides only acted as an irritant bringing them out of hiding. Although spraying still killed mosquitoes, people thought it increased bedbug infestation, so rejected spraying of their homes. This possibly contributed to ineffective malaria control programs in some areas. Today, insect repellents applied to the skin and household insecticides sprayed in possible hiding places are effective against minor infestations. For severe infestations long-lasting residual spraying is necessary, although the insecticide used must first be checked for its efficacy against the target bedbug population. Adding an irritant insecticide such as pyrethrin increases exposure to the residual insecticide by forcing the bugs out of hiding. Long-lasting insecticide treated bednets used to control malaria transmitting mosquitoes also repel and kill bedbugs. It is often reported that the use of such mosquito nets also completely eliminates infestations of bedbugs and head lice. This additional benefit makes these bednets highly attractive in areas infested with bedbugs. More www.who.int/water_sanitation_ health/resources/ vector237to261.pdf
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NOTES
History: Chagas’ new disease The Brazilian physician Carlos Chagas was the first and only person to discover, research and fully document a new infectious disease. He described every stage, from the life cycle and transmission route of the parasitic pathogen to the acute and chronic symptoms in humans. Naturally, the disease was named after him.
B
orn in Oliveira, Munás Gerais, in 1879, Carlos Justiniano Ribeiro Chagas went to medical school in Rio de Janeiro. There he studied microbiology and bacteriology as methods to apply in medical research. After a few years as a practicing physician, he went to work at the Instituto Oswaldo Cruz, founded by Cruz himself. Oswaldo Cruz had gained his reputation through combating epidemics of yellow fever, smallpox and bubonic plague. Chagas was to concentrate on malaria. But on one of his field missions to investigate a supposed outbreak of malaria he discovered a new disease affecting the railway construction workers located in the remote village of Lassance.
vector – reduviid bugs, also known as assassin or kissing bugs, although until 1925 he thought it was due to the bite of the insect. However, two years before Chagas’ death in 1934, Silveira Dias confirmed that infection occured through the insect’s faeces.
Life-long research
A silent tragedy
Chagas showed that like malaria, the disease was caused by a protozoan parasite, which he named Trypanosoma cruzi after his mentor and friend Oswaldo Cruz. He described how it is transferred through an insect
Although first discovered in 1909, it took some 50 years before Chagas’ disease was recognized as a major public health problem, causing more morbidity than malaria in South and Central America. Described
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CHAGAS’ laboratory in Lassance where he encountered the first cases of the disease.
Carlos Chagas
by one book title as “Una Tragedia Silenciosa”, it mainly affects poor rural areas, particularly the children and young adults and causes irreversible damage to the heart and brain. Darwin’s disease? Some historians think that Charles Darwin suffered from Chagas disease. In his diaries during the Beagle voyage Darwin recorded being bitten by a “Great Black Bug” near Mendoza in March 1835. Although still a young man and in good health at the time, two years later, back in England, he began to suffer from an unusual variety of symptoms, which affected his health for the rest of his life. Sources Oxford Concise Medical Dictionary (Oxford University Press) Chambers Biographical Dictionary (Chambers Harrap Publishers)
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Link List With reference to the topics in this issue of Public Health Journal we include a summary of the main Internet links, where you can find further information, the latest reports and statements. AMANET (Africa Malaria Network Trust) www.amanet-trust.org Bill & Melinda Gates Foundation www.gatesfoundation.org CORE Group www.coregroup.org GAVI (Global Alliance for Vaccines and Immunization) www.gavialliance.org GBC (Global Business Coalition) http://www.businessfightsaids.org Global Fund to Fight AIDS, Tuberculosis and Malaria www.theglobalfund.org IVCC (Innovative Vector Control Consortium) www.ivcc.com IRAC (Insecticide Resistance Action Committee) www.irac-online.org LSHTM (London School of Hygiene and Tropical Medicine) www.lshtm.ac.uk LSTM (Liverpool School of Tropical Medicine) www.liv.ac.uk/lstm MCDI (Medical Care Development International) www.mcdi.mcd.org NTDC (Neglected Tropical Disease Coalition) www.neglectedtropicaldiseases.org PMI (President’s Malaria Initiative) www.fightingmalaria.gov PSI (Population Services International) www.psi.org RBM (Roll Back Malaria Partnership) www.rollbackmalaria.org TDR (Special Programme for Research and Training in Tropical Diseases) www.who.int/tdr UNDP (United Nations Development Programme) www.undp.org UNICEF www.unicef.org USAID www.usaid.gov WHO www.who.int WHO (Neglected diseases) www.who.int/neglected_diseases/ William J. Clinton Foundation www.clintonfoundation.org World Bank www.worldbank.org Yanomami-Hilfe e.V. www.yanomami-hilfe.de
Events XVIIth International Congress for Tropical Medicine & Malaria (ICTM2008) September 29 – October 3, 2008 Jeju Island, Korea www.ictm17.org Second International Conference on Dengue and Dengue Haemorrhagic Fever (ICDDHF) October 15-17, 2008 Phuket, Thailand www.dengue2008phuket.com Bayer Environmental Science
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MOSTLY UNKNOWN in developed countries lymphatic filariasis, onchocerciasis
(river blindness), leishmaniasis and Chagas (see bug below) are some of the infectious diseases of poverty that have caused suffering and disability throughout history. Defined as Neglected Tropical Diseases (NTD), recent scientific breakthroughs and corporate or private philanthropy are now providing the tools and resources to combat such diseases.
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