Medicina pediĂĄtrica en pequeĂąos animales
Presentation brochure
Newcastle disease
Author: Kang-Seuk Choi. Format: 17 x 11 cm. Number of pages: 74. Binding: Paperback, wire-o.
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Atlas entirely dedicated to Newcastle disease based on a handy and visual approach of the matter. This handbook has been developed by a prestigious and renowned expert extremely experienced in this topic, being nowadays the chief of the OIE reference lab for this disease. An up-to-date and complete review has been carried out including the most significant contents, such as aetiology, epidemiology, etc. Moreover, it is worthy to mention the information related to clinical diagnosis, especially the excellent images included in this chapter. Besides, vaccination has been perfectly developed in order to provide the main guidelines to avoid failures in this sense and control the situation. The atlas format helps to make the contents understandable and affordable for readers.
Presentation of the book Newcastle disease is a contagious bird disease that affects many domestic and wild avian species in which has a great economic and ecologic impact. Besides, it is transmissible to humans, so that it is convenient to extreme caution and to take appropriate measures to avoid its spreading. This disease supposes a worldwide severe problem in lots of countries in which it has not been completely controlled, thus it is essential to know the most important features which make it very dangerous in poultry farming. Moreover, it has been used as an anticancer agent and a potential biological weapon, so that researches with this virus have been numerous in the last decades. Generally speaking, in veterinary medicine, it is necessary to perform an updated and graphic review about it. To make it easier, the author, a prestigious specialist in this field, has developed a thorough study in a didactic and visual way. The inclusion of images, tables, graphs and even flowcharts focuses the reader’s attention on this topic. These graphic resources are accompanied by a short text to make the handbook understandable. Thanks to this information, the veterinarians will get an overview of the disease and this tool will help them to know and tackle the disease successfully day after day.
Newcastle disease
The author Kang-Seuk Choi DVM, MS, PhD. OIE (World Organisation for Animal Health) expert for Newcastle disease. Chief of OIE Reference Lab for Newcastle Disease, Avian Disease Division, Animal and Plant Quaratine Agency (QIA). Republic of Korea.
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Table of contents 1. Part 1. Aetiology and epidemiology
2. Part 2. Clinical signs, diagnosis and control
Newcastle disease (ND)
Clinical signs
History of the disease
History taking
The taxonomy of Newcastle disease virus (NDV)
Clinical tentative diagnosis
Avian paramyxoviruses Virus morphology Virus pathotype Virus genotype Antigenic variation Resistance to environment Hosts of the disease Outbreak versus control Current geographical distribution Transmission mode Incubation period Morbidity and mortality Immunity and protection
Differential diagnosis Sampling and transport Laboratory diagnostic tests Identification of virulent viruses Newcastle disease vaccine Maternally derived antibody (MDA) Hatchery vaccination Field vaccination on farm Vaccination failure Biosecurity Cleaning and disinfection References
1
Aetiology and epidemiology
Newcastle disease
History of the disease First reported in 1926 in Newcastle-upon-Tyne, England (probably introduced from Southeast Asia). At least for several panzootic events of the disease in poultry industry worldwide.
Table 1. Major panzootic events of ND.
4
Panzootic
Emergence
Widespread route
Period
Virus type involved
1st
Southeast Asia (1920s)
Poultry/meat (?)
1926 to early 1950s
II- IV (class II)
2nd
Middle East (late 1960s)
Psittacine
Late 1960s to late 1970s
V (class II)
3rd
Middle East (late 1970s)
Racing pigeon
Entire 1980s
VI (class II)
4th
Asia (middle 1980s)
Unknown (?)
1990s to present
VII (class II)
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AETIOLOGY AND EPIDEMIOLOGY
The taxonomy of Newcastle disease virus (NDV) The sole member of APMV-1 in the genus Avulavirus within the Paramyxoviridae family.
Order
Mononegavirales (single-stranded RNA virus)
Family
Paramyxoviridae
Filoviridae
Subfamily
Paramyxovirinae
Pneumovirinae
Genus
Avulavirus
Morbillivirus
Serotype
APMV-1 (NDV) Other APMVs
Bornaviridae
Rhabdoviridae
Respirovirus
Rubulavirus
5
Henipavirus
Figure 1. Taxonomy of NDV (APMV-1).
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1
Aetiology and epidemiology
Newcastle disease
Avian paramyxoviruses At least 12 serotypes recognised, but new serotypes of APMV are being continuously discovered.
Table 2. List of APMV.
Serotype
Chickens
Clinical signs in poultry Turkeys Ducks/geese Ostriches
Pigeons
APMV-1 APMV-2 APMV-3
6
APMV-4 APMV-5 APMV-6 APMV-7 APMV-8 APMV-9 Clinical signs reported
APMV-10
Subclinical infection reported
APMV-11
No reported
APMV-12
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AETIOLOGY AND EPIDEMIOLOGY
Virus morphology Enveloped and pleomorphic (100 nm to 500 nm in size). Negative-sense, non-segmented and single-stranded RNA genome (15,186 to 15,198 nucleotides in size).
N: nucleoprotein P: phospho M: matrix F: fusion HN: haemagglutinin neuraminidase L: large RNA polymerase
7
P protein
Lipid bilayer
Figure 2. Schematic representation of NDV.
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L protein
M protein HN glycoprotein F glycoprotein
Nucleocapsid (viral RNA + N protein)
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1
Aetiology and epidemiology
Newcastle disease
Virus pathotype Determined based on the severity of clinical disease for chicken. At least four pathotypes: asymptomatic, lentogenic, mesogenic and velogenic. Pathogenicity tests include:
8
» Intracerebral pathogenicity index (ICPI) in chickens (method recommended by OIE).
» Mean death time (MDT) in chicken embryos. » Intravenous pathogenicity index (IVPI) in chickens. » Molecular pathotyping test (MPT) based on F0 cleavage site. Often inconsistent pathotyping results among tests.
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AETIOLOGY AND EPIDEMIOLOGY
Table 3. Pathotypes of NDV, based on the severity of clinical disease for chicken. Pathotype
Main tropism*
Respiratory
Digestive
Clinical signs Reproductive
Nervous
Mortality
Asymptomatic
E
-
-
-
-
-
Lentogenic (Lo)
R, (E)
+
-
-
-
+/-
Mesogenic (Mo) Velogenic (Vo)
R
++
-
+
+/-
+
Neurotropic
N, R
+++
-
+++
+++
++
Viscerotropic
E, R, N
+++
+++
+++
+++
+++
9
* E, enterotropic; N, neurotropic; R, respiratory.
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1
Aetiology and epidemiology
Newcastle disease
Table 4. Several pathotyping tests of NDV isolates. Test
Animal
Inoculation
Measurement
Interpretation Vo
Mo
Lo
ICPI
Day-old SPF chickens
Intracerebral
Mean clinical score (8 days)
1.5-2.0
0.5-1.5
< 0.5.
MDT
10 SPF chicken embryos
Allantoic cavity
Mean death time (h)
< 60
60-90
> 90
IVPI
Six-week old SPF chickens
Intravenous
Mean clinical score (10 days)
2-3
0-0.5
0
Test
Measurement Amino acids (aa) at
MPT
Sequencing analysis of F cleavage site
» Position 112-114 » Position 117
10
Interpretation Virulent: Multibasic aa Phe (F)
Avirulent: Monobasic aa Leu (L)
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AETIOLOGY AND EPIDEMIOLOGY
Mo
MDT (h)
IVPI
Vo 3.0
0
ICPI 2.0
Lo 30
1.5
60
1.0
90
0.5
2.0
1.0
0.0
120
0.0
Molecular pathotyping
NDV strain
112
RRQKRF117
Herts’33
112
RRQKRF
Texas GB
112
RRQKRF117
Beaudette C
RRQKRF
Mukteswar
117
112
117
112
GRGGRL117
LaSota
112
GKQGRL
V4
112
GRQGRL117
Hitchner B1
112
GKQGRL
Ulster 2C
117
117
11
Figure 3. Example of NDV pathotyping tests.
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1
Aetiology and epidemiology
Newcastle disease
Current geographical distribution In poultry, ND is endemic in most of countries in Asia, the Middle East, Africa and Central and South America. Sporadic outbreaks were reported in racing pigeons and poultry (especially backyard birds) in many European countries.
20
Currently, no outbreak of the disease in poultry was reported in Australia, USA and Canada. In wild birds, virulent NDVs are frequently detected in wild cormorants in USA and Canada.
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AETIOLOGY AND EPIDEMIOLOGY
EUROPE 1135
42
2188
ASIA
2250
NORTH AMERICA 54
CENTRAL/ SOUTH AMERICA
32
0.6
225
0.7 0.6
EUROPE
2009 2010 2011
1002
0.0
OCEANIA
17.9
AFRICA
21
4
NORTH AMERICA
CENTRAL/ SOUTH AMERICA
680 2009 2010 2011
704
2972
11
2009 2010 2011
25
MIDDLE EAST
2009 2010 2011
1894
44
MIDDLE ESAST
55.7 ASIA
15 17 2009 2010 2011
2009 2010 2011
AFRICA
24.5
Figure 6. Current global distribution of ND in poultry during 2009-2011, based on the statistics of ND cases officially reported to the OIE.
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1
Aetiology and epidemiology
Newcastle disease
Transmission mode Mechanical transmission is the main route of virus spread during epidemic period and endemic regions.
» People: vaccination crews, insemination technician, vaccination team, veterinarian, etc. » Vehicles: trucks for feed delivery, poultry slaughter and waste transport, etc. » Equipments: reused egg trays, etc. Vaccinated infected birds, subclinical birds and wild birds (cormorants, parrots, pigeons, etc.) can serve as a carrier.
22
Live bird market birds from multiple sources and village chickens can be a significant source of virus dissemination. Airborne transmission is rare because the virus is easily inactivated by direct sunlight. Vertical transmission is unlikely to occur but transmission by contaminated hatching eggs may be possible.
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AETIOLOGY AND EPIDEMIOLOGY FAECES/ MANURE INFECTED PREMISE
LIVE POULTRY
VEHICLE/ EQUIPMENT
CONTACT
MEAT AND BYPRODUCTS
23
FEEDING/ DRINKING
DROPLET INHALATION
? CONTAMINATED EGGS
WILD BIRDS
Figure 7. Various transmission modes of ND.
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?
PEOPLE
VECTORMEDIATED
FEED/ WATER PESTS/ INSECTS
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1
Aetiology and epidemiology
Newcastle disease
Incubation period Incubation period varies depending on host and environmental factors such as the virulence and amount of exposed virus, the host species, host age, immune status, coinfection with other pathogens and environmental conditions.
24
In poultry, the incubation period of ND varies from 2 to 15 days (average 5 to 6 days) after natural exposure. The OIE code gives a maximum incubation period of 21 days for regular purposes.
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AETIOLOGY AND EPIDEMIOLOGY
Morbidity and mortality Morbidity and mortality are influenced by host, agent and environmental factors, which include bird species, strain of virus, bird age, immune suppression, coinfections with other pathogens, physical stress, environmental factors, and vaccination practices.
25
In gallinaceous birds (unimmunised chickens):
» Morbidity: as high as 100 % in chickens. » Mortality: ~ 50 % in adults and ~ 90 % in chicks for neurotropic velogenic NDV. ~ 100 % in all ages for viscerotropic velogenic NDV (vvNDV). In pigeons:
» Morbidity: ~ 100 % in young pigeons and ~ 10 % in adult birds. » Mortality: ~ 100 % in young pigeons and negligible in adult birds.
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1
Aetiology and epidemiology
Newcastle disease
Immunity and protection Antibody titers (e.g., NDV HI titers) strongly correlate with the degree of clinical protection against virulent ND.
a % Clinical signs
100
% Mortality 75
26
50 25 0 <1
2.9 ± 1.4
5.2 ± 1.4
HI titer (log2)
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AETIOLOGY AND EPIDEMIOLOGY
b
30 % Egg drop 25 20 15
27
10 5 0 6.6 ± 0.8
7.5 ± 1.0
8.1 ± 1.0
8.6 ± 1.5
HI titer (log2)
Figure 8 (a and b). Example of relationship between NDV HI titers in chickens and clinical protection against highly virulent NDV (KR005 strain, class II genotype VIId).
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2
Clinical signs, diagnosis and control
Newcastle disease
Clinical signs Gallinaceous birds (e.g., chicken) are highly susceptible (up to 100 % mortality). Clinical presentations vary depending on the virus pathotype and bird species (Tables 3 and 7).
28
The severity of the disease varies depending on the immune status (both passive and active immunity). In field, vaccinated laying hens show generally mild clinical signs and egg drop syndrome without mortality.
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CLINICAL SIGNS, DIAGNOSIS AND CONTROL
a
b
1200 1000
TOTAL
Death
800 600 HOUSE 2 HOUSE 1
400
29
Flock size: 38,000 birds. Bird type: broiler. Vaccination: live NDV (spray, 16 days old). Clinical signs: sudden death, depression, diarrhoea and nervous sign (torticollis).
200
Virology: vvNDV isolation. HOUSE 3
0 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
Age (days old)
Serology: HI test. 10 days old: 1.9 Âą 1.2 (log2). 21 days old: 9.9 Âą 1.0 (log2).
Figure 9. Sudden massive deaths (a and b). High mortality, caused by highly virulent NDV, is usually seen in poultry flocks with no detectable or low level immunity.
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2
Clinical signs, diagnosis and control a
Newcastle disease b
30
Figure 10. Severe depression and ruffled feathers. Most of affected chickens show severe depression and ruffled feathers before death (a and b). Cyanosis of wattle and comb are seen in some of affected birds (b).
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CLINICAL SIGNS, DIAGNOSIS AND CONTROL
a
b
31
Figure 11. Transparent secretions seen at early stage of infection (a and b). Such secretions contain a large amount of the
virus, which can be a source of contamination and serve as source of virus spread from farm to farm and flock to flock by mechanical transmission.
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