Effect of the bluetongue virus on unborn kids and lambs
Last summer, bluetongue virus was detected at a dairy goat farm in the spleens of two out of three aborted kids from a single doe. Several goats had aborted. There have also been reports of low-birthweight lambs where the ewes had shown symptoms of bluetongue several months before the due date for lambing. Pathological examination detected bluetongue virus in the spleen tissue of one lamb that was submitted. Other infectious causes were excluded in both cases.
In December 2023, the first case of an aborted lamb with bluetongue virus was detected. The farm was confirmed to be positive for bluetongue. The ewe had
exhibited clinical symptoms consistent with bluetongue during the pregnancy. Pathological examination revealed no abnormalities in the anatomy of the aborted lamb. The same applies to the case studies described above. In the spring of 2024, monitoring of abnormal aborted lambs showed no evidence of effects due to the bluetongue virus.
As yet, no congenital abnormalities in lambs have been identified as being consistent with a bluetongue virus infection. Incidental cases of brain tissue abnormalities were detected in cattle in 2023 as a result of an infection in the mother animal.
Acute liver fluke infections determined in sheep
Since September, reports of acute liver fluke infections have been received through GD’s Veekijker. Pathological examinations during the same period also identified infections with liver flukes. The amount of precipitation and the temperatures during the past year were favourable for the development of liver flukes and the intermediate host snail. In the past, the Liver Fluke Forecast Working Group issued annual provisional (mid-September) and final (mid-November) forecasts based on various findings and data, including snail counts and determination of the infectious stages of the liver fluke in the snails. The activities of this working group were halted in 2020, meaning that there is no longer a clear picture of what livestock farmers can expect in terms of liver fluke disease and the occurrence of resistance to triclabendazole, the only substance that is active against all stages of the liver fluke.
Acute liver fluke disease is a serious condition in sheep caused by the liver fluke parasite Fasciola hepatica. This parasite infects the livers and bile ducts of sheep, causing inflammation and tissue damage. Acute liver
fluke disease can occur after infection with large numbers of larvae after grazing on infected pastures. Symptoms include sudden weakness, high fever, pale mucous membranes, reduced appetite, emaciation and (sometimes) acute mortality. Liver fluke infections in which only adult flukes are present are called chronic infections. The symptoms are less acute but can still be very severe in a flock. In addition to the symptoms listed above, chronic infections can lead to abortions in pregnant animals.
Prevention focuses on avoiding grazing in infected pastures from mid-August onwards. GD advises being alert to the possibility of liver fluke disease in sheep. Alertness to the symptoms of liver flukes combined with blood tests on animals in their first grazing season can detect infections at an early stage. In acute liver fluke infections, pathological examination can give a definite result. Chronic infections can be detected by manure testing. Evidence of liver fluke disease is sometimes found in the slaughterhouse. Feedback to the sheep farmer about the findings is desirable in such cases.
Animal health monitoring
Royal GD has been responsible for animal health monitoring in the Netherlands since 2002, in close collaboration with the veterinary sectors, the business community, the Ministry of Agriculture, Fisheries, Food Security and Nature, veterinarians and farmers. The information used for the surveillance programme is gathered in various ways, whereby the initiative comes in part from vets and farmers, and partly from Royal GD. This information is fully interpreted to achieve the objectives of the surveillance programme – rapid identification of health issues on the one hand and monitoring trends and developments on the other. Together, we team up for animal health, in the interests of animals, their owners and society at large.
The role of Mycoplasma spp. in respiratory tract infections in kids
Investigations of the causes of mortality in young lambs and kids show that respiratory tract disorders are a common problem as they grow. Bacteria such as Pasteurella multocida and Mannheimia haemolytica often cause respiratory tract infections in kids, leading to severe respiration problems and reduced growth. Risk factors include colostrum management, housing and climate.
GD regularly receives questions about the role of Mycoplasma spp. associated with
respiratory infections. Various non endemic Mycoplasma species are known primarily to cause respiratory problems; however, the role of several other Mycoplasma species in respiratory issues is less evident. Diagnosis of respiratory problems is complex as the main bacterial pathogens are often present even when there are no signs of disease. In cases of infections where the response to treatment is poor, questions arise as to what other pathogens might be playing a role in the infection. Techniques such as culturing
or PRC will confirm its presence but not its causal role in pathogenesis. New diagnostic techniques such as nanopore protein sequencing are improving our understanding of the variation in respiratory pathogens in the lambs and kids. This may lead to better prevention and treatment of respiratory tract disorders. Next spring, as part of its monitoring task, GD will start a pilot looking at the pathogens of respiratory problems in kids and lambs submitted for pathological examination.
Photosensitisation in sheep in the central Netherlands
In late October, the Veekijker received several reports from veterinarians diagnosing skin problems in sheep. Further investigations, including liver enzyme analyses and inspection of grass samples, confirmed sporidesmin intoxication in several cases. The Veekijker received these signals from veterinary practices in the central Netherlands.
Since 2019, the Netherlands has recorded cases annually of photosensitivity in sheep caused by sporidesmin intoxication. This hepatotoxic compound is produced by the fungus Pithomyces chartarum, which thrives on dead plant material in warm, humid conditions (over 90% humidity and a daily minimum temperature of 12-15 degrees Celsius). Just a few warm, humid days are
sufficient for the fungus to begin sporulating. For cases of sporidesmininduced skin problems in sheep, GD advises conducting blood tests to assess liver function.
BTV-12 detected in sheep and cattle in the Netherlands
In September, the Veekijker investigated a case involving a ram displaying symptoms of bluetongue, but there was doubt whether this was actually caused by BTV-3. GD contacted Wageningen Bioveterinary Research (WBVR) and alerted them to the sample in question with a request to examine this sample for other serotypes too. Further typing showed that the disease was caused by serogroup 12. This serogroup has not previously been detected in Europe but is seen in some countries outside Europe. Following this initial finding, a retrospective study was carried out within a twentykilometer radius of the farm where this ram
was located. This revealed a heifer and her calf that were also infected with BTV-12, on a dairy farm within a five-kilometer radius. After BTV-12 was detected at these first two farms, the extent of the occurrence of BTV-12 was investigated by further retrospective studies on blood samples submitted from 1 September onwards because of suspicions of BTV. A total of 2520 samples submitted between 13 September and 11 October were retested to see if either BTV-3 or BTV-12 was present. Eleven samples were positive for BTV-12. Various farms were in the vicinity of the first two cases and BTV-12 was also detected in Landsmeer,
Dronten and Laag-Keppel. BTV-12 is a new serotype with as yet unknown characteristics but the number of infections remains limited for now. In addition, the downward trend in new reports of bluetongue is continuing; the number of sheep carcasses collected by Rendac has fallen sharply since september. Although the number of dead cattle picked up has also fallen, it is still higher than in the same period in 2022, when bluetongue did not yet occur in the Netherlands.
As yet, there are no clues suggesting the source of BTV-12 in the Netherlands.
Animal health barometer – Small Ruminants
Disease/disorder/ health characteristic
Articles 2.1.a and 2.1.b of the Designation of Animal Diseases in the ‘Rules for Animal Health’/Implementing Regulation (EU) 2018/1882 of the Animal Health Law (EU) 2016/429 (Category A diseases)
Infectious pleuropneumonia in goats (CCPP)
(Mycoplasma capricolum subs . capripneumoniae)
Never detected in the Netherlands.
Foot-and-mouth disease (FMD) FMD has not been reported in the Netherlands since 2001.
Infection with goat plague (a.k.a. PPR, peste des petits ruminants)
Infection with Rift Valley Fever virus (RVF)
Never detected in the Netherlands. Ongoing outbreak since July 2024 in parts of Greece and Romania. The number of infections is growing despite restrictive measures.
Never detected in the Netherlands.
Sheep pox and goat pox (SGP) Never detected in the Netherlands. Multiple outbreaks have been detected at sheep farms in Spain from September 2022 to the spring of 2023. From October 2023 onwards, multiple outbreaks have been confirmed in Greece. The infection has in the meantime spread to Bulgaria.
*
A+D+E * *
Articles 2.1.a and 2.1.b of the Designation of Animal Diseases in the ‘Rules for Animal Health’/Implementing Regulation (EU) 2018/1882 of the Animal Health Law (EU) 2016/429 (Categories B to E)
Infection with Brucella abortus, B. melitensis
Infection with the rabies virus
Infection with the bluetongue virus (serogroups 1-24)
The status of the Netherlands is ‘disease-free’. Monitoring is done annually on sheep and goat farms (a minimum of 1,475 farms) by taking blood samples. Acquiring the requisite numbers has proved challenging over the last two years.
Detected very rarely in bats. Recently detected in a cat in the northern Netherlands.
The Netherlands has been tackling an outbreak of BTV-3 since September 2023. BTV-12 was detected in the Netherlands in October, so far in eleven animals at eight locations.
BTV-3 is widespread throughout Europe. Infections have also been detected in the UK.
There is an outbreak of BTV-8 in France leading to more clinical complaints than the outbreak that has been ongoing since 2015. The two BTV-8 serogroups detected are genetically different.
BTV-1, BTV-3, BTV-4 and BTV-8 have been shown to be circulating in Spain.
B+D+E *
B+D+E
Disease/disorder/ health characteristic
Epididymitis in sheep (Brucella ovis)
Infection with Mycobacterium tuberculosis complex
(M. bovis, M. caprae, M. tuberculosis)
Anthrax (Bacillus anthracis)
Paratuberculosis (Mycobacterium avium subs. paratuberculosis)
Q fever (Coxiella burnetii )
Brief description
Examination of rams for export purposes. Not previously confirmed in NL.
The Netherlands has been officially free of bovine tuberculosis since 1999.
Last registered outbreak in cattle in 1993. No infections detected since then.
Regular cases, largely in goats (inc. dairy) and occasionally in sheep.
The Q fever bacterium was detected in April in a bulk milk sample from a dairy sheep farm. Secretion was demonstrated in yearlings that had not been vaccinated against Q fever despite it being mandatory. The final dairy goat farm with C. burnetii was certified free from infection in 2016.
Echinococcosis An echinococcus cyst was detected during pathological examination of a sheep in April 2023. The specific type is not known.
Trichinellosis No known cases of trichinellosis in sheep or goats.
Article 2.1.c Designation of animal diseases in the ‘Rules for Animal Health’ of the Dutch Animals Act Transferable TSEs (scrapie, BSE)
Hardly any cases among sheep in the past ten years. In goats, the first case of scrapie was in 2000 and the last in 2001.
Article 3a.1 Notification of zoonoses under the ‘Rules for Animal Husbandry’ of the Dutch Animals Act
Campylobacteriosis (Campylobacter spp.)
Leptospirosis (Leptospira Hardjo)
Listeriosis (Listeria spp.)
A few cases per year. Particularly known as a cause of abortion in small ruminants.
Not previously confirmed in NL. Indications of Leptospira spp. were found in February 2024 in the liver tissues of aborted lambs. The diagnosis could not be confirmed because the livestock farmer did not want to cooperate with the follow-up diagnostic testing.
Encephalitis caused by Listeria monocytogenes is regularly found in sheep and especially in dairy goats. Problems caused by listeriosis are reported at a few dairy goat farms each year. How long listeria bacteria are excreted into the milk for is not known.
Both L. monocytogenes and L. ivanovii can cause abortion in sheep and goats.
*Further investigation into the types found in humans and animals is desirable.
Disease/disorder/ health characteristic
Salmonellosis (Salmonella spp.)
Yersiniosis (Yersinia spp.)
Toxoplasmosis (Toxoplasma gondii )
Other OIE list diseases
Enzootic abortion (Chlamydia abortus)
Caprine arthritis encephalitis (CAE)
Brief description
Since 2016, there have been recurrent and large-scale losses of kids at dairy goat farms, caused by a multiresistant S. Typhimurium. There also were multiple cases of illness in humans caused by the same MLVA strain of the bacterium.
Infections are occasionally detected in young kids on dairy goat farms. The progression of the symptoms can be very serious. * * A further study of dairy goats is underway within the framework of public-private partnership, looking at increased sustainability of dairy goat farming.
A few cases per year. Identified as a cause of diarrhoea, mortality and abortion.
Only a few confirmed cases per year but probably one of the most commonly occurring causes of abortion. High seroprevalence has previously been demonstrated in sheep and goats.
One of the main causes of abortion in goats and sheep for many years. Distribution from farm to farm is through contaminated female breeding stock. Very difficult to tackle once introduced to a flock.
Commonly occurring disease in which the pathogenic virus sometimes behaves differently depending on the size of the farm. Source of introduction not always clear.
Maedi-visna virus (MVV) A significant infectious disease (or the most significant) at sheep farms, larger ones in particular.
Tularaemia (Francisella tularensis)
Mycoplasma agalactiae
Nairobi sheep disease
Heartwater (Ehrlichia ruminantium)
Infections with Schmallenberg virus (SBV)
Since 2011, infected hares have regularly been found in the Netherlands, as well as a small number of human tularaemia patients.
Never detected in the Netherlands.
Never detected in the Netherlands.
Never detected in the Netherlands.
Has been detected virtually every year since 2011 as a cause of congenital abnormalities in lambs. It has been detected as the cause of congenital abnormalities in both lambs and kids in 2024. Excluding other possible causes of such congenital abnormalities in lambs remains important for early detection of the introduction of other viruses from the Bunyaviridae group, which can lead to the same external clinical deformations. The UK reported an elevated incidence of SBV early in 2024.
Disease/disorder/ health characteristic
From monitoring
Haemonchosis (Haemonchus contortus)
Liver fluke (Fasciola hepatica)
Carcinogenic abnormalities of the udder skin in dairy goats
T. +31 (0)88 20 25 575
info@gdanimalhealth.com www.gdanimalhealth.com
Brief description
During the summer months of 2024, very serious infections were observed in sheep caused by haemonchosis. This gastrointestinal worm infection led to acute mortality on several farms. In addition, co-infections with bluetongue were frequently detected.
In the autumn, several animals were determined upon necropsy to have had acute liver fluke infections. The wet spring led to favourable conditions for liver fluke parasite. Farmers need to be alert to the possibility of liver fluke. Screening lambs for antibodies reveals the infection in good time.
Mild to severe skin lesions were detected in 15% of the flock on a dairy goat farm, which is suspected to have been spread virally.
Sporidesmin intoxication in sheep There have been some reports of photosensitisation in sheep.
1 Quiet: no action required or action is not expected to result in a clear improvement.
2 Increased attention: alert to an anomaly.
3 Further investigation: further investigation is ongoing or required.
Continuation
