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Surveillance

Surveillance APHA disease surveillance report

Disease surveillance in England and Wales, July 2016 n Current and emerging issues n  Highlights from the scanning surveillance network n Update on international disease threats n Botulism outbreaks in wild waterbirds These are among matters discussed in the Animal and Plant Health Agency’s (APHA’s) July disease surveillance report

Current and emerging issues Lumpy skin disease

An updated outbreak assessment on lumpy skin disease in south-east Europe is available at www.gov.uk/government/ uploads/system/uploads/attachment_data/ file/534403/update-lumpy-skin-se-europe. pdf (see below for more information).

Online disease testing A new service has been launched to allow vets in England and Wales to submit disease diagnostic information and receive test results online. The service is known as the APHA Animal Disease Testing Service, and will eventually replace the existing paper-based process for sending in sample data and receiving results. Vets in England and Wales will be able to send, receive and track their livestock diagnostic testing information direct from the office or while out in the field using their mobile or tablet. See www.gov.uk/animal-diseasetesting for details on registering, or e-mail [email protected] for more information.

Highlights from the scanning surveillance network Cattle

Bovine viral diarrhoea A recent investigation by the APHA Penrith Veterinary Investigation Centre (VIC) identified the source, key epidemiological

features and the potential problems associated with the introduction of bovine viral diarrhoea (BVD) virus into a naive herd. Three calves born in a 200-cow milking herd showed an unsteady gait and had an abnormal head posture. The last of these, a one-week-old calf, was examined postmortem. This revealed that the cerebellum was malformed and the vermis was absent. Histopathology confirmed cerebellar dysplasia and loss of myelin evidenced by special staining. Although this manifestation of disease is typical of BVD infection, testing for pestivirus infection by PCR on the spleen and by immunohistochemistry on the brain of the affected calf was negative, reflecting the timing of infection of the calf when in utero. Exposure to BVD virus (BVDV) in the first trimester of pregnancy often results in embryo loss, but in some cows the fetus survives to term and is born persistently infected (PI) by BVDV. These PI animals are the principal source of BVDV infection to other cattle. Such animals can be stunted and illthriven, or they may be indistinguishable from uninfected animals. Infection with BVDV after the first trimester, when the fetus is developing its immune response, can result in the cerebellar dysplastic pathology identified in the calf in this case, and such animals are usually BVDV negative.

The affected herd had three bulls which were used in addition to artificial insemination. Between September and November 2015, the bulls were loaned to two other farms on which active BVD infection was known to be present. The contact with BVD-infected stock by the bulls, followed by return to the home farm and mixing with the milking herd, was considered the most likely route by which infection was introduced as there was no other contact with susceptible animals. The impact of BVD infection entering any, and especially a naive, herd is well recognised and vets and farmers are encouraged to support the English cattle industry’s recently launched BVDFree campaign. Details can be found at www.bvdfree.org.uk. A similar project is planned to start in Wales early in 2017. The English and proposed Welsh campaigns follow comparable protocols to those that have been running in Scotland for the past six years, and in Northern Ireland since 2013.

Small ruminants

Clostridium perfringens type D enterotoxaemia Clostridium perfringens type D enterotoxaemia or ‘pulpy kidney’ is currently the third most commonly Veterinary Investigation Diagnosis Analysis (VIDA)-diagnosed cause of death in growing lambs after parasitic gastroenteritis and coccidiosis. During the months of May and June 2016, pulpy kidney was diagnosed 14 times in England and Wales in growing lambs, and on five occasions in goats. In one of these cases, an unusual clinical manifestation of this disease was observed in a ewe that was submitted to the APHA Thirsk VIC to investigate neurological signs and recumbency affecting several of a flock of 620 ewes. At postmortem examination, the cerebral August 6, 2016 | Veterinary Record | 141

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Surveillance cortices appeared flattened and there was no autofluorescence under ultraviolet light to suggest cerebrocortical necrosis. The other body systems were unremarkable. Severe, multifocal, symmetrical, acute necrosis, with cerebral oedema and vasculopathy were identified by histopathological examination. The lesions in the brain reflected vascular injury leading to necrosis, with the distribution of lesions most suggestive of C perfringens type D epsilon toxin damage/injury. The vaccination history of the flock against clostridial disease was unknown, and the case was unusual as clostridial disease usually presents as sudden death. Several multivalent vaccines are available for clostridial diseases in sheep, including lamb dysentery, tetanus, pulpy kidney, black disease, blackleg, struck and braxy. Flock health plans should include a vaccination protocol for breeding ewes to ensure adequate accumulation of protective immunoglobulins in colostrum and also should indicate appropriate timing of vaccination of growing lambs to ensure their ongoing protection from these ubiquitous diseases. Goats do not appear to respond as well to vaccination as sheep, and more frequent boosters may be required. The use of vaccines against only C perfringens type C and D and tetanus may be preferable. In addition, very few veterinary medicines have a marketing authorisation (ie, are licensed) for use in goats in the UK, and consultation with vaccine manufacturers and application of the cascade can assist in the development of appropriate vaccination protocols for goats.

Pigs

Klebsiella pneumoniae septicaemia outbreaks in piglets Two outbreaks of septicaemia due to Klebsiella pneumoniae subspecies pneumoniae (Kpp) causing sudden deaths of preweaned piglets were diagnosed in early July, both on outdoor units in the East Anglian region. These are the first outbreaks in 2016 and fit the seasonal pattern of Kpp outbreaks over the summer months which have been seen each year since disease due to Kpp sequence type 25 emerged (Fig 1). In one of the outbreaks, six well-grown piglets were submitted to investigate sudden death in two-and-a-half- to threeweek-old pigs in four of 30 gilt litters. Over the previous two weeks, there had been a few deaths in that age of pig, which were not investigated. Gilts are individually paddocked to farrow and the affected paddock area was used in 2015 without disease. However, Kpp outbreaks in piglets had been diagnosed in previous years on other areas of the farm. The pigs showed skin reddening of ear pinnae and ventral abdomens, excess serous fluid in body cavities with fibrin stranding and dark 142 | Veterinary Record | August 6, 2016

FIG 1: Seasonality of Klebsiella pneumoniae subspecies pneumoniae septicaemia outbreaks in pigs from 2011 to July 2016 (2016 data incomplete)

red mesenteric lymph nodes. One piglet had extensive dark red spots in the kidney cortex and another had diffuse petechiation over both kidneys. Cultures from livers, meninges, lungs and peritoneums of five piglets yielded pure growths of Kpp while, from one piglet, Streptococcus suis serotype 1 was isolated from similar sites. This illustrates the importance of laboratory testing to establish a diagnosis, as lesions were similar in the piglets even though one had a septicaemia due to a different pathogen. The second outbreak was diagnosed when pure growths of Kpp were isolated from the livers of three piglets examined by the attending veterinary surgeon following on-farm postmortem examination. Ten piglets between 10 and 20 days old had been found dead with lesions consistent with septicaemia in a batch of about 1000 of this age; this farm had not had previous diagnoses of Kpp septicaemia. In both outbreaks, the Kpp isolates were sensitive in vitro to all the antimicrobials tested except ampicillin to which this organism is innately resistant. Disease has been selflimiting on several units and interventions which have been attempted are described together with the features of past outbreaks on this link: http://ahvla.defra.gov.uk/ documents/surveillance/diseases/klebsiellavets.pdf.

Poultry

‘Spotty liver’ in layer chickens ‘Spotty liver’ is a condition named after the typical gross liver lesions described and is seen sporadically in free-range and organic layer hens, usually at around the time of peak lay. The APHA investigated disease in several free-range and organic layer flocks aged approximately 30 to 32 weeks which experienced a slight rise in mortality lasting for seven to 10 days

following a period of warm weather and heavy rain storms. Two of the affected farms were in quite close proximity. Postmortem examination revealed enlarged livers with multifocal fawn- to cream-coloured liver lesions measuring 1 to 3 mm in diameter (Fig 2). Histological examination revealed multifocal acute hepatic necrosis with little inflammation, suggestive of the effects of bacteria or their toxins, but routine bacteriological cultures of the liver lesions were unrewarding. A tentative diagnosis of ‘spotty liver’ was made taking into account the clinical history of the cases, the gross and histological liver lesions and the unrewarding routine bacteriological results. A novel thermophilic Campylobacter species with fastidious culture requirements has been implicated as a possible causative organism for the disease (Crawshaw and others 2015). The epidemiology of the condition is not fully understood. However, good drainage of the birds’ range and preventing access to standing water may help to prevent or control mortality associated with the disease.

Miscellaneous and exotic farmed species Multiple follicular skin cysts in an adult alpaca

Fixed skin samples from a 15-year-old female alpaca with numerous (50 to 100) cutaneous lumps were submitted to the APHA Shrewsbury VIC for histopathological examination. It was the only animal to be affected from a group of 70 and was otherwise apparently healthy and in good body condition. A morphological diagnosis of multiple follicular cysts was made. This condition occurs occasionally in dogs, sheep, humans and horses and has been reported in alpacas, but the aetiology is unclear. Multiple follicular cysts occur in sheep and Newkirk

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Surveillance Foot-and-mouth disease Turkey has reported further FMD outbreaks, with 260 outbreaks reported so far this year on the Asian side of the country, which is considered endemic for FMD. These outbreaks tend to be reported en masse. The risk level of introduction of FMD to the UK has not changed: there is a continual, albeit variable, low risk of FMD incursion to the UK from any affected region, due to the range of animal products and species which are susceptible to FMD and which may be consigned in good faith, or which may enter the UK in personal luggage. Therefore, an important risk management action is to enforce the swill feeding ban on farms, whether commercial or smallholding.

Lumpy skin disease

FIG 2: Typical lesions of ‘spotty liver’ in a free-range layer chicken

and Frank (2011) described them in aged (10 to 15 years) alpacas; they suggested that the fibre type or repeated shearing may contribute to the development of these lesions. Other clinical differential diagnoses for skin nodules in alpacas include fibromas, fibropapillomas, melanocytomas, trichoepitheliomas, lymphomas, collagenous hamartomas and hair follicle hamartomas. It is therefore important that biopsies are performed on all skin masses to confirm the diagnosis.

International disease monitoring Defra’s International Disease Monitoring (IDM) team’s horizon-scanning activities monitor for major, notifiable or new and re-emerging animal disease outbreaks worldwide. This is done to provide an early warning and to assess the risks they may pose to the UK, in particular those diseases which impact on animal health and welfare, international trade, public health or wider society. The IDM team also assesses the risk that animal diseases might come into the UK through the trade in animals or animal products (legal or illegal), through movements of wildlife, or through the movement of fomites and vectors, such as insects, which may carry infectious disease. These outbreak assessments are used to guide decisions on how to manage or reduce the risks and are published online at www. gov.uk/government/collections/animaldiseases-international-monitoring The following summarises outbreaks during June 2016.

Lumpy skin disease (LSD) has now spread into Albania and Kosovo and further into Serbia. The whole of Bulgaria has been declared a restriction zone to enable vaccination of cattle. Increasing temperatures are expected in the region so numbers of vector insects (principally biting flies) will continue to increase. Both Greece and Bulgaria are using emergency vaccination under EU rules to control LSD. No specific increase in risk to the UK is indicated, which remains very low as the main pathways are trade in live animals, of which there are very few from the affected region as a whole, and none allowed from regions under restriction. The risk of spread from vectors is considered negligible as this is mechanical transmission and although untreated skins and hides could potentially be infected and consigned to trade in good faith, the likelihood of them coming into contact with livestock in this country reduces the risk considerably. Meat is not a risk product, although semen and milk can be LSD virus positive.

Avian influenza No outbreaks of avian influenza were reported in June in Europe, and all previous notifiable outbreaks in Italy and France have been resolved. France is continuing to repopulate some of the previously affected poultry premises which have been lying fallow for several weeks as part of the eradication plan. In Africa, H5N1 highly pathogenic avian influenza (HPAI) (Eurasian lineage) has continued to spread in Ghana, Nigeria and Cameroon and the Food and Agriculture Organization has indicated that increased vigilance and surveillance are required in these areas. Elsewhere, in Asia, HPAI outbreaks in poultry due to H5N1, H5N2, H5N6 and H5N8 viruses have been reported. Canada has reported H5N2 low pathogenic avian influenza (LPAI) of the North American lineage in a duck fattening farm in Ontario, while the USA has reported H5 LPAI findings in three live bird

markets in the states of Pennsylvania, New York and New Jersey. There are a limited number of wild bird migratory routes from these areas of the USA and Canada to Europe, and in general these concern species of waders that go to the Arctic and breed in Greenland and high Arctic Canada. They are considered unlikely to come into contact with birds migrating across the USA. The risk level for the UK remains low, but heightened.

African swine fever June saw a significant increase in African swine fever (ASF) outbreaks in domestic pigs in eastern EU member states, with Poland reporting their its outbreak on a commercial pig farm, and both Estonia and Lithuania reporting disease in backyard farms (eight in total). The risk level of introduction of ASF to the UK has not changed as a result of any of these outbreaks as they were all in the current restriction zones. This prevents the marketing of untreated or uncertified pig meat from farms in these zones, while live pigs cannot be consigned to other member states.

Bluetongue France has reported three more outbreaks of bluetongue virus serotype 8 (BTV-8) in the past month, one in a calf born to a dam with reported clinical disease over the previous months; the calf died soon after birth. One other outbreak was detected as a result of surveillance and one as a report case. There has been no increase in the size of the restriction zone in France. An updated situation assessment has been produced and can be found at www. gov.uk/government/collections/animaldiseases-international-monitoring. BTV-8 vaccine is available for the GB market, and farmers/livestock keepers are reminded to discuss with their veterinarians whether vaccination would be an appropriate option. More detail on the industry-led JAB campaign can be found at www. nfuonline.com/bluetongue. The risk level of introduction to the UK has increased to medium as the temperature has risen in western Europe so the vector season is well underway. IDM, in collaboration with the Meteorological Office, is monitoring the situation closely, in particular the weather and wind direction in case disease due to BTV-8 re-emerges in northern France, in particular coastal regions. Belgium and Germany are vaccinating livestock in at risk areas, which means there will be reduced likelihood of incursion from these areas.

Chronic wasting disease No further information is available at present on the chronic wasting disease situation in Norway or neighbouring countries. Imports from Norway of live cervids are currently banned. The risk August 6, 2016 | Veterinary Record | 143

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Surveillance level for introduction to the UK is yet to be determined while more information is gathered about the situation in Norway and the possible source and time of introduction into the cervid populations there. A new update has been produced and will be available at www.gov.uk/ government/collections/animal-diseasesinternational-monitoring. The main risk pathways to the UK relate to trade/

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imports in live animals, products of animal origin from infected animals or products which could be contaminated with prions (eg, urine used for lures) or clothing and equipment of hunters or walkers which could be contaminated with soil. Further information is available via the British Deer Society’s website: www.bds.org. uk/index.php/research/chronic-wastingdisease-cwd.

References

CRAWSHAW, T. R., CHANTER, J. I., YOUNG, S. C. L., CAWTHRAW, S., WHATMORE, A. M., KOYLASS, M. S. & OTHERS (2015) Isolation of a novel thermophilic Campylobacter from cases of spotty liver disease in laying hens and experimental reproduction of infection and microscopic pathology. Veterinary Microbiology 179, 315-321 NEWKIRK, K. M. & FRANK, L. A. (2011) Multiple follicular cysts in four alpacas (Vicugna pacos). Veterinary Dermatology 22, 275-278

doi: 10.1136/vr.i4172

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Disease surveillance in England and Wales, July 2016 Veterinary Record 2016 179: 141-144

doi: 10.1136/vr.i4172 Updated information and services can be found at: http://veterinaryrecord.bmj.com/content/179/6/141

These include:

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Disease surveillance in England and Wales, July 2016.

▪ Current and emerging issues▪ Highlights from the scanning surveillance network▪ Update on international disease threats▪ Botulism outbreaks in wild ...
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