Emerging Diseases and Welfare
The aim of the Emerging Diseases and Welfare Programme is the supply of high quality information to Government and other customers on the disease status of farmed livestock and birds in England and Wales.
Programme Manager
VLA Regional Laboratories continue to attract large numbers of diagnostic submissions from private veterinary surgeons with 41,298 diagnostic submissions being processed during the year. There was continued increase in the proportion of diagnostic submissions presented as carcase material together with an increase in the number of submissions from miscellaneous and exotic farm species and wildlife.
Cattle
A fifth outbreak of Bovine Viral Diarrhoea (BVD) type II was investigated in Shropshire and a risk assessment for the possible impact on the national herd, was produced.
There was an increase in the number of incidents of fasciolosis in cattle in 2005 compared to the previous year and a paper describing the emergence of fasciolosis in East Anglia was published. Tick borne diseases, notably Babesiosis, also increased and cases were reported in areas where the disease had not previously been recognised. Another notable tick related incident was the investigation of an outbreak of tick borne fever which was responsible for pyrexia and agalactia affecting 40 out of 78 cows in a Cumbrian dairy herd.
The number of incidents of Johne’s disease in cattle increased this year and continued the overall increasing trend seen over the last five years. An investigational visit to a particularly heavily infected farm identified a number of important risk factors, notably frequent buying-in from a variety of sources, pooling of colostrum, group housing of calves, overstocking and lack of general farm hygiene.
The first description of a bovine skin condition, Epidermolysis bullosa in cattle in Great Britain was reported. A pilot sentinel practice network was established in North Yorkshire as part of a Defra initiative and the project will explore whether usable surveillance data can be collected via practicing veterinary surgeons.
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Small Ruminants
Parasitic gastroenteritis continued to be a significant cause of losses in the sheep industry, and VLA have been working with the Sustainable Control of Parasites in Sheep (SCOPS) group on a range of issues including Nematodirus disease alerts.
(vertical bars represent 95% confidence limits)
An unusual encephalopathy characterised by extensive vacuolation of white matter and laminar cerebrocortical neuronal necrosis was identified in lambs in four flocks. Blindness was the main clinical sign in three of the flocks and water deprivation was considered as a possible aetiology in each of the outbreaks. The number of diagnosed incidents of contagious lymphadenitis (CLA) as a percentage of diagnosable submissions has increased over recent years. The reason for the increase is unclear, although increased awareness of the disease, and the launch of a monitoring scheme in Scotland may have contributed.
A group of orphan lambs, treated every 35 days were suspected of developing moxidectin resistance, where ill thrift and death occurred. Further more detailed investigations are on-going.
Pigs
Porcine Circovirus (PCV2) -associated diseases continued to underline much of the disease occurring in pigs from weaning to slaughter. Post-weaning Multisystemic Wasting Syndrome (PMWS) within the first few weeks after weaning was less commonly seen, whereas disease in older pigs had a major economic impact on some units. Preliminary findings from an investigation of 27 incidents of deaths in growers and finishers between 10 and 20 weeks of age indicated that high mortality, regardless of a variety of diagnosis and presenting clinical signs, often involve PCV2-associated disease.
Research into the emergence of novel strains of Porcine Respiratory and Reproductive Syndrome virus (PRRSv) in Great Britain has demonstrated considerable variation among recent isolates. Phylogenetics analysis revealed one group to be very similar to viruses isolated in the early 1990s while the remainder are very different, forming several divergent branches.
A BBSRC project, to investigate the host responses of various pig breeds to infection with PRRSv is ongoing. A study using pregnant sows, previously identified as ‘highly’ and ‘poorly susceptible’ during in vitro trials, to examine the reproductory component of the disease is also underway.
Back to topMiscellaneous and Exotic Farm Species
A first report of BVD virus infection causing disease in alpaca in the UK came via an investigation by VLA Shrewsbury. Genotyping of the isolate showed it as Type 1b and follow-up epidemiological studies are in progress. Tuberculosis caused by Mycobacterium bovis was diagnosed in an eland and ferrets.
An outbreak of Yersinia pseudotuberculosis infection in a colony of guinea pigs was reported and the source of the infection was thought to be contamination of feedstuffs with bird faeces. A control regime was put in place in conjunction with the local public health authorities.
Back to topBirds
An investigation was carried out into the re-emergence of Salmonella gallinarum (fowl typhoid) in a large layer unit. The number of incidents of Blackhead declined compared to previous years. The anticipated increase in this and other protozoal diseases, following the withdrawal of products specifically licensed for their control, have not so far materialised. No further incidents of turkey air sacculitis/meningitis syndrome identified in 2004 were diagnosed. The most likely causative agent is still considered to be Mycoplasma gallisepticum infection. VLA Winchester were involved in the notification and subsequent diagnosis of Newcastle disease in Gamebirds in the Southeast.
Back to topWildlife
(Fringilla coelebs)
VLA received over 650 submission of wild birds during the year, principally for the surveillance of West Nile virus and Avian Influenza. However, numerous other diagnoses were made; one particular mass mortality incident in water birds was found to be caused by necrotic enteritis affecting Whooper (Cygnus cygnus) and Mute (Cygnus olor) swans. Salmonella Typhimurium 56 variant, was isolated from diseased garden birds such as greenfinches, sparrows and chaffinches and also reported was a novel disease causing oesophageal lesions in affected birds. Trichmonad parasites were found associated with the lesions.
Back to topPublic Health
Animal disease surveillance activities resulted in a number of conditions being considered by the Health Protection Agency Human & Animal Infections Risk Surveillance Group (HAIRS). These included Salmonella typhimurium PT40 and 56 infections in garden birds. Corynebacterium pseudotuberculosis, TB in cats, Salmonella Typhimurium PT U288 in pigs, Mycoplasma bovis, meningitis in calves and Airsacculitis/meningitis in turkeys.
Back to topAnimal Welfare
VLA Regional Laboratories continue to provide forensic pathology support to the State Veterinary Service, Local Authority Trading Standards and the RSPCA in bringing animal welfare prosecutions.
Welfare advice was given as part of the outcome of 47 investigative farm visits. In one particular case, a farm investigation related initially to Salmonellosis was referred to the local Animal Health Divisional Office (AHDO) after concern was expressed about overall cow condition. The farm had adopted a novel ‘New Zealand style’ grazing system. Visits to poultry farms associated with the Bristol University Leg Health and Welfare in Commercial Broilers project were completed successfully and a total of 206 visits to 151 different farms had been carried out.
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