Emerging Diseases and Welfare

The Emerging Diseases and Welfare Programme provides scanning surveillance data on endemic diseases and animal welfare of farmed livestock, birds and wildlife in England and Wales, and detects and assesses exotic and novel disease conditions.

VLA received over 38,000 diagnostic submissions in 2007, which is fewer than the previous year mainly due to the effect of the two outbreaks of FMD.

This year we published the first cattle disease surveillance report covering Great Britain and similar reports on other farmed species and wildlife will follow over the next 18 months.

New conditions were detected by our scanning surveillance system, which included Toxocara vitulorum infection in cattle and corvid respiratory syndrome in wild birds. These were referred to the Human Animal Infection Risk Surveillance Group (HAIRS) to assess the implication for human health, but none were considered to pose a significant risk.

The more significant surveillance findings from each species group are detailed below.

Cattle

• Border disease virus was identified as the cause of disease in cattle on three premises in England and Wales. A letter reporting the incidents was published in the Veterinary Record (August 11, 2007) pointing out the implications of this finding for existing eradication and control schemes.
• Toxocara vitulorum infection was diagnosed in two incidents involving young bison and in beef cattle on a farm in South Wales. The latter was the first case diagnosed in cattle in Great Britain and at a latitude of 52º North this indicates the appearance of the parasite above the published range, a feature which may be related to global warming.
• Traumatic reticuloperitonitis was identified as a common cause of disease and death in adult cattle, particularly in the South West. This was frequently associated with the ingestion of ‘tyre wires’ from degenerating tyres used on silage clamps and in some cases from metal fragments from feeder wagons.

Small Ruminants

• Haemonchosis was a common and significant problem, particularly in the South and Midlands. Haemonchus contortus worms are prolific egg producers and pastures can become very heavily contaminated in a short period of time. This leads to severe acute outbreaks of anaemia and mortality, in all ages of sheep.
• The number of incidents of chronic fasciolosis (liver fluke infection) at the beginning of the year was lower than the previous eight years. However, the wet weather experienced in May and June was conducive to completing the parasite’s life cycle. There were consequently significantly more incidents of acute fasciolosis in the autumn and winter than each of the last four years.
• Osteodystrophic conditions occurring in overwintered sheep in the North West were investigated and attributed to vitamin D deficiency.

Pigs

• Respiratory disease in growing pigs continued to be a major problem for pig herds. The porcine reproductive & respiratory syndrome (PRRS) virus was found to be an important causative agent often together with other pathogens, notably porcine circovirus type 2 (PCV-2).
• Good progress is being made with a collaborative project with Roslin Institute, Genus, PIC and Sygen studying the immunogenetics of breed susceptibility to PRRS. A recently completed project identified the genotypic changes in the virus which have occurred since its introduction to Great Britain.
• VLA is working with the British Pig Executive (BPEX) and the Cambridge Infectious Disease Consortium to investigate the causes of pleuritis in growing pigs. This condition, which was detected by abattoir surveillance, results in financial loss due to the downgrading of the affected carcases.

Birds

• H7N2 avian influenza virus was identified in a small flock of chickens as a result of scanning surveillance samples being submitted to VLA. Notification to the Animal Health agency initiated further tracing which revealed another group of affected birds in the North West.
• An avirulent strain of Newcastle disease was identified following screening of a flock of outdoor broiler chickens for evidence of IBV.
• A strain of IBV which demonstrated a close genetic relationship with the so-called Chinese QX strain, was isolated from a Peking bantam in a backyard flock in South East England. This is the first report of the presence of this virus in the United Kingdom.
• Collaboration with a large poultry veterinary practice has laid the foundation for importing disease surveillance data to enhance the surveillance of poultry diseases.

Miscellaneous and Exotic Species

• TB caused by both Mycobacterium bovis and M.microti was diagnosed in New World camelids. This was one of the issues discussed at the first Defra camelid stakeholder group in September.
• Attaching and effacing E.coli (AEEC) were identified as causing intestinal lesions in three alapca. This is the first description of AEEC associated lesions in New World camelids.

Wildlife

• The VLA Wildlife Group is investigating a disease syndrome causing deaths in rooks and crows, which has been termed ‘Corvid Respiratory Disease Syndrome’. Preliminary results indicate the involvement of P. multocida and mycoplasma spp. and the pathological changes show similarities to those of fowl cholera in chickens.
• Investigations were carried out into the seabird mortalities associated with the wreck of the container ship, MS Napoli, on the Devon coast.
• The deaths of 600 waterfowl on the lake in St James’s Park, London were found to be caused by a combination of botulism and lead poisoning.

Animal Welfare

• Forensic pathology support was provided for ten prosecutions under animal welfare legislation.
• Welfare advice was given as part of 31 farm investigational visits.
• Welfare surveillance reports included an analysis of the effects of the severe flooding experienced during the year.