Quarterly Surveillance Report Pigs: Vol.9 No.2 April - June 2005 - Published Aug 2005 Contents OVERVIEW (here) NOTIFIABLE DISEASES: ZOONOTIC DISEASES: ENDEMIC DISEASES: VLA PIG PUBLICATIONS

Highlights: Second Quarter 2005

• Bovine tuberculosis in pigs in Cornwall

• Thirty four human deaths in China attributed to Streptococcus suis

• More incidents investigated of raised mortality in finishing pigs – often involving the respiratory disease complex

Overview

The Meat and Livestock Commission Economics ‘Pig Market Outlook’ has been replaced by ‘Pig Market Trends’, which is obtainable from http://www.mlceconomics.org.uk/ The GB DAPP (GB Deadweight Average Pig Price) remained fairly steady at 106p/kg dw. Further details on DAPP and various trends are available on BPEX webpages, such as http://www.bpex.org/bphs/default.asp, that provide details of the British Pig Health Scheme.

A new Quality Standard Mark was introduced to help consumers distinguish between British produce and imports. A British Pig Executive (BPEX) study has shown that two thirds of imported pork, bacon and ham do not meet UK minimum production standards.

NOTIFIABLE DISEASES:

No suspect incidents of swine fever or Aujeszky’s disease were reported that required statutory laboratory investigations.

ZOONOTIC DISEASES AND FOOD SAFETY: FOOD SAFETY INCIDENTS

No suspect incidents involving pigs were reported.

SALMONELLAS & SALMONELLOSIS:

Recorded incidents of Salmonella enterica serovar Typhimurium were fewer than for the same quarter for the previous four years. Histogram shows second quarter percentages of relevant submissions with a diagnosis of salmonellosis.

Second Quarter Data For Each Year Vertical bars indicate 95% confidence limits

U288 and 193 were the most commonly recorded definitive types (DTs) this quarter continuing the trend of the last few years. DT104B was recorded more often than DT104 for the first time. Salmonella Choleraesuis was not reported in this quarter, whereas Derby remained the second most commonly isolated serovar in pigs, with occasional Kedougou and Reading also recorded.

No particularly unusual or severe outbreaks of salmonellosis were reported, whereas the association of salmonella infections as an additional pathogen in incidents of postweaning multisystemic wasting syndrome (PMWS) remains a frequent observation.

Zoonoses Action Plan (ZAP, see http://www.bpex.org/zap/default.asp) visit uptake to category 3 herds (with >85% meatjuice samples antibody positive) increased with nine visits carried out by VLA during the quarter. Salmonellas were isolated from 20% of samples collected, with Typhimurium by far the most commonly isolated serovar. In line with general surveillance data, U288 and 193 were the most frequently isolated definitive types. At the ZAP visits, salmonellas were isolated from bird faeces on 25% and from rodent faeces on 50% of farms. Two thirds of the hospital pens yielded positive salmonella cultures.

TUBERCULOSIS

Five pig carcases slaughtered at a Cornish abattoir showed lesions typical of tuberculosis. The lesions were present in the submaxillary, bronchomediastinal and mesenteric lymph nodes of all five pigs, which came from one smallholding. Mycobacterium bovis was isolated. Over the next three weeks six pigs from the same litter showed the same lesions at the abattoir and M.bovis was again isolated. Histopathological examination of samples showed changes typical of tuberculosis with acidfast organisms present.

The owner had only two breeding pigs – a sow and a boar – that had been housed all their lives and bedded on straw. They produced between two to three litters a year that were reared and sold directly for slaughter to the local abattoir. The infected litter was born in September 2004. Both sow and piglets were fed supplementary cows’ milk obtained untreated from a local dairy farm until the piglets were 12-weeks-old. All were moved to an open-sided barn when the piglets were five-weeks old. When the pigs were weaned at 12-weeks of age the sow was moved into the boar pen where she remained for 6 to 8 weeks. There were a small number of cattle present on the farm that were tuberculin tested soon after the discovery of this incident, no reactors were disclosed.

Investigation of the farm of origin of the milk, and a subsequent tuberculin test, did not detect any recent tuberculosis reactors. Calves on the farm were fed waste milk from the same source without any problems. Milk from the same source was also fed to the herdsman’s pigs, which were slaughtered around the same time as the tuberculous pigs but without showing any lesions of tuberculosis themselves.

A large badger sett is in close proximity to the farm buildings, and it is possible that a tuberculous badger died in one of the farm buildings, such as the open-sided barn, and was then eaten by the pigs when they were moved into that shed five weeks after farrowing. Another possibility is that the pig area was contaminated by an infected badger through urine and faeces. However, the route of infection remains undetermined.

The owner decided to cull the sow and boar following significant bovine reactions to the comparative tuberculin test in both animals. The animals were submitted to VLA Truro for necropsy. The sow had multiple caseous foci in right and left retropharyngeal lymph nodes and in the mesenteric lymph nodes. Careful inspection of the udder of the sow was carried out but only small purulent abscesses were detected and histopathological examination indicated that the lesions were atypical of tuberculosis. The boar had multiple caseous foci in right and left retropharyngeal, bronchial, mediastinal, and mesenteric lymph nodes. One caseous abscess was present in the lungs and a granulomatous lesion was found in the liver.

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Source: Veterinary Laboratories Agency (VLA) - August 2005