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Aims: The objective of these surveys was to estimate the prevalence of faecal carriage of Salmonella in healthy pigs, cattle and sheep at slaughter, and of pig carcase contamination with Salmonella. These data can be used as a baseline against which future change in Salmonella prevalence in these species at slaughter can be monitored. Methods and Results: In this first randomized National Survey for faecal carriage of Salmonella in slaughter pigs, cattle and sheep in Great Britain, 2509 pigs, 891 cattle and 973 sheep were sampled in 34 pig abattoirs and 117 red meat abattoirs in England, Scotland and Wales. Carriage of Salmonella in 25 g caecal contents was identified in 578 (23AE0% pigs) but in only 134 (5AE3%) of carcase swabs. The predominant Salmonella serovars found in both types of sample were S. Typhimurium (11AE1% caeca, 2AE1% carcases) and S. Derby (6AE3% caeca, 1AE6% carcases). The main definitive phage types (DT) of S. Typhimurium found were DT104 (21AE9% of caecal S. Typhimurium isolates), DT193 (18AE7%), untypable strains (17AE6%), DT208 (13AE3%) and U302 (13AE3%). Three isolates of S. Enteritidis (PTs 13A and 4) and one enrofloxacin-resistant S. Choleraesuis were also isolated. A positive Ômeat-juice ELISAÔ was obtained from 15AE2% of pigs at 40% optical density (O.D.) cut-off level and 35AE7% at 10% cut-off. There was poor correlation between positive ELISA results or carcase contamination and the caecal carriage of Salmonella. The ratio of carcase contamination to caecal carriage rates was highest in abattoirs from the midland region of England and in smaller abattoirs. In cattle and sheep 1 g samples of rectal faeces were tested. Two isolates (i.e. 0AE2%) were recovered from cattle, one each of S. Typhimurium, DT193 and DT12. One sheep sample (0AE1%) contained a Salmonella, S. Typhimurium DT41. In a small subsidiary validation exercise using 25 g of rectal faeces from 174 cattle samples, three (1AE7%) isolates of Salmonella (S. Typhimurium DT104, S. Agama, S. Derby) were found. Conclusions: The carriage rate of Salmonella in prime slaughter cattle and sheep in Great Britain was very low compared with pigs. This suggests that future control measures should be focused on reduction of Salmonella infection on pig farms and minimizing contamination of carcases at slaughter. Significance and Impact of the Study: This work has set baseline figures for Salmonella carriage in these species slaughtered for human consumption in Great Britain. These figures were collected in a representative way, which enables them to be used for monitoring trends and setting control targets.

A 12-month abattoir study was undertaken from January 2003. We collected 7492 intestinal samples from cattle, sheep and pigs at slaughter. Rectal samples were taken from cattle and sheep and caecal samples from pigs. They were examined for verocytotoxigenic E. coli (VTEC) O157, Salmonella, thermophilic Campylobacter and Yersinia enterocolitica. Data were collected on the animal from which the sample came and this information was analysed to look at potential risk factors for carriage of these organisms. Logistic regression models were run where an adequate number of positive results were available. This revealed that VTEC O157 carriage in cattle was associated with the summer period and that age was a protective factor. Salmonella carriage in pigs was associated with lairage times >12 h, the North East and not feeding when there was no bedding available. In cattle, carriage was associated with the summer period, the Eastern region of GB and dairy animals. In sheep a spring seasonal effect was seen, which coincided with the lambing period. The carriage of thermophilic Campylobacter in cattle was associated with single-species abattoirs, with age a protective factor. In sheep, winter was a risk period with lairage management influential. For pigs, lairage times of <12 h were found to be associated with carriage. A seasonal trend for carriage of Y. enterocolitica in all species was demonstrated with the period December-May a risk. For cattle, age was also a risk factor; for sheep feeding in the lairage and for pigs being held overnight were risk factors.

During the decade to 1999, the incidence of human infections with the zoonotic pathogen verocytotoxin-producing Escherichia coli O157 (VTEC O157) increased in England and Wales. This paper describes the results of a survey of 75 farms to determine the prevalence of faecal excretion of VTEC O157 by cattle, its primary reservoir host, in England and Wales. Faecal samples were collected from 4663 cattle between June and December 1999. The prevalence of excretion by individual cattle was 4.2 per cent (95 per cent confidence interval [CI] 2.0 to 6.4) and 10.3 per cent (95 per cent CI 5.8 to 14.8) among animals in infected herds. The within-herd prevalence on positive farms ranged from 1.1 to 51.4 per cent. At least one positive animal was identified on 29 (38.7 per cent; 95 per cent CI 28.1 to 50.4) of the farms, including dairy, suckler and fattening herds. The prevalence of excretion was least in the calves under two months of age, peaked in the calves aged between two and six months and declined thereafter. The phage types identified most widely were 4, 34 and 2, which were each found on six of the 29 positive farms.