United Kingdom: 2013 pig abattoir study

On 13 March 2014, a national meeting was held at Stoneleigh Park to discuss the results of a study of Salmonella, Toxoplasma, Hepatitis E virus, Yersinia, Porcine Reproductive and Respiratory Syndrome virus, antimicrobial resistance in Campylobacter and Extended Spectrum Beta-Lactamase E. coli in UK pigs at slaughter.

A total of 645 pig carcases were randomly selected and sampled at fourteen slaughterhouses between January and May 2013. The slaughterhouses selected together process 80% of all finishing pigs slaughtered in the UK. Abattoirs were recruited to the study by BPEX and FSA organisations in Great Britain and Northern Ireland.

There was a consistently lower prevalence of bacteria (Salmonella and Yersinia) found on the carcase compared with carriage of the same microorganisms in the animal. This shows the effectiveness of the dressing procedures in the abattoir to limit the contamination of pig carcases and thereby control the risk of exposure of consumers to potentially harmful microorganisms.

• Salmonella: a total of 619 caeca, 624 carcase swabs and 625 rectal swabs, from 626 pigs, were tested for Salmonella. After accounting for clustering of pigs within farms, the prevalence of Salmonella in the caecal samples was 30.5% (95% CI 26.5-34.6) and the prevalence in the carcase swab samples was
  9.6% (95% CI 7.3-11.9).
• Toxoplasma: A total of 620 plasma samples, from 620 pigs, were tested for Toxoplasma. After accounting for clustering of pigs within farms, the seroprevalence of Toxoplasma was 7.4% (95% CI 5.3-9.5).
• Hepatitis E virus: A total of 640 plasma samples, from 640 pigs, were tested for Hepatitis E virus. After accounting for clustering of pigs within farms, the seroprevalence of Hepatitis E virus was 92.8% (95% CI 90.7-95.0). The prevalence of current infection, defined by the presence of detectable plasma HEV RNA,
  adjusting for clustering of pigs within farms, was 5.8% (95% CI 3.9-7.6).
• Yersinia spp.: A total of 624 carcase swabs and 620 tonsil samples, from 624 pigs, were tested for the presence of Yersinia. After accounting for clustering of pigs within farms, the prevalence of Yersinia was 32.9% (95% CI 28.8-37.0) for tonsil samples, and the prevalence in the carcase swab samples was 1.9% (95% CI 0.8-3.0).
• PRRS: A total of 621 plasma samples, from 621 pigs, were tested for antibodies to PRRSv. After accounting for clustering of pigs within farms the seroprevalence was 58.3% (95% CI 53.1-63.4). A total of 372 tonsil samples were tested for PRRS viral RNA. After accounting for clustering of pigs within farms, the prevalence of PRRSv RNA-positive tonsils in these 372 samples was 8.3% (95%CI 5.5-11.2).
• Antimicrobial Resistance in Campylobacter coli: Overall, 153 C. coli isolates were tested for their in vitro susceptibility to seven antimicrobials. The greatest levels of resistance were observed against tetracyclines (77.8%) and streptomycin (66.0%). There was also a moderate level of resistance against erythromycin (27.5%), nalidixic acid (17.0%) and ciprofloxacin (12.4%). No resistance was observed against either chloramphenicol or gentamicin.
• Extended Spectrum Beta Lactamase (ESBL) E. coli: A total of 637 caecal samples, from 637 pigs, were tested for ESBL E. coli. After accounting for clustering within farms the overall prevalence of ESBL E. coli was 23.4% (95% CI 19.2-27.6).