Salmonella and campylobacter contamination of raw retail chickens from different producers: a six year survey

Abstract

Between 1995 and 2000, a prospective survey was undertaken to investigate the levels of contamination of raw retail chickens (n=1127) with salmonella and campylobacter. The levels of contamination over the 6-year period were 11% (95% CI±6·5%) for salmonella, and 57% (95% CI±9·5%) for campylobacter. S. Bredeney (20%) and S. Enteritidis (18%) were the dominant serovars. Although salmonella contamination was higher than in an earlier survey we conducted (7%), since 1998 it has declined to 6%. Many S. Enteritidis isolates (43%) were associated with one large integrated poultry organization that appears to have successfully managed the contamination, and the serovar has not been isolated since 1998. Contamination ranged from 0 to 44% between different producers. There was no significant difference between producers contributing large and small numbers of samples, although some small producers had much poorer contamination rates than others. S. Bareilly, S. Bredeney, S. Enteritidis and S. Virchow showed associations with particular producers. Campylobacter contamination remains high. Contamination ranged from 47 to 81% between different producers. This study did not show a temporal association between contamination of chickens and human campylobacter infections, indicating that many cases of human campylobacteriosis, particularly during seasonal peaks, do not originate from chickens. Control measures that have reduced salmonella contamination have been largely ineffective against campylobacter and new interventions are needed. Most raw chickens are contaminated with these pathogens, and communicating the importance of minimizing this risk to caterers and the public is vital in reducing human infections.