The seasonality of human campylobacter infections and Campylobacter isolates from fresh retail chicken in Wales.

Seasonal peaks in human Campylobacter infections and poultry isolates have been observed in several European countries but remain unexplained. This study compared data on human infections and isolation rates from fresh retail chicken portions purchased in Wales between January and December 2002. Overall, 71% of chicken samples were positive for Campylobacter, with rates in excess of 90% in week 24. Human isolates (2631) peaked between weeks 22 and 25 and chicken isolates (364) between weeks 24 and 26. The authors postulate that the seasonal rise in human infections is not caused by a rise in poultry isolation rates, but that both are more likely to be associated with a common, but as yet unidentified environmental source. Epidemiology and Infection 2005;133:49-52.