“…Several surveys have indicated a seasonal variation in the prevalence of poultry flock colonization (41,57,76,110; D. G. Newell, E. Hartnett, M. Madsen, J. Engberg, T. Hald, A. Wedderkopp, and A. Engvall, presented at the 10th International Workshop on Campylobacter, Helicobacter, and Related Organisms, Baltimore, Md., 1999). There is generally a higher rate of infection in summer than in winter, and the timing of this peak also appears to vary with latitude.…”