A 1-YEAR EPIDEMIOLOGIC-STUDY OF CAMPYLOBACTERS IN 18 SWEDISH CHICKEN FARMS

Broiler chickens are often intestinal carriers of Campylobacter. Durin g processing, Campylobacter may be spread over the carcass. Thus, unde rcooked chicken meat, or other foods contaminated by raw chicken can a ct as a source of infection to humans. This study was conducted to ide ntify risk factors for chicken flocks being colonized with Campylobact er. Eighteen chicken farms with altogether 62 chicken compartments wer e studied for 1 year with visits during each growing period and sampli ng of chicken caecal contents at slaughter. Four to six subsequent flo cks were raised in each compartment during the study. A detailed quest ionnaire was used to record farm parameters such as building materials , feed and water equipment, hygiene and management routines. Campyloba cter prevalence varied between farms, between growing periods within t he farms and also during the year, with lowest prevalence during the s pring. Campylobacters were isolated from 27% out of 287 flocks. Only t wo farms were negative at all samplings. Often the flock following a p ositive flock in a compartment was negative, indicating that normal cl eaning and disinfecting routines are sufficient for eliminating the ba cteria from the house. Usually only one serotype was found in each pos itive flock. Campylobacter occurrence increased with the age of the ch ickens at slaughter, and also with flock size. Univariable chi-square tests were done of the association between possible risk factors and C ampylobacter prevalence. Factors associated with higher Campylobacter prevalence in flocks were lack of or diffuse hygiene barriers, increas ing flock size, increasing age at slaughter, short vs. long empty peri ods, wet litter beds, other poultry nearby or staff handling other pou ltry, flocks divided before slaughter, staff loading to slaughter at s everal farms and occurrence of mice. Under Swedish conditions, water d oes not seem to be a source of infection for chickens. Origin and hand ling of day-old chickens, feed additives, houses and litter were not a ssociated with higher Campylobacter prevalence.