Risk factors for Campylobacter spp. colonization in French free-range broiler-chicken flocks at the end of the indoor rearing period

The aim of this cross-sectional survey was to identify risk factors for Campylobacter spp. colonization in French free-range broiler flocks at the end of the indoor rearing period (between 35 and 42 days old). Seventy-three broiler farms were studied from March 2003 to March 2004 in France. A questionnaire was administered to the farmers and samples of fresh droppings were taken to assess the flocks’ Campylobacter status by bacteriology. Campylobacter species were determined by PCR. A logistic regression analysis was used to assess the influence of various factors on flocks’ Campylobacter status. 71.2% of the sampled flocks excreted Campylobacter spp. before going out on the range. The risk of a flock being colonized with Campylobacter was increased in the spring/summer period (RR = 1.8, p = 0.02) and autumn (RR = 2.2, p = 0.02) compared to winter, on total freedom rearing farms (RR = 3.3, p = 0.04) in comparison with farms with a fenced run, when the first disinfection of the poultry-house was performed by the farmer (RR = 2.4, p = 0.04) instead of a hygiene specialist, when rodent control was carried out by a contractor (RR = 1.8, p < 0.01) and not by the farmer and when the farmer came into the house twice a day as opposed to three time a day or more (RR = 1.5, p = 0.02). Use of a specific gate for chick placement decreased the risk of a flock being colonized with Campylobacter (RR = 0.5, p = 0.01) in comparison with using the gate for manual disposure or the door of the change room.