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

ABSTRACT

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.