Prevalence and sources of Campylobacter spp. contamination in free-range broiler production in Belgium

An one year epidemiological study was carried out between February 2005 and January 2006 in Belgium to assess the Campylobacter prevalence in free-range broiler production. Three successive broiler flocks on 6 belgian farms were investigated for the presence of Campylobacter ssp. during the rearing period. Each flock was visited four times, before and after the outdoor rearing period. During each visit, samples were taken in the broiler houses (litter, cecal droppings, water-lines, feed, entrance premises) as well as from the outer rearing environment (open-air range). Conventional microbiological methods combined with biochemical tests were used for the Campylobacter detection, species identification and isolation. Campylobacter prevalence was very high in free-range broiler production during the experimental period. C. jejuni is the main species isolated from all contaminated samples, while mixed C. jejuni/C. coli infections sometimes occured. Contamination of the broiler flocks was increased in summer/autumn, with a 100% flocks contamination, whereas only 4 (66.7%) and 3 (50%) of the flocks became Campylobacter positive in spring and winter respectively, at the end of the rearing period. Moreover, about 53.8% of contaminated flocks were infected with Campylobacter before chicks have access to the open-air range. In 69.2% of the Campylobacter-positive flocks, the open-air range soil belonged partly of fully to environmental samples found to be Campylobacter-positive before flock infection. The other potential sources of infection were delivery tray, entrance premises floor and water-lines. The access to an open-air range seems to be an important way of contamination of broilers because Campylobacter prevalence in the flocks increased after going out.