Risk factors for Campylobacter colonization in Danish broiler flocks, 2010 to 2011

The objectives of the two studies presented were to estimate the prevalence of Campylobacter-positive farms and flocks and to acquire updated knowledge about risk factors for the introduction of Campylobacter in Danish broiler flocks. In the first study, from September 2010 to September 2011, there were 25 Danish broiler farms visited, and a questionnaire was filled in by a veterinarian/consultant. In the second study, a similar questionnaire was distributed electronically to all Danish broiler farmers (n = 164) that were on record with an email address in the Quality Assurance System in the Danish Broiler Production (KIK) database. House-and flock-specific data collected in the surveys were supplemented with information obtained from the KIK database. Data obtained from the two studies were analyzed separately by logistic regression analysis. In both models, the dependent variable was Campylobacter flock status (positive/negative),which was based on real-time PCR testing of fecal material from the floor of each broiler house that had been collected preslaughter using a pair of tube gauze socks. This material was pooled into one sample. Of the 25 farms visited, 17 had delivered Campylobacter-positive flocks during the study period, and eight farms had no Campylobacter-positive flocks. Moreover, the flock prevalence of Campylobacter was 17% (n = 418). Data obtained from the electronically distributed survey revealed that 63% (n = 71) of the farms were Campylobacter-positive. Further, the flock prevalence of Campylobacter was 14% (n = 1,286). The multivariable models from the two sets of data identified the following statistically significant risk factors: summer vs. winter; if the previous flock in the house was positive for Campylobacter vs. if the previous flock in the house was negative; and litter delivered into the house close to the time of arrival of new chickens vs. storing litter on the farm. Furthermore, the data showed that a vertically based ventilation system (where most of the air is taken into the house through chimneys) constituted a higher risk than a horizontally based system (where the air is taken in through openings in the side walls).