Risk factors for Campylobacter infection in Danish broiler chickens.

Data from the Quality Assurance System in Danish Broiler Production (KIK system) were analyzed to identify within farm biosecurity- and management-related risk factors for Campylobacter infection in Danish broiler flocks. In the study, data from 2,835 flocks originating from 187 farms in the time period of December 2009 to November 2010 were included. The PCR test results of fecal samples collected on socks revealed that 14% of the Danish broiler flocks were positive to Campylobacter during the study period. Of the positive flocks, 55% were positive during summer time and the positive flocks during summer time were related to areas where clustering of infected farms was identified in previous conducted studies. The median number of people working in or entering broiler houses was 2 (from 1 to 7). The median slaughter age of Danish broiler flocks was 35 d (from 31-61 d). A multivariable logistic regression model with a random effect of farm was performed. The analysis revealed that flocks had a higher risk of acquiring positive infection status during summer time: odds ratio = 12.59 (95% CI: 6.79-23.36) and when more than one person entered the broiler house: odds ratio = 2.03 (95% CI: 1.19-3.84). Furthermore, there was a higher risk of a positive infection status if the test result of the farm for the previous flock was positive: odds ratio = 1.80 (95% CI: 1.22-2.63), if the broiler houses were built before and during 1990: odds ratio = 1.60 (95% CI: 1.17-2.18), and if the average slaughter age of the birds was more than 35 d: odds ratio = 1.33 (95% CI: 1.02-1.76).