Representing uncertainty in land surface hydrology: fully coupled simulations with the ECMWF land surface scheme

A case-control study was conducted in 2005 to identify risk factors for the presence of Campylobacter spp. in Norwegian broiler flocks. A total of 131 broiler farms (44 cases and 87 controls) were included in the study, and 1 flock from each farm was included in the statistical analyses. Data on farm and flock level were collected by means of a questionnaire designed for the present study. The relationship and strength of association between the presence of Campylobacter spp. in the broiler flocks and several factors were investigated by unconditional logistic regression. The following factors were found to be associated with an increased risk of testing positive for Campylobacter spp.: water from a private water source, swine holdings closer than 2 km, a specific slaughterhouse, a hired animal caretaker, transport personnel passing through the hygiene barrier when delivering day-old chickens, less than 9 d between depopulation and restocking, and multiple broiler houses on the farm.