An evaluation of sampling- and culturing methods in the Norwegian action plan against Campylobacter in broilers

The Norwegian Action Plan against Campylobacter in broilers was implemented in May 2001 with the objective of reducing human exposure to Campylobacter through Norwegian broilers. From each flock, samples collected at the farm about one week prior to slaughter, and then again at the slaughter plant, are examined for the presence of Campylobacter. All farmers with positive flocks are followed up with bio-security advice. Sampling of broiler products at retail level is also included in the Action Plan. The aim of this study was to evaluate the existing sampling and culturing methods of the Norwegian Action Plan against Campylobacter in broilers. The material collected was pooled faecal samples, pooled cloacae samples and caecae samples from individuals. The highest number of positives, from culturing of the pooled faecal samples, the pooled cloacae swabs and the caecae swabs from individuals, were obtained at incubation temperature 41.5 degrees C. When comparing the results at incubation temperature 37 and 41.5 degrees C, the faecal samples from the farms demonstrated a high concordance, with a kappa value of 0.88. The results from culturing cloacae swabs and caecae samples from slaughter plant level at two temperatures did not agree very well with a kappa value of 0.21 and moderate value of 0.57, respectively, but were both disconcordant at a level of 0.05. Modelling farm level data indicated that if increasing the number of pooled samples per flock from two (in existing regime) to three, the flock sensitivity increases from 89% to 95%. Modelling of slaughter plant data indicated that three pooled cloacae swabs are needed to identify 90% of the positive flocks. The results from the modelling of caecae data indicated that samples from seven individuals are sufficient to identify 90% of the positive flocks and caecae samples could thus be an alternative to cloacae sampling at slaughter plant level.