An updated assessment of the effect of control options to reduce Campylobacter concentrations in broiler caeca on human health risk in the European Union

Quantitative microbiological risk assessment (QMRA) studies have suggested that control options to reduce the concentration of Campylobacter spp. in broiler chicken caeca may be highly effective at reducing the risk of human campylobacteriosis. These QMRA studies have been updated based on scientific evidence obtained in the past decade. The relationship between Campylobacter concentrations in the caeca and on broiler skins after industrial processing was modelled by means of linear regression and combined with a number of consumer phase models (CPM) and dose-response (DR) models. The reduction of caecal Campylobacter concentration as reported for selected feed additives and vaccines, was used to estimate the relative risk reduction expressed as the percentage decrease in human campylobacteriosis cases in the EU associated with consumption of broiler meat. The model outputs suggest that the effectiveness of these control options are less pronounced than previously indicated. For example, the median estimate for the relative risk reduction obtained through a 2 log₁₀ reduction in caecal concentrations was 39% (95% CI 9–73%), whereas previous estimates were between 76 and 98%. The main reason for this finding is that recent studies show lower values for the slope of the regression line; the impact of using newly published DR models and CPMs is smaller. Still, the uncertainty associated to the estimated effects is large, mainly due to uncertainty about the slope of the regression line. Additionally, data on the effectiveness of vaccination and the application of feed and water additives obtained under field conditions are scarce, but they are a prerequisite to assess the risk reduction that may be achieved by these control options when applied in practice.