Estimating the time at which commercial broiler flocks in Great Britain become infected with Campylobacter: a Bayesian approach

Abstract

Campylobacter is a common cause of intestinal disease in humans and is often linked to the consumption of contaminated poultry meat. Despite considerable research on the topic there is a large amount of uncertainty associated with Campylobacter epidemiology. A Bayesian model framework was applied to multiple longitudinal datasets on Campylobacter infection in UK broiler flocks to estimate the time at which each flock was first infected with Campylobacter. The model results suggest that the day of first infection ranges from 10 to 45 days; however, over half had a time of infection between 30 and 35 days. When considering only those flocks which were thinned, 48% had an estimated day of infection within 2 days of the day of thinning, thus suggesting an association between thinning and Campylobacter infection. These results demonstrate how knowledge of the time of infection can be correlated to known events to identify potential risk factors for infection.

Fig. 1.

The median estimate for the time at which each of the 108 broiler flocks in the dataset first became infected with Campylobacter (t₀).

Fig. 2.

The difference between the day of first observed Campylobacter detection and the median estimated day of infection for each of the 108 UK broiler flocks (D_d).

Fig. 3.

The difference between the day on which UK broiler flocks were thinned and the median estimated day of Campylobacter infection (D_T).

Fig. 4.

The within-flock prevalence curve for a 28 500 bird flock in which Campylobacter infection is initiated on day 0 by a single bird, β = 1·78.