Surveillance and infection tracing through molecular typing of Campylobacter from broilers

Campylobacter is an intestinal bacterium that occurs in many animal species. It infects humans through food, primarily chicken meat, but also via contaminated water and direct contact with animals. Infection with Campylobacter occurs worldwide, and it is the most common bacterial cause of gastrointestinal disease in humans in Sweden. Several species exist, but Campylobacter (C.) jejuni and C. coli are the most common, and they are also the ones most frequently associated with human infection.

The industry organization Svensk Fågel has, since 1991, coordinated a monitoring program for Campylobacter in chickens, mainly funded by the Swedish Board of Agriculture. The aim of the program is to achieve a low prevalence of Campylobacter in chicken flocks. Within the monitoring program, samples are taken from the ceca of chickens at slaughter. These samples are analyzed at the Swedish Veterinary Agency (SVA) for the presence of Campylobacter.

The prevalence of Campylobacter in broiler chickens increases during the warmer months of the year, which corresponds well with the number of domestically acquired Campylobacter infections in humans. In 2017, a collaboration was initiated between the Public Health Agency of Sweden (FOHM) and SVA (and periodically the Swedish Food Agency). The purpose was to analyze Campylobacter from patients and broiler chickens in parallel during selected weeks in winter and summer, and to compare the results. These parallel analyses ended in 2021, but SVA has since continued analyzing Campylobacter from broiler chickens. The analyses include both genetic characterization of the bacteria into so-called sequence types, and more in-depth comparisons of the entire genetic material. The results make it possible, for example, to trace potential transmission between producers and to implement measures to reduce the risk of spread.