July 2, 2014

It is contrary to the common belief that Campylobacter is a harmless commensal in chickens. Previously, infection of chickens had not been considered to cause disease and the bacteria were thought to be part of the normal microbiota in birds.

"The main implication is that Campylobacter is not always harmless to chickens. This rather changes our view of the biology of this nasty little bug," said Paul Wigley of Institute for Infection and Global Health at the University of Liverpool, an author on the study.

Campylobacter jejuni is the most frequent cause of foodborne bacterial gastroenteritis in the world, and chicken is the most common source of infections. Centres for Disease Control and Prevention estimate it affects approximately 1.3 million people per year in the US.

In the study, Wigley and his colleagues experimentally infected birds from four commercial broiler breeds. Though levels of the bacteria in the intestines did not differ by breed, immune response and inflammation did and one breed showed damage to the gut mucosa and developed diarrhea.

"Interestingly the breeds did not differ in the levels of bacteria we found in their intestines after infection, even when kept to normal slaughter age," said Wigley. "This suggests that chicken breed has little direct effect on the risk of Campylobacter entering the food chain but has a big effect on the health of the birds."

The most important finding of the study is that Campylobacter infection directly impacts broiler health and welfare.

Wigley commented, "On the positive side, we now know that chickens produce a robust immune response to infection, which in the longer term may allow us to develop vaccines,"