In Switzerland, 7,000-8,000 people fall ill with a Campylobacter infection annually. An increase of campylobacteriosis case numbers is being observed throughout Europe. Human cases of campylobacteriosis must be reported to the relevant authorities in Switzerland.

In Switzerland, an unusual increase in campylobacteriosis case numbers can be observed in the period around Christmas and New Year. Therefore, the Swiss Federal Office of Public Health, in agreement with the Swiss Federal Food Safety and Veterinary Office has commissioned Swiss TPH to perform a case control study in order to investigate this increase over the festive season.

“We are relying on data subject to reporting and telephone interviews with affected persons for this”, study leader Daniel Mäusezahl of Swiss TPH says.

The researchers interviewed affected persons who had fallen ill with a campylobacter infection between December 2012 and February 2013. An independent laboratory examination had confirmed a campylobacter infection in all interviewed persons. The focus of the interviews was on risk factors, the consultation of a doctor and the course of the illness experienced by the affected persons.

The study identified two factors for an increased risk of infection with Campylobacter pathogens. The risk of infection increased by a factor of four when consuming Fondue chinoise. About half of the notified campylobacteriosis cases over the Christmas and New Year period can be attributed to this source of infection.

The study also shows that the risk of infection can be decreased by hygienic measures at the table. As soon as the meat fondue consumers used compartmented or separate plates for raw and cooked meat, the risk of an infection decreased by a factor of up to five. Likewise, the risk of an infection decreased when consuming meat that had been previously frozen. “Campylobacter infections among consumers could be avoided to a large extent by employing the appropriate hygiene behaviour measures”, Daniel Mäusezahl says.

Philipp J. Bless, Claudia Schmutz, Kathrin Suter, Marianne Jost, Jan Hattendorf, Mirjam Mäusezahl-Feuz, Daniel Mäusezahl. A tradition and an epidemic: Determinants of the campylobacteriosis winter peak in Switzerland. European Journal of Epidemiology, DOI: 10.1007/s10654-014-9917-0