Risk factors for sporadic Yersinia enterocolitica infections, Germany 2009-2010.

Yersinia enterocolitica is an important cause of acute gastrointestinal disease and post-infectious complications. In Germany, incidence of reported yersiniosis is relatively high compared with other countries of the European Union. Children aged <5 years are most frequently affected. The aim of our study was to identify risk factors for sporadic yersiniosis in Germany. A population-based case-control study was conducted in five federal states of Germany from April 2009 to June 2010. Cases exhibiting gastrointestinal symptoms were notified to the local health department with a Yersinia enterocolitica infection culture-confirmed from stool. Controls were selected from population registries and frequency-matched on age group and state of residency. Cases and controls received a questionnaire on possible risk factors by mail. Multivariable logistic regression modelling was used to identify risk factors and to calculate adjusted odds ratios (aORs). Population attributable fractions (PAFs) were estimated for exposures associated with yersiniosis. We analysed data on 571 case patients and 1798 controls. Consumption of raw minced pork, a dish frequently consumed even by young children in Germany, was the main risk factor for disease (aOR 4·7, 95% confidence interval (CI) 3·5-6·3, PAF 30%). This association varied by age group and, unexpectedly, was strongest for children aged <2 years (aOR 17·5, 95% CI 6·0-51·2). Other independent risk factors included recent preparation of minced pork in the household (aOR 1·4, 95% CI 1·1-1·9, PAF 21%), playing in a sandbox (aOR 1·7, 95% CI 1·3-2·4, PAF 17%), and contact with birds (aOR 1·7, 95% CI 1·1-2·6, PAF 4%). Prevention efforts should specifically target parents and caregivers of young children and focus on the high infection risk associated with consumption of raw minced pork.