A foodborne outbreak due to norovirus in Austria, 2007.

A foodborne norovirus outbreak occurred after a pre-Christmas celebration among a group of local foresters in Austria in December 2007. A total of 66 persons, 60 participants of the Christmas party and 6 kitchen staff members of the restaurant where the party took place, were identified as the at-risk cohort. Questioning of this cohort was performed by self-report questionnaires or telephone interviews (response rate of 95%). The outbreak attack rate was 33.3% (21 of 63 persons), including two of the kitchen staff. Three stool specimens yielded norovirus genogroup II. Univariate analysis revealed that exposure to a ham roll and pastry was possibly associated with risk of gastroenteritis (risk ratio [RR] of 4.45, 95% CI of 1.91 to 10. RR of 2.44, 95% CI of 0.93 to 6.39). After controlling for the effects of sex, age, and other food items with a log-linear model, ham roll remained significantly associated with disease risk (RR of 3.91, 95% CI of 1.57 to 9.76). Ham roll was most likely contaminated with norovirus during preparation by a disease-free kitchen assistant, whose infant became sick with laboratory-confirmed norovirus gastroenteritis 2 days before the party. Informing food handlers about the possible risk of food contamination with norovirus and training them in the appropriate measures of hand hygiene and environmental disinfection at the working place and at home are essential for preventing food-related norovirus outbreaks. Norovirus-infected household members of healthy food handlers must be considered a possible reservoir for foodborne norovirus outbreaks.

Outbreak of acute gastroenteritis of unknown etiology caused by contaminated drinking water in a rural village in Austria, August 2006.

BACKGROUND: In August 2006 a physician from a rural village reported an outbreak of acute gastroenteritis. An investigation was undertaken in order to determine the magnitude of the outbreak, the source of infection and to prevent further disease. This is the first published outbreak of acute gastroenteritis caused by contaminated drinking water in Austria. METHODS: For descriptive epidemiology, the investigators had to rely on voluntary cooperation from physicians and patients, data collected by a police officer and data on sick leave reported by physicians to the health insurance system. RESULTS: Microbiological testing of water samples indicated that this cluster was caused by fecal contamination of untreated drinking water. Age and sex distributions were available for 146 of 160 cases: ages ranged from 5 to 91 years (median 45) and 81 cases (55.5%) were female. Stool samples from 14 patients were sent for microbiological analysis: all tested negative for Salmonella, Campylobacter, Shigella and Yersinia enterocolitica. Specimens were not tested for viruses, parasites or enteropathogenic Escherichia coli. DISCUSSION: In this outbreak no identification was made of pathogenic microorganisms in stool samples from affected patients, despite the occurrence of fecal indicator organisms in samples of drinking water. In outbreaks of gastroenteritis, medical practitioners should encourage microbiological testing beyond the limited routine program. Public health officers must be made aware that the spectrum of routine laboratory tests on stool specimens does not cover the wide array of pathogens capable of causing waterborne outbreaks. The springs serving the affected village originate in a mountainous area of karst formations, and heavy falls of rain that occurred at the beginning of the outbreak may explain introduction of fecal bacteria. In view of the unsolved problem of possible future contamination of springs in karst areas, the water department of this district authority has issued an order requesting installation of a permanent ultraviolet water-treatment facility.