An outbreak of gastrointestinal illness in American tourists in May-June 2005 that was first thought to be foodborne has been linked to direct exposure to floodwater contaminated with raw sewage. On 1 June 2005, ORF (the Austrian Broadcasting Company) reported that 26 out of 36 American tourists who had eaten dinner in a well-known restaurant in Salzburg had fallen ill. According to the news report, 10 of the ill tourists had presented to a local hospital, triggering an outbreak investigaton by the local health authorities, who assumed salmonella to be the causative agent.

On November 9, 2004, a resident in a nursing home experienced a severe episode of vomiting in the dining room, in the presence of most of the other residents and members of staff. Following that episode, 17 of the 23 (73.9%) other residents and 7 of the 18 (38.9%) staff members fell ill with diarrhea and/or vomiting in the period up to November 17. A second cluster of gastroenteritis occurred between November 11 and 28, 2004, in a nearby hospital to which eight cases among the nursing home residents had been referred. Ten of 46 (21.7%) other hospital patients and 18 of 60 (30%) members of the hospital staff suffered from vomiting or diarrhea. Epidemiological and laboratory investigations proved a causal relationship between the two institutional clusters of short-lived gastroenteritis related by time and place, and identified Norovirus genotype GGII.4 (Jamboree-like) as the causative pathogen. Control measures for Norovirus, based on epidemiological and clinical features of the outbreak, were effectively implemented in the nursing home without waiting for virological confirmation. At the hospital, specific measures were not implemented until after virological confirmation of the causative agent, by which time 16 cases had already occurred. In a suspected Norovirus outbreak it is of great importance -- especially within closed and semiclosed settings -- to implement control measures as soon as possible, even before laboratory confirmation of the agent.

Norovirus is increasingly recognized as a leading cause of outbreaks of foodborne disease. We report on an outbreak in Austria that reached a total of 176 cases, affecting pupils and teachers from four schools on a skiing holiday in a youth hostel in the province of Salzburg in December 2007. A questionnaire was sent to the four schools in order to obtain data from persons attending the school trip on disease status, clinical onset, duration of illness and hospitalization. A cohort study was undertaken to identify the sources of infection. The school trip attendees were interviewed by questionnaire or face-to-face on their exposure to food items from the menu provided by the hostel owner. Of the 284 school holiday-makers, 176 fitted the definition of an outbreak case (attack rate 61.9%). A total of 264 persons on the ski holiday participated in the cohort study (response rate 93%). The day-by-day food-specific analyses did not find any food items served on any of five days (December 8-12) of the holiday to be associated with infection risk. The day-specific risk analyses revealed Monday December 10 (RR: 9.04; 95% CI: 6.02-13.6; P < 0.001) and Tuesday December 11 (RR: 3.37; 95% CI: 2.56-4.43; P < 0.001) as the two most risky days for having being exposed to norovirus. According to the epidemiological investigation, airborne transmission of norovirus originating from the first vomiting case most probably initiated this outbreak; foodborne genesis was excluded. During recent years, norovirus has become increasingly established as the most important causative agent of epidemic gastroenteritis in holiday-makers all over Europe. Tourism is one of the primary industries in Austria. Timely involvement of the relevant public health authorities is essential in any outbreak of norovirus gastroenteritis, irrespective of its genesis.

We report an outbreak of gastroenteritis due to Salmonella Enteritidis PT 21 associated with attending an annual traditional fair in a small Austrian village on 4 May 2005. The outbreak lasted from 4 to 8 May. Descriptive and analytical epidemiological investigations were conducted in order to determine the extent of the outbreak and to identify outbreak risk factors. Of the 115 persons who visited the fair, 85 persons fulfilled the criteria of an outbreak case (attack rate=73.9%). Stool specimens from 52 patients, including two kitchen staff, were tested for salmonella, and 20 specimens were positive for Salmonella Enteritidis PT 21. The cohort study revealed mixed salad (which included potatoes) as the likely cause of the outbreak (RR: 10.4, 95%CI 2.8 - 39.1; P=<0.001). The causative agent of the outbreak was cultured from the stock of eggs used at the fair and from all three drag swabs and one barn dust sample collected from the responsible egg laying flock. Molecular subtyping by pulsed-field gel electrophoresis of genomic DNA after XbaI digestion showed that isolates from eggs, from the flock and from humans were indistinguishable. We hypothesise that cross contamination from eggs to boiled potatoes occurred in the kitchen area, where raw eggs were handled by village residents preparing a traditional Viennese egg dressing. Unrefrigerated storage of peeled potatoes may have favoured bacterial growth. Eggs from small rural flocks of laying hens kept in a traditional 'natural' way should not be assumed to be salmonella-free.