[Outbreak of food-borne Norovirus associated with the consumption of sandwiches]. / Toxiinfección alimentaria por Norovirus debida al consumo de bocadillos.

BACKGROUND AND OBJECTIVE: The aim of this study was to conduct an investigation into an outbreak of food-borne disease at a hotel, when epidemiological and microbiological results determined that the etiological agent was Norovirus and the source of infection was food handlers. PATIENTS AND METHOD: We detected an outbreak of gastroenteritis in a group of 59 students and teachers from a secondary school who were staying at a hotel in Espot, Lleida (Spain). A historic cohort study was conducted into the consumption of water and food and clinical symptoms were also analyzed. We studied the water supply and various food items. Faecal specimens from 14 patients and four food handlers were cultured and examined for Norovirus by PCR-RT. The influence of each foodstuff was assessed by relative risk (RR) at 95% confidence intervals. RESULTS: We interviewed 96.6% of the patients (57/59). The overall attack rate was 66.7% (38/57). The median period of incubation was 25.0 hours (maxim 59 and minimum 19 hours). Symptoms included abdominal pain 94.7% (36/38), vomiting 86.8% (33/38), nausea 76.3% (29/38), diarrhoea 52.6% (20/38) and fever 48.6% (17/35). Of the four different kinds of drinking water and 13 food items studied, the only significant factor was the consumption of sandwiches (RR = 2.3; CI 95%, 1.1-5.1). Cultures were negative for bacteria. PCR-RT tests were positive for Norovirus in 12 of 14 faecal samples. There were also positive results for the same virus in two of four faecal samples from food handlers, although neither of them presented clinical symptoms. CONCLUSIONS: This research highlights the fact that food-handlers should always be investigated in the case of outbreaks of food borne Norovirus. They must strictly follow hygiene rules, especially when they produce food that is to be eaten without any form of cooking.

[Waterborne outbreak of Shigella sonnei caused by consumption of public supply water]. / Brote de gastroenteritis por el consumo de agua de suministro público causado por Shigella sonnei.

OBJECTIVE: To investigate a waterborne outbreak in the population of València d'Àneu (Lleida, Spain). METHODS: A cohort study of consumption of mains water, bottled water and spring water was carried out. The sample was obtained by telephone contact with all private numbers in the municipality. We surveyed 58.3% of the population census (105/180) for water consumption, number of glasses drunk daily and symptoms. The water supply in the municipal system was sampled, and the presence of Enterobacteriaceae in the stool samples of 10 patients was determined. The association of each type of water was studied with estimation of relative risks (RR) and 95% confidence intervals (95% CI). RESULTS: The overall attack rate was 64.8% (68/105). The epidemic curve was consistent with an exposure of 6 days. Consumption of public supply water was associated with gastroenteritis (RR=4.2, 95% CI: 1.5-11.9). In addition, a dose-response relationship was found (χ(2)=34.1; p <0.001). There was a higher risk of illness in consumers of 2-3 glasses per day (RR=4.3; CI 95%: 1.9-9.9) and in those drinking more than three glasses per day (RR=4.9; 95% CI: 2.2 -10.9). The chlorinator of mains water froze and stopped working. Six stool cultures were positive for Shigella sonnei. CONCLUSIONS: A waterborne outbreak of S. sonnei was caused by contamination of the public water supply. Investigation of illegal dumping of wastewater was recommended. Municipalities should ensure proper disinfection systems and prevent spillage near deposits.