Outbreak of foodborne disease by Norwalk-like viruses genogroup II
Godoy, P.; Prat, A.; Alsedà, M.; Torres, J.; Domínguez, A.; Salleras, Lís.
Medicina Clinica 119(1): 13-15
2002
ISSN/ISBN: 0025-7753 PMID: 12062000 Document Number: 549278
Our goal was to investigate the epidemiological characteristics and etiology of an outbreak of food-borne disease caused by Norwalk-like viruses, genogroup II. We performed a historical cohort study on the consumption of 21 food items and clinical symptoms. We assessed RNA Norwalk-like viruses by RT- PCR in stool samples from 5 patients and 2 food-handlers. The potential involvement of each food item was assessed by relative risk at 95% confidence intervals (CI). The overall attack rate was 70.0% (7/10). The median incubation period was 35.0 hours. Symptoms included: vomits 85.7% (6/7), fever 85.7% (6/7) and diarrhoea 71.4% (5/7). Four food items were involved [fish (RR = 1.7; CI 95% 0.9-3.3); 'selection of cold meats' (RR = 1.6; CI 95% 0.9-2.7); yoghurt (RR = 1.5; CI 95% 1.0-2.4) and lamb (RR = 1.3; CI 95% 0.6-3.0)]. Three stool sample gave positive results for Norwalk-like viruses genogroup II. Important oversights in food-handlers' work were detected. RT-PCR enabled us to confirm the etiology of this outbreak as Norwalk-like viruses genogroup II. Although patients recovered quickly, the outbreak caused considerable public alarm.