ABSTRACT
BACKGROUND: We describe the investigation of an acute gastroenteritis outbreak with an explosive beginning, probably waterborne, that occurred in an nursing home in Albacete, in November 1999 and affected 104 inmates and 35 employees. The dominant symptoms were diarrhea and vomiting. METHODS: A case-control study was designed. We carried out a descriptive analysis of facts and crossing of variables with the help of simple tables. A multivariant analysis, by models of logistic regression, was conducted both for the explosive phase and for that of transmission person-to-person. RESULTS: The attack rate for inmates was 45.8% and for employees, 33.7%. An association was found between the use of the main dining-room of the nursing home and the explosive beginning of the outbreak and between the previous presence of a case-patient in the shared bedrooms and the person-to-person transmission. Norwalk-like virus was isolated from faeces samples of four cases. CONCLUSIONS: The analysis of the clinical and epidemiological findings as well as the laboratory results proved the implication of a Norwalk-like virus in this outbreak.
