A case-control investigation on Norovirus aggregation in school

ObjectiveTo investigate and analyze the cause of an outbreak caused by Norovirus which happened at a middle school in Shanghai.

MethodsCase-control investigation method was used.Patients with gastroenteritis symptoms were defined as case group, and those without symptoms in the same class as control group.Retrospectives epidemiological investigation had been applied.Biological specimens of cases were tested in laboratory.

ResultsThere were a total of 19 students with vomit and(or) diarrhea symptoms.Case-control study showed that the risk factor might be one kind of homemade food sold from the stalls at the scenic spot (P=0.001), Norwalk virus RNA(type GⅡ) were detected from stool specimens of 7 patients.

ConclusionThe outbreak was probably caused by Norovirus, and the suspicious risk factor was contamination of homemade food from stalls at the scenic spot.