A Norovirus Outbreak in a Primary School, Hwalien County, 2010

In the morning on November 25(superscript th), 2010, the school nurse of School A reported 13 students were on sick leave. She noticed that most students including teachers in the class had vomiting and diarrhea. Thus, the local Bureau of Health, the Sixth Branch of Taiwan Centers for Disease Control (TCDC) and Eastern Regional Office of Taiwan Food and Drug Administration (TFDA) initiated epidemiologic investigation and identified six schools and institutes were involved in this outbreak. Strict measures including increase social distance, high frequency hand washing and environmental disinfection were implemented and the outbreak was blockaded at the second wave in all but the School A. Among the 62 human and 3 food specimens collected during the surveillance period, 10 stool specimens were tested positive for norovirus. According to the symptoms, the incubation period and test result of case-patients, this outbreak was regarded as a norovirus infection. Initially, this outbreak occurred in the primary school A with a common source and then subsequently transmitted into epidemiologically linked schools and institutes and led to small scale clustering. In addition to contact a patient and handling vomitus, our research indicated that the spatial distance to a case-patient with vomiting was positively correlated to the date of onset, it implied that invisible droplets might mediate contact infection, and reemphasized the importance of hand washing and high frequency environmental disinfection.