BACKGROUND: On May 25, 2016, the San Diego County Epidemiology Program was notified of an outbreak of acute gastroenteritis at an elementary school. At least 60 students and 14 teachers were reported to be ill. Symptoms included vomiting and nausea. Duration of symptoms was unknown and diarrhea was not reported – suspected etiology was initially unclear. Food-borne transmission was not suspected. On May 26, additional students were reported with symptoms of diarrhea, nausea, and vomiting.
METHODS: Recommendations based on the California Department of Public Health guidance for prevention and controls of acute viral gastroenteritis outbreaks were provided. Specimen testing at the San Diego County Public Health Laboratory was performed. An online survey was developed for parents to report ill students, identify risk factors for infection, and to encourage stool specimen submission. A case was defined as a student or staff member who reported vomiting and/or diarrhea onset between May 17 and June 8, 2016. An epidemiologic curve was created based on absenteeism data, online survey results, and ill teacher interviews.
RESULTS: Of 760 students at the school, 74 (10%) were identified as cases. The estimated median age among students was 7 years (range: 5-12 years). Symptoms included vomiting (95%) and diarrhea (57%), with median illness duration of 13.6 hours (range: 1-96 hours). Specimens (2 vomitus and 2 stools) were tested for norovirus by real-time reverse transcription-polymerase chain reaction. Two specimens (1 vomitus and 1 stool) tested positive for norovirus genogroup I. Descriptive analysis showed that grade levels with the highest proportion of cases were the sixth (30%) and fifth (18%) grades. The grade level with the lowest proportion of cases was seventh grade (5.4%).
CONCLUSIONS: On May 23, a 5th grade student was reported to have vomited in the art classroom. Students from all grades (K-6) were rotated through the art classroom throughout the day. Additionally, 50% of teachers who were interviewed commented that illness among students and staff was likely due to contaminated environmental surfaces in the art classroom. Illness among students and staff decreased significantly after the school closed for 2 days and implemented appropriate control, prevention, and environmental disinfection measures.