Investigation of Norovirus Outbreak in Sattahip District, Chonburi Province, Thailand, August-September 2014

Abstract

A Norovirus outbreak occurred in residents of Sattahip subdistrict, Sattahip district, Chonburi province, Thailand during August - September 2014. Patients developed gastrointestinal symptoms, mainly nausea/vomiting (80.32%), followed by abdominal pain (50.00%), diarrhea (29.51%) and fever (8.36%). A total of 742 patients including sought care at 3 governmental hospitals (i.e., Queen Sirikitte Hospital, Apha Kon Kiattiwong Hospital and Sattahip K.M. 10 Hospital). Of those, 60.51% (449/742) were students and remaining 293 cases (39.49%) were general population. Common age-group was 10 - 14 years old who were school students in Sattahip subdistrict. Lab investigation revealed Norovirus by RT-PCR in 4 of 5 stool samples collected from patients. A case-control study identified an association between ice consumption and food poisoning (OR = 5.77, 95%CI = 3.08 - 10.88). This finding is compatible with detection of Norovirus in 5/9 samples of raw water collected from ice factory. Outbreak control measures included legal enforcement and policy advocacy by implementing coordinating mechanism among local administration organizations, district governor, royal Thai Navy and local public health authorities to shut down the implicated ice factory. Cleaning-up and improving raw water quality, sanitation of the ice factory was thoroughly carried out to meet Good Manufacturing Practice (GMP) standard. Ice trucks were disinfected by water with concentrated chlorine. Municipality emphasized on health education and market cleaning, ensured adequate concentration of residual chorine (> 1.5 ppm.) at the municipal water treatment plant and monitoring water quality by measuring residual chorine at schools. Recommendation to prevent food poisoning in school and creating a network of outbreak notification was given. Surveillance for food quality according to FDA standard and new patients who meet the case definition both in schools and hospitals was strengthened. As the results of combined interventions by multiple stakeholders, the outbreak was curtailed within 2 weeks.