A gastroenteritis outbreak investigation, NIGDE city center, March 2014

Abstract

Objective: In Nigde city center, during 18–30 March 2014, 1288 acute gastroenteritis cases were admitted to hospitals and family health centers. We investigated to identify the cause, mode of transmission, implement control measures, prevent future outbreaks. Methods: In case-control study to test the hypothesis “The source of this outbreak is contaminated tap water”, we reviewed health records for ICD-10 codes (A09, R11, K52) during 18–30 March. We defined probable case as onset of vomiting or diarrhea among 0-14 age-group resident of 15 neighborhoods with highest attack rates.. We compared 88 case-patients and randomly selected age-group-matched neighborhood controls. We tested clinical specimens, water samples. Results: Main symptoms of probable cases were diarrhea (80.7%), abdominal pain (84.1%), nausea (89.8%), vomiting (84.1%), fever (55.7%). When drinking only bottled water was taken as reference, drinking only tap water was 6.5 times higher in case patients (OR adj =6.5, 95%Cl=2.1–19.1). Of the 6 stool specimens, 4 tested positive for rotavirus. Water samples were positive for Escherichia coli, coliform bacteria. Free chlorine level was zero ppm in 5 of 7 samples. Conclusions: Contaminated tap water caused this rotavirus outbreak. The point of contamination couldn’t be identified. We recommended, drinking tap water chlorination, monitoring should be done regularly to prevent waterborne outbreaks. Key words : Water, Diarrhea, Case-Control Studies, Rotavirus, Outbreaks.