An investigation of an outbreak of gastroenteritis in the Tavsanli District of Kutahya Province, July 2014, a Case-Control Study

<p><strong>Objective:</strong> On 18.06.2014 health authorities of the Tavsanli district reported 684 gastroenteritis patients; of whom 28 were hospitalized. We investigated this outbreak to identify the cause, mode of transmission and to implement control measures. <strong>Method:</strong> In this case-control investigation, we evaluated 154 probable cases defined as onset of vomiting or diarrhea (≥3/day), which were randomly selected from the 5 neighborhoods with highest attack rates. These were diagnosed as A09, R11, K52 ICD-10 codes between the 7th and the-30th June; and their age-groups were matched 1:1 with neighborhood-controls. Clinical and tap water samples were collected. <strong>Results:</strong> The attack rate was 3.3% and cases were widespread in the district. Main symptoms were nausea (88.9%), diarrhea (88.2%), abdominal pain (82.8%), and vomiting (71.8%). The symptoms started to increase 6 days after a flood, and the epidemic curve revealed a high peak. 66.9% of cases (103/154) had drunk from a neighborhood water fountain, compared with 37% (57/154) of the controls (ORMH=4.3, 95% CI=2.2-8.6); 18% (28/156) of cases compared with 27% (43/95) of the controls used bottled water (ORMH=0.5, 95% CI=0.3-0.9). Norovirus was detected in five stool specimens. Environmental investigation showed that there were 35 untreated neighborhood fountains and that the water tanks that providing water to neighborhood fountains was full of flood water. Norovirus was not identified in the water samples. <strong>Conclusion:</strong> The findings of the study reveal that this norovirus outbreak was likely due to drinking contaminated water from neighborhood fountains after the flood due to an unprotected neighborhood storage tank next to a canal, supplying the fountains.</p><strong>Keywords:</strong> Norovirus, matched case-control study, water, diarrhe