Cholera outbreak associated with drinking contaminated river water in Panyimur and Parombo sub-counties: Nebbi district, Uganda, March 2017

Introduction: On 10thFebruary 2017, Uganda Ministry of Health was notified of a suspected cholera outbreak in Nebbi district. The district experienced numerous cholera outbreaks with the latest in 2016. We investigated to determine the scope, mode of transmission, and exposures. Methods: We defined a suspected case as sudden onset of acute watery diarrhoea in a resident (>5 years) from Parombo or Panyimur subcounties in Nebbi district, during 1 January-9 March 2017. A confirmed case was a suspected case with culture-confirmed Vibrio cholerae from stool. We conducted descriptive epidemiology of case-persons to inform hypothesis generation and a case-control study involving 67 case-persons and 134 control-persons to test the hypothesis. Results: We identified 222 suspected case-persons; samples from two yielded Vibrio cholerae O139. Three case-persons died (CFR=1.4%). The epidemic curve indicated a point-source outbreak. Among 67 cases, 40 (60%) drank river water, compared with 56 (42%) of 134 controls (OR 2.2, 95% CI: 1.2- 4.1). Visual assessment revealed that river water had high turbidity and we observed mass open defecation. Conclusion: This outbreak affected two sub-counties and was associated with drinking contaminated river water. We recommended treating drinking water by the community members and health education on drinking water safety and proper waste disposal in the communities. And for long term, the district water department should increase the number and functionality of boreholes or piped water in the communities.