Cholera Outbreak in some communities in North-East Nigeria: An unmatched case-control study

Abstract

Background Cholera, a diarrheal disease caused by the bacterium Vibrio cholerae, transmitted through fecal contamination of water or food remains an ever-present risk in many countries, especially where water supply, sanitation, food safety, and hygiene are inadequate. A cholera outbreak was reported in Bauchi State, North-eastern Nigeria. We investigated the outbreak to determine the extent and assess risk factors associated with the outbreak. Methods We conducted a descriptive analysis of suspected cholera cases to determine the fatality rate (CFR), attack rate (AR), and trends/patterns of the outbreak. We also conducted a 1:2 unmatched case-control study to assess risk factors amongst 110 confirmed cases and 220 uninfected individuals (controls). We defined a suspected case as any person > 5 years with acute watery diarrhea with/without vomiting; a confirmed case as any suspected case in which there was laboratory isolation of Vibrio cholerae O1 or O139 from the stool while a control as any uninfected individual with close contact (same household) with a confirmed case. Children under-5 not included in the case definition but samples from this age group were collected where such symptoms occur and line-listed separately. Data were collected with an interviewer-administered questionnaire and analyzed using Epi-info and Microsoft excel for frequencies, proportions, bivariate and multivariate analysis at a 95% confidence interval. Results A total of 9725 cases were line-listed with a CFR of 0.3% in the state. Dass LGA had the highest CFR (14.3%) while Bauchi LGA recorded the highest AR of 1,830 cases per 100,000 persons. Factors significantly associated with being a case were non-attendance at social gatherings (aOR = 0.65, 95% CI = 0.5–0.9) and source of water (aOR = 0.65, 95% CI = 0.5–0.8). Conclusion Non-attendance at social gatherings and provision of tap water were found to be protective against cholera infection. Public health actions taken included: chlorination of wells and distribution of water guard (1% chlorine solution) bottles to households including public education on cholera prevention messages amongst other actions.