Trends of cholera epidemics and associated mortality factors in Cameroon: 2018-2023: a cross-sectional study

Abstract

Background: Cameroon has faced frequent and severe cholera outbreaks since 1971, with case-fatality rates (CFRs) ranging from 12% in 1991, to 5.3% in 2014, all higher than the less than 1% cholera CFR target set by WHO. However, not many studies providing insight on context-specific risk factors have been published. The purpose of this study was to describe the recent cholera outbreaks in Cameroon and to determine factors associated with mortality.

Methods: This was an analytical cross-sectional study that employed a retrospective design exploiting Ministry of Public Health cholera line-lists from 2018-2023. These line lists were obtained from the Public Health Emergency Operations Coordination and Control Center, compiled into a single Microsoft Excel Sheet, cleaned and analyzed using Microsoft Excel 2016 and SPSS version 20. Cholera cases were defined as those confirmed in reference laboratories via stool culture and suspected cases with proven epidemiological link to laboratory-confirmed cases (suspected cases in health districts with active laboratory-confirmed cases). Factors associated with cholera mortality were identified using binary logistic regression (adjusted odds ratios), after socio-demographic, clinical, and geographical distribution of cholera cases were described. Maps were generated using QGIS version 3.28.14.

Results: Between May 2018 and March 2023, Cameroon experienced four cholera epidemics resulting in 18,986 reported cases and affecting 8 out of 10 administrative regions. The three coastal regions (Littoral, South and South-West Region) reported 83.4% (15,839/18,986) of all the cases while the remaining five affected regions jointly reported 16.6% (3,147/18,986) cases. The most represented age group were those aged 25-35 years (21.9%; 4,163/1,876) and the male: female sex ratio was 1.27. The overall CFR was 2.7% (478 deaths/17,967 cases with known outcome) and was highest among persons > 65 years (6.8%; 59/869). Urban areas notified more cases than rural areas (13,267 vs 5,484). Factors associated with increased mortality were male sex (aOR 1.61, 95% CI: 1.30-2.04), dry season (aOR 1.67, 95% CI: 1.28-2.22), age above 45 years (aOR 1.79, 95% CI: 1.45-2.22) and severe dehydration at consultation (aOR 12.76, 95% CI: 7.66-21.25).

Conclusions: Cholera outbreaks occurred in eight out of the ten administrative regions in Cameroon during the study period and mortality appeared to be driven by multiple factors notably severe dehydration at time of consultation, advanced age, male sex and the dry season. The high caseloads and case-fatality rates reiterate the need for further strengthening of existing cholera surveillance and outbreak response mechanisms.

Keywords: Associated factors; Cholera; Epidemiology; Mortality.