Cholera amid the climate crisis: a systematic review of flooding-driven health risks in West Africa

Flooding, a major climate-related disaster, poses a growing threat to public health in West Africa. Frequent and severe rainfall, coupled with poor infrastructure and weak sanitation systems, has worsened the spread of cholera and other waterborne diseases across the region. Despite the rising number of flood-related outbreaks, there remains limited systematic evidence on how such events influence cholera incidence in West Africa. This review aims to systematically synthesize evidence on how flooding, as a climate-induced event, influences cholera incidence and distribution, and to identify gaps in surveillance and health system responses across the countries in West Africa. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was conducted across electronic databases (PubMed, Wiley Online Library) and web-based platforms (Google, Google Scholar) which covered studies published up to May 2024. Search terms included “climate change,” “cholera,” “waterborne diseases,” “flooding,” and “West Africa.” Studies were eligible if they presented primary data and were conducted in a West African country. Unrelated studies were excluded to ensure data quality and comparability across sources. Screening, data extraction, and quality assessment were conducted independently by two reviewers. From 1,440 records identified, seven studies met the inclusion criteria after screening. The included studies consistently reported an association between climate variability and cholera incidence in West Africa. Increased rainfall, especially during seasonal transitions, was frequently associated with the onset of cholera outbreaks. Several studies indicated that El Niño events influenced the geographic distribution of cholera, increasing incidence in some areas while reducing it in others. Although flooding was a contributing factor in transmission, drought conditions were reported to exacerbate cholera outbreaks more severely in specific settings. Model projections suggested a continued rise in cholera incidence under future climate scenarios. This review highlights the influence of climatic variables including rainfall anomalies, temperature fluctuations, and interannual climate oscillations on cholera dynamics in West Africa. The findings emphasize the urgent need to incorporate climate data into public health planning, early warning systems, and cholera prevention strategies. In the face of intensifying climate change, developing climate-resilient health systems is essential to reducing cholera burden and safeguarding vulnerable populations in West Africa.