Cholera remains a major global public health threat, with Sub-Saharan Africa (SSA) bearing a disproportionate burden of recurrent outbreaks and elevated mortality rates [1]. Countries including Malawi, Nigeria, Mozambique, Zambia, and the Democratic Republic of Congo continue to report substantial cholera morbidity, particularly in communities lacking sustained access to safe drinking water and adequate sanitation services [2–4]. Malawi’s 2022 epidemic, which resulted in more than 58,000 reported cases and 1,761 deaths, illustrates the severity of the ongoing cholera crisis and the limitations of reactive outbreak control strategies in the absence of long-term infrastructure investment [5, 6]. The persistence of large-scale outbreaks despite decades of global cholera control efforts highlights entrenched structural vulnerabilities across the regions [1].

Environmental pollution plays a central role in sustaining cholera transmission in SSA. Contaminated surface and groundwater sources, inadequate waste management systems, and poorly maintained sanitation infrastructure create ecological conditions that enable the environmental persistence of Vibrio cholerae [7, 8]. A global meta-analysis found high levels of V. cholerae in environmental samples, highlighting polluted water systems as important sources of ongoing transmission [9]. Across many SSA settings, rapid urbanisation and the expansion of informal settlements have outpaced infrastructural development, resulting in overcrowded environments where drainage systems, latrines, and waste disposal facilities are insufficient or entirely absent [10]. Seasonal flooding and extreme rainfall events further worsen these conditions by damaging sanitation facilities and dispersing faecal contamination into water sources used for domestic purposes [11].

Although cholera epidemiology and WASH-related interventions have been widely documented, the varying role of environmental pollution in driving recurrent and persistent outbreaks across SSA remains under-examined. While some reviews in Sub-Saharan Africa have explored environmental factors related to cholera transmission, much of the existing literature remains fragmented, with limited integration of environmental contamination, infrastructural decay, and socio-economic vulnerability within a single analytical framework [12]. This fragmented approach constrains the development of long-term, context-appropriate prevention strategies and reinforces reliance on emergency response mechanisms [3]. An integrative understanding of how environmental pollution interacts with structural determinants, including poverty, displacement, weak governance, and fragile infrastructure is essential in addressing a root cause of cholera transmission.

Communities most affected by cholera, experience multiple overlapping vulnerabilities. Refugee settlements, peri-urban informal communities, and fishing populations frequently lack reliable access to safe water and sanitation, increasing sustained exposure to contaminated environments [4, 13]. Limited access to healthcare, delayed treatment-seeking behaviour, and inadequate outbreak preparedness further heighten mortality risks during epidemics [6, 14].

This systematic review aims to examine how environmental pollution contributes to the recurrence and persistence of cholera outbreaks across Sub-Saharan Africa and to assess how public health and WASH-related interventions operate in high-risk and underserved settings. Specifically, it addresses the question of how environmental contamination, infrastructural conditions, and socio-economic vulnerability interact to influence cholera transmission dynamics. By integrating these environmental, infrastructural, and social dimensions, this review provides a structured synthesis of the pathways linking pollution, WASH deficiencies, and cholera risk. The findings are intended to inform sustainable prevention strategies, support evidence-based investments in water and sanitation infrastructure, and guide climate-resilient public health planning, with direct relevance to progress toward Sustainable Development Goals.

The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to ensure transparency, reproducibility, and methodological rigour [15]. The PECO framework (Population, Exposure, Comparison, Outcome) was applied to structure the review question and define eligibility criteria, particularly for observational study designs relevant to environmental and public health research [16] (Appendix, Table 1).

All records retrieved from database searches, grey literature, and manual searching were imported into Excel, and duplicate entries were removed prior to screening. Study selection followed a two-stage process consistent with PRISMA guidance, with two independent reviewers screening titles and abstracts, followed by full-text assessment of eligible articles. Disagreements at any stage were resolved through discussion, with a third reviewer consulted where consensus could not be achieved. The overall study selection and screening outcomes are summarised Fig. 1.

A standardized data extraction table was developed to ensure consistency and completeness. Data were extracted on author, year of publication, country, study design, population characteristics, environmental exposures, public health or WASH-related interventions, community-level socio-economic or health impacts, reported outcomes, and key findings (Appendix, Table 3).

Quality and risk of bias of included studies were assessed using tools appropriate to the study design (Appendix, Table 4). Observational studies, including cross-sectional, case-control, and cohort designs, were appraised using the National Institutes of Health (NIH) Quality Assessment Tool [20]. Each study was evaluated across key domains, including study design, exposure assessment, outcome measurement, and control of confounding, and classified as having low, moderate, or high risk of bias. Quality appraisal findings were used to inform interpretation of results but did not constitute exclusion criteria.

Nineteen studies published between 2015 and 2025 were included, representing several Sub-Saharan African countries: Uganda (n = 5), Zambia (n = 4), Ethiopia (n = 2), Mozambique (n = 2), Nigeria (n = 2) (Table 3). The included studies employed quantitative methodologies, including cross-sectional surveys, cohort studies, and outbreak surveillance designs. Sample sizes ranged from fewer than 100 confirmed cholera cases to studies involving more than 44,000 households.

Most studies were conducted in urban or peri-urban, low-income settings with limited access to safe water and sanitation. Extracted data were synthesized to assess links between environmental pollution and cholera outbreaks, and to evaluate the public health and socio‑economic impacts of relevant interventions.

An association between environmental pollution and increased cholera risk was reported across reviewed studies. Studies from Mozambique linked rainfall patterns to cholera outbreaks, as floods displaced latrine waste and contaminated shared water sources [21, 22]. In Ethiopia, Berhe et al. reported that over half of affected individuals lacked latrines, while two-thirds relied on contaminated water sources [23]. Similarly, Dongdem et al. documented faecal coliform levels exceeding WHO safety limits in Ghana [24]. Evidence from Kenya showed reductions in E. coli contamination following household‑level chlorination interventions [25].

This review examined how environmental pollution contributes to the recurrence and persistence of cholera outbreaks in Sub-Saharan Africa and how public health and WASH-related interventions perform in high-risk settings. The findings indicate that environmental pollution, particularly contamination of water sources, inadequate sanitation, and ineffective waste management, is a consistent and central factor shaping cholera transmission across diverse SSA contexts. These environmental risks are frequently intensified by flooding, poor drainage, and rapid, unplanned urbanization, reinforcing conditions that support sustained transmission rather than isolated outbreaks.

Across multiple countries, cholera incidence was repeatedly linked to faecal contamination of surface and groundwater, often following sanitation system failure during rainfall or flooding events [21, 23, 25]. The evidence suggests that pollution operates not merely as an episodic trigger but as a structural driver of cholera vulnerability, particularly where sanitation infrastructure is inadequate or poorly maintained. Importantly, nominal sanitation coverage often masked functional deficits. Studies from Uganda and Zambia demonstrated that unimproved or damaged latrine facilities, unregulated waste disposal, and ineffective drainage systems sustained environmental contamination even in communities reporting relatively high latrine access [31, 32].

Behavioral risk factors further shaped cholera transmission but were closely linked to environmental and infrastructural constraints. Poor hand hygiene, consumption of unwashed foods, and reliance on unsafe water sources were commonly reported across studies [28, 29]. However, these behaviors frequently reflected limited access to clean water, sanitation facilities, and safe food environments rather than lack of awareness. Evidence from Zambia and other settings showed that knowledge of cholera prevention did not consistently translate into safer practices where structural barriers persisted [30], highlighting the limitations of behavior-focused interventions implemented in isolation.

The review demonstrates that cholera disproportionately affects populations experiencing overlapping vulnerabilities, including poverty, displacement, and weak access to healthcare. Refugee settlements, peri-urban informal communities, and flood-affected populations consistently experienced higher outbreaks of intensity and mortality [13, 14, 22]. These findings indicate that environmental pollution interacts with socio-economic and health system constraints, compounding cholera risk and limiting the effectiveness of standard response measures.

Evaluation of interventions revealed variable effectiveness depending on context and integration. Emergency WASH measures and case-area targeted interventions reduced transmission during outbreaks, even in the absence of vaccination [26]. Oral cholera vaccines contributed to short-term control but were frequently constrained by access barriers, dose dropout, and limited duration of protection [21]. Across studies, interventions addressing a single component vaccination or hygiene promotion alone were insufficient where environmental contamination persisted.

Collectively, these findings indicate that sustained cholera control in Sub-Saharan Africa is more likely where integrated strategies address environmental pollution as a key determinant of transmission. Approaches combining vaccination, water treatment, sanitation infrastructure, surveillance, and community engagement were more consistently associated with improved outbreak control than isolated interventions. This evidence reinforces the Global Task Force on Cholera Control roadmap, emphasising multisectoral and environmentally grounded approaches aligned with long-term resilience rather than repeated emergency response.

Context‑sensitive interventions tailored to local ecological, social, and infrastructural conditions have the potential to reduce cholera risk. Recurrent outbreaks in communities exposed to unsafe water highlight the limits of vaccine‑only approaches and the need for durable structural improvements. Without addressing contaminated water sources, inadequate drainage, and poor sanitation, transmission persists despite emergency responses. Long‑term investment in essential infrastructure, alongside integration with urban planning, environmental health, and climate adaptation efforts, remains critical as climate‑related hazards such as flooding heighten vulnerability.

These findings should be interpreted considering contextual limitations. Some studies were observational, restricting causal inference. Heterogeneity in study design, outcome measures, and intervention definitions limited comparability across settings. Recall bias may have affected case–control studies, and disruptions related to conflict, displacement, and extreme weather events may have influenced data quality. Nonetheless, the consistency of patterns across countries and study designs strengthens confidence in the review that environmental contamination and inadequate WASH infrastructure remain central drivers of persistent cholera transmission in Sub‑Saharan Africa.

This review highlights the central role of environmental pollution in sustaining cholera transmission across Sub‑Saharan Africa, where inadequate sanitation, unsafe water, poor hygiene, and socio‑economic vulnerability remain persistent risk factors. Although vaccines and rapid response measures offer short‑term relief, long‑term control depends on addressing structural WASH deficiencies. The evidence supports integrated strategies that combine vaccination, sanitation improvements, household water treatment, behaviour change, and surveillance. To reduce recurrent outbreaks, policymakers must move beyond reactive interventions and prioritise sustained investment in drainage, waste management, and reliable water supplies, embedding cholera prevention within broader health, climate, and urban planning frameworks to strengthen long‑term resilience.