Childhood Diarrhoea in Urban Kenya: A Systematic Review (1995–2025)

Diarrhoea remains a leading cause of death among children under five (U5) in Kenya, where rapid urbanisation has created dense informal settlements in which poor sanitation, limited safe water, and poverty sustain high transmission rates. This systematic review, conducted in accordance with PRISMA 2020 guidelines, synthesises evidence on environmental, nutritional, socioeconomic, biological, and health system determinants of diarrhoea among children aged 0–59 months in urban Kenya. PubMed/MEDLINE, EMBASE, Global Health (CABI), the Cochrane Library, AJOL, and WHO IRIS were searched from January 1995 through December 2025, supplemented by grey literature. Quality was assessed using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias 2 framework. Thirty-two studies met the inclusion criteria. Pooled two-week prevalence was 21.4% (95% CI: 18.8–24.0%; 95% PI: 13.1–32.8%). Key determinants, listed in descending order of pooled effect size, were: open defecation (OR 2.87), household poverty (OR 2.50), absence of handwashing with soap (OR 2.31), non-exclusive breastfeeding (OR 2.18), stunting (OR 1.92), and low maternal education (OR 1.87). Publication bias was assessed using Egger’s test for outcomes with ≥10 contributing studies; no substantial asymmetry was detected. Evidence was heavily concentrated in Nairobi’s informal settlements. Childhood diarrhoea in urban Kenya is multi-determinant, with WASH deficits, undernutrition, and poverty as the predominant structural risk factors. Integrated multi-sectoral interventions and research expansion beyond Nairobi to secondary cities are urgently needed. This review is directly relevant to Sustainable Development Goal Targets 6.1 and 6.2. Note: This review was not prospectively registered in PROSPERO, which is acknowledged as a limitation.