Hydro-Climatic and Environmental Influences on Population Vulnerability to Typhoid Fever in Lagoon Communities of Douala IV Municipality, Cameroon

Low-lying lagoon settlements may experience flooding, impaired drainage and faecal contamination of domestic water sources, but these mechanisms are not equivalent to demonstrated typhoid transmission. This observational study describes monthly climatic conditions, four related typhoid-report series and environmental exposure indicators in six communities of Douala IV Municipality, Cameroon. The available records comprise monthly rainfall and temperature for 2025, field-survey reports, health-centre records, laboratory-labelled reports, and summary information for 180 households. Monthly reporting series were compared using descriptive statistics and exploratory Pearson correlations; an ordinary least-squares model and a study-specific equal-weight normalised index were also assessed. Rainfall rose from 30 mm in December to 742 mm in August. The field, health-centre and laboratory series contained 4,138, 5,532 and 4,716 annual records, respectively. Their arithmetic sum (14,386) was not established as a count of distinct patients because record overlap could not be assessed. The monthly sum peaked in April (1,715) and reached its minimum in August (868). Rainfall was not significantly correlated with the monthly sum (r = −0.430, p = .163); the temperature association was also non-significant (r = .474, p = .119). A two-predictor model explained 22.5% of its variation (R² = .225, p = .317). Among households, 72.2% reported frequent flooding, 52.8% poor drainage and 61.1% use of open or closed wells. Faecal-coliform positivity was reported in 56.45% of tested water samples, although test counts and protocols were unavailable. A descriptive composite index averaged 0.396; it is not an independently validated infection-risk measure. These findings document substantial environmental exposure potential and differences among surveillance sources, but cannot establish population incidence or causal climatic effects.