Remapping parasite landscapes: Nationwide prevalence, intensity and risk factors of schistosomiasis and...

Soil-transmitted helminthiasis (STH) and schistosomiasis (SCH) remain significant public health challenges in Rwanda, affecting individuals across all age groups. Despite ongoing mass drug administration (MDA) efforts, updated data on prevalence and risk factors are crucial for effective control and elimination strategies. This study reassessed the prevalence of STH and SCH in both children and adults in Rwanda, along with their associated risk factors, to guide control efforts.

A nationwide survey was conducted across 30 districts, testing 17,360 individuals for STH and 17,342 for Schistosoma mansoni using Kato-Katz (KK) and Point-Of-Care Circulating Cathodic Antigen (POC-CCA) tests. Mixed-effects logistic regression models were used to identify risk factors while accounting for district-level variability.

The overall prevalence of STH was 38.7% (95% CI: 37.9-39.4), highest among adults (46.1%, 95% CI: 44.8-47.3) and lowest among preschool-aged children (30.2%, 95% CI: 29.0-31.5). Species-specific prevalence was 27.0% for Ascaris lumbricoides (95% CI: 26.3-27.6), 11.6% for Trichuris trichiura (95% CI: 11.2-12.1), and 10.7% for hookworm (95% CI: 10.3-11.2). Moderate-to-heavy intensity (MHI) infections were detected in 8.1% of Ascaris lumbricoides (95% CI: 7.7-8.5), 0.8% of Trichuris trichiura (95% CI: 0.6-0.9), and 0.1% of hookworm (95% CI: 0-0.2). SCH prevalence was 1.7% (95% CI: 1.5-1.9) by KK and 27.2% (95% CI: 26.5-27.9) when trace results on POC-CCA were considered positive. Heavy Schistosoma mansoni infections were rare (0.1%, 95% CI: 0-0.1). Mixed-effects logistic regression (p < 0.05) showed that for STH, higher odds were associated with being single (AOR: 1.74), no education (AOR: 1.56), use of human excreta as manure (AOR: 1.43), unimproved water sources (AOR: 1.17), and proximity to marshlands (AOR: 1.17). Lower odds were seen among those with higher education (AOR: 0.55), unemployed (AOR: 0.34), self-employed or retired (AOR: 0.53), students (AOR: 0.54), those with deep toilets (AOR: 0.78), and those treating water consistently (AOR: 0.79). For SCH, higher odds were linked to being single (AOR: 1.61), no education (AOR: 1.41), proximity to lakes (AOR: 1.76) or rice fields (AOR: 1.31), use of treated (AOR: 1.32) or untreated (AOR: 1.60) excreta as manure, and living over an hour from a water source (AOR: 1.42).

STH and SCH remain significant public health challenges in Rwanda, with certain regions and population groups still exceeding the elimination threshold as public health problems. Expanding MDA programs to include adults, improving sanitation and hygiene, ensuring universal access to clean water, and promoting community education on safe practices are essential for achieving sustainable control and elimination of these infections.