Revisiting the epidemiology of schistosomiasis and soil-transmitted helminthiasis in Chad: insights for improved...

Schistosomiasis (SCH) and soil-transmitted helminthiasis (STH) are endemic in Chad, particularly in areas with inadequate water, sanitation and hygiene (WASH) infrastructure. This study aimed to assess the prevalence and spatial distribution of SCH and STH among school-age children (SAC) to optimize mass drug administration (MDA) strategies.

A cross-sectional parasitological survey was conducted in 308 schools in 247 subdistricts across 25 health districts of seven provinces in Chad. Kato-Katz and urine filtration techniques were used to examine 15 828 SAC for Schistosoma haematobium, Schistosoma mansoni and STH. WASH conditions in schools and communities were also investigated.

The prevalence of S. haematobium was 2.28%, while S. mansoni was 0.74%, with significant geographical heterogeneity. STH infections were generally <5%, predominantly Ascaris lumbricoides. Based on World Health Organization treatment thresholds, two health districts now require annual praziquantel MDA, while one district (Korbol) has moved to the surveillance phase for SCH. WASH indicators showed gaps, with 73.27% of SAC not practice handwashing and 78.90% lacking access to safe drinking water.

Data generated from this survey filled the gaps for programmatic decisions and showed an overall low endemicity level of SCH and STH across the health districts surveyed. Improved WASH infrastructure and continued surveillance are critical for sustaining gains in morbidity control and elimination efforts.