Hidden in the Dirt: The Persistent Presence and Environmental Drivers of Soil-Transmitted Helminths in parts of Ogun State, Southwestern Nigeria

Introduction: Soil-transmitted helminths (STHs) remain a significant public health challenge in Nigeria, particularly in areas with inadequate sanitation and environmental conditions that favor parasite persistence. This study investigated the prevalence of STHs in soil samples from three Local Government Areas in Ogun State, Nigeria, and evaluated the influence of selected soil physicochemical parameters on helminth occurrence.

Methods: One hundred and sixty-four (164) soil samples were collected from public locations, including dumpsites, markets, schools and roadsides, across 35 communities. In situ measurements of soil temperature, pH and moisture were obtained using a soil survey probe inserted vertically to a depth of approximately 5 cm. Parasitological examination of soil samples was performed using the sedimentation technique. Data analysis was conducted using R software. Descriptive statistics were used to summarize parasite distribution, while inferential statistics were applied to assess associations between STH occurrence and environmental variables, with statistical significance set at p < 0.05.

Results: Results revealed that out of the 164 samples, 152 (92.7%) were contaminated with at least one parasite species. The most frequently detected helminths were Taenia spp. (76%) and Ascaris lumbricoides (61%), followed by Trichuris trichiura (12%), Hookworms (8%), Toxocara canis (5%), Enterobius vermicularis (4%) and Strongyloides stercoralis (2%). There was no significant relationship between the intestinal parasites found in the soil samples and the study locations (p > 0.05). Soil physicochemical analysis indicated more dry soils (66%), with a mean temperature of 37°C and a mean pH of 6.89. No significant associations (p > 0.05) were observed between STH occurrence and moisture content, soil temperature and pH.

Conclusion: The widespread soil contamination observed highlights substantial environmental exposure risk and underscores the importance of integrated control measures, including environmental sanitation, routine deworming and continuous public health surveillance to reduce STH transmission in endemic settings such as in the studied area.