Association between Schistosoma mansoni infection and fecal occult blood in schoolchildren in Mbita, Suba North Sub-County, western Kenya

Fecal occult blood (FOB) is a reliable indicator of bowel morbidity, yet its utility in the context of intestinal schistosomiasis remains inadequately characterized. To address this gap, we conducted a pre-post intervention study to evaluate the potential of FOB as a surrogate marker of Schistosoma mansoni -induced intestinal morbidity among preschool-aged (3–5 years) and school-aged (9–14 years) children in the Mbita Health Demographic Surveillance System, located along the shores and islands of Lake Victoria, Suba North sub-county, western Kenya. A total of 611 children from 10 primary schools were screened for S. mansoni infection prior to praziquantel (PZQ) treatment, and 584 were re-evaluated six weeks post-treatment. In addition to S. mansoni parasitological examination, FOB testing, malaria diagnosis, point-of-care hemoglobin measurement, and assessment of soil-transmitted helminth infections were performed both before and after treatment. Associations between S. mansoni infection and FOB positivity were analyzed using Pearson’s chi-square test and logistic regression. S. mansoni infection prevalence was high overall, particularly among SAC (77.4%) compared to PSAC (66.5%). Prior to treatment, over 75% of infected children were FOB-positive. Significant reductions in both S. mansoni infection and FOB positivity were observed six weeks after PZQ treatment (P < 0.01). Notably, PSAC residing on islands exhibited a higher likelihood of FOB positivity than those on the mainland. Our findings demonstrate a significant association between S. mansoni infection and FOB positivity. These results suggest that FOB testing may serve as a practical and scalable tool to monitor treatment-associated reductions in intestinal morbidity due to S. mansoni in endemic settings.