# Association between Schistosoma mansoni infection and fecal occult blood in schoolchildren in Mbita, Suba North sub-county, western Kenya

## TL;DR

This study shows that fecal occult blood testing can help track intestinal damage caused by Schistosoma mansoni infection in children in Kenya.

## Contribution

The study demonstrates that fecal occult blood is a useful indicator of intestinal morbidity caused by S. mansoni infection in endemic areas.

## Key findings

- High prevalence of S. mansoni infection was found in both preschool and school-aged children.
- FOB positivity was strongly associated with S. mansoni infection before treatment.
- Praziquantel treatment significantly reduced both infection and FOB positivity.

## Abstract

Schistosoma mansoni infection is highly prevalent in sub-Saharan Africa and is associated with significant intestinal morbidity in children. Current monitoring tools primarily assess infection status and intensity, which may underestimate the disease burden. Fecal occult blood (FOB) is a reliable indicator of bowel morbidity; however, its utility in intestinal schistosomiasis remains inadequately characterized. This study aimed to evaluate FOB as a surrogate marker of S. mansoni-induced intestinal morbidity among children in endemic areas of Kenya.

A pre–post intervention study was conducted among preschool-aged (3–5 years) and school-aged (9–14 years) children in the Mbita Health Demographic Surveillance System 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 before praziquantel treatment, and 584 were re-evaluated 6 weeks post-treatment. In addition to parasitological examination for S. mansoni, FOB testing, malaria diagnosis, point-of-care hemoglobin measurement, and soil-transmitted helminth assessments 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 before treatment, affecting 66.5% of preschool-aged and 77.4% of school-aged children. Among S. mansoni-infected children, more than three-quarters tested positive for FOB. Six weeks after praziquantel treatment, the prevalence of both S. mansoni infection and FOB positivity declined significantly (infection: 19–21%; FOB: 25–29%; P < 0.01). Before treatment, preschool-aged children residing on islands had twice the odds of FOB positivity compared to those on the mainland (AOR = 2.0; 95% CI 1.2–3.4; P = 0.01), although this association was no longer evident post-treatment.

Our findings demonstrate a significant association between S. mansoni infection and FOB positivity. These results suggest that FOB testing could be a useful indicator for monitoring treatment-associated reductions in intestinal morbidity due to S. mansoni in endemic settings.