Influence of Schistosoma mansoni infection on faecal calprotectin in the context of HIV, hepatitis B, and malaria co-infections

Background The role of gut inflammation for intestinal schistosomiasis remains poorly understood in chronically infected and repeatedly treated populations. Methods We conducted a cross-sectional study nested in the SchistoTrack cohort within Pakwach district, Uganda. In 2024, 640 participants aged 6-85 years were examined for Schistosoma mansoni by Kato- Katz. fCal concentration was measured by ELISA. fCal was analysed as binary outcomes (detectable, ≥100 μg/g, >250 μg/g) and natural log-transformed continuous values. Co-endemic infections (malaria, HIV, hepatitis B (HBV)) and diverse sociodemographic covariates were investigated in logistic regressions with covariate selection. Correlations of symptoms, medications, and circulating white blood cells (WBC) with infections and fCal were reported. Results 74.4% of participants had detectable fCal, 22.3% had fCal ≥100 μg/g, and 7.0% had fCal >250 μg/g. S. mansoni prevalence was 49.1% (median 144 eggs per gram, IQR 36-369). Infection intensity was positively associated with all fCal outcomes (detectable: OR 1.20, ≥100 μg/g: OR 1.11, >250 μg/g: OR 1.26; continuous: β = 0.06) while status was positively related to all but the continuous fCal outcome. HIV was associated with fCal ≥100 μg/g (OR 2.52), while malaria and HBV were uninformative. Spearman analyses revealed significant and weak positive correlations between fCal, WBCs (neutrophils, monocytes and lymphocytes), faecal occult blood, medications (praziquantel and anti- inflammatories) and gastrointestinal symptoms (blood in stool). Conclusions S. mansoni infections are characterised by persistent, clinically concerning levels of gut inflammation in chronically infected populations with repeated praziquantel treatment. Integration of fCal thresholds into clinical guidelines may improve management of schistosomiasis-related morbidity.