Schistosoma mansoni infections are associated with hepatosplenic organometry within the context of repeated praziquantel treatment and co-endemic infections of malaria, hepatitis B, and HIV: a population-based study in rural Uganda

BackgroundSchistosoma mansoni is a leading cause of hepatosplenic disease in sub-Saharan Africa. Yet, associations with current Schistosoma mansoni infections and hepatosplenic organometry remain unclear in the context of widespread mass drug administration and co-endemic infections. MethodsFrom January to February 2024, we conducted a community-based, cross-sectional study nested within the SchistoTrack cohort in three districts of Uganda. Liver and spleen dimensions were assessed via point-of-care B-mode ultrasound for 3121 individuals. Organ dimensions were classified using the standard deviations from height-standardized internal reference values derived from an infection-free population. Multinomial logistic regressions were run for children (5-17 years) and adults (18+ years) separately. Population attributable fractions (PAFs) were used to estimate the proportion of abnormal organometry statistically attributable to each infection. Key exposures were S. mansoni, malaria, human immunodeficiency virus (HIV), and hepatitis B virus (HBV) alongside a comprehensive set of social, biomedical, and other covariates controlled for. ResultsModerate-to-severe splenic enlargement was observed in 29.1% (438/1507) of children and 23.3% (376/1614) of adults. Among adults, 20.9% (337/1614) had left liver lobe enlargement and 18.8% (303/1614) had right liver lobe shrinkage. In children, severe splenic enlargement was statistically attributable to malaria (PAF 46.7%; Relative Risk Ratio (RRR) 3.96, 95% CI 2.64-5.92) and S. mansoni infection intensity (PAF 23.6%; RRR 1.12, 95% CI 1.04-1.20). In adults, S. mansoni intensity was associated with moderate left liver lobe enlargement (PAF 12.4%; RRR 1.11, 95% CI 1.04-1.18). In adults, HIV was associated with severe left liver lobe shrinkage (RRR 4.50, 95% CI 1.19-17.00) and severe splenomegaly (RRR 3.62, 95% CI 1.58-8.33), while HBV was associated only with severe left liver lobe shrinkage (RRR 2.54, 95% CI 1.07-6.03). Praziquantel treatment in the past year showed inconsistent associations and no clear protective pattern. ConclusionCurrent S. mansoni infection intensity remains associated with splenomegaly in children despite controlling for concurrent malaria positivity, and with hepatomegaly in adults despite HIV and HBV associations.