Prevalence of multiple human intestinal parasites across diverse environments in Madagascar

Background Intestinal parasitic infections affect more than 1·5 billion people globally, leading to severe health consequences such as malnutrition, anemia, diarrhea, and impaired cognitive development. Methodology/Principal findings Samples were collected from 3,872 individuals (all ages and both sexes) across 31 rural communities in Madagascar between 2013 and 2017, representing diverse ecological and socioeconomic regions. Intestinal parasite prevalence was assessed by fecal microscopy. Bayesian multilevel logistic regression models were used to estimate overall and regional prevalences while accounting for demographic and spatial variability. Parasite prevalence varied widely across Madagascar, with the highest rates observed for Ascaris lumbricoides (22·0%) and Trichuris trichiura (15·3%), followed by Hymenolepis nana (up to 10·5%), hookworm (up to 8·1%), Strongyloides (0·5%), and Schistosoma mansoni (0·5%). Infection burden was greatest in the northeast and southeast—especially among school-aged children aged 5–19. Sex differences were minor, except for higher hookworm prevalence in males. Conclusions/Significance This study provides the most comprehensive assessment to date of intestinal parasite prevalence across Madagascar, revealing that A. lumbricoides and T. trichiura infections were highly endemic in the humid eastern regions, while H. nana was most common in dry regions. The findings highlight substantial geographic heterogeneity and underscore the need for regionally targeted, multi-sectoral interventions, including improved sanitation and deworming.