Strong association between high burden of soil-transmitted helminthiasis and household transmission among Malaysian Negritos, urging anthelmintic treatment beyond children

Abstract The Orang Asli (OA), Malaysia’s indigenous minority, continue to experience ongoing soil-transmitted helminth (STH) infections despite efforts including the Resettlement Programme (RPS). This study explores STH epidemiology and associated risks of moderate-to-heavy infections among 259 indigenous Negritos across four states in Peninsular Malaysia. Stool samples, anthropometrics, haemoglobin levels (finger-prick) and sociodemographic and environmental-sanitation factors via pretested questionnaires were collected. Parasitological examinations (direct faecal smear, formol-ether concentration, and Kato-Katz techniques) were thoroughly performed. The study revealed a 63.3% overall STH prevalence, with Trichuris trichiura (57.9%) being the most common, followed by Ascaris lumbricoides (35.5%) and hookworm (8.9%). Moderate-to-heavy infections were observed in 39.3% for T. trichiura and 48.9% for A. lumbricoides, with mixed infections of these two species being the most prevalent (50.6%). The risk for moderate-to-heavy infection increased significantly if other household members were infected (P