Controlling Soil-transmitted Helminths in Malaysia’s Orang Asli: A Narrative Review of Routine Deworming and Water, Sanitation and Hygiene Interventions

Soil-transmitted helminth (STH) infections have persisted for decades among the Orang Asli, the indigenous peoples of Peninsular Malaysia, even as the wider country has largely eliminated them. The prevalence in children commonly reaches 60%–80%, with Trichuris trichiura the dominant species. This narrative review examines what routine deworming and water, sanitation and hygiene (WASH) interventions achieve against STH in these communities and how best to combine them. Four databases were searched for English language studies published between 2010 and 2026, identifying 16 primary Orang Asli and Malaysian studies, which were interpreted alongside international trials on deworming and WASH. Single-dose albendazole cleared Ascaris lumbricoides efficiently (cure rate near 90%) but cured only a minority of T. trichiura infections; a 3-day course with co-administered ivermectin improved whipworm cure, yet egg output rebounded within weeks and reinfection was rapid, with prevalence returning to as much as 94% of pre-treatment levels within a year. Because untreated adults and out-of-school children sustain household transmission, treating schoolchildren alone left transmission largely intact. WASH and culturally tailored health education reduced infection intensity and reinfection rates. However, their benefits depended on adoption and maintenance and pooled trials showed only modest, uncertain effects with little impact on T. trichiura . Rigorous trials of integrated deworming-plus-WASH programs in Orang Asli communities remain lacking. Deworming is therefore necessary but insufficient: sustainable control requires a stratified strategy pairing species-appropriate, community-wide deworming with maintained WASH and continuous health education, underpinned by intersectoral co-ordination and village level reinfection monitoring.