High level of Schistosoma mansoni infection in pre-school children in Sierra Leone highlights the need in targeting this age group for praziquantel treatment

► Overall adjusted S. mansoni prevalence was 11% and mean intensity was 33.5 epg. ► In Kono: 27% of children were moderately or heavily infected with S. mansoni. ► Post-MDA the overall prevalence of A. lumbricoides and T. trichiura was low. ► Post-MDA hookworm prevalence was 22.8% and intensity 112.5 epg in hard to reach sites. ► Post-MDA the overall prevalence of any STH was 39.3% in hard to reach sites.