Background School-based deworming programmes can reduce morbidity attributable to soil-transmitted helminths
in children but do not interrupt transmission in the wider community. We assessed the effects of alternative mass
treatment strategies on community soil-transmitted helminth infection.
Methods In this cluster-randomised controlled trial, 120 community units (clusters) serving 150 000 households in
Kenya were randomly assigned (1:1:1) to receive albendazole through annual school-based treatment targeting
2–14 year olds or annual or biannual community-wide treatment targeting all ages. The primary outcome was
community hookworm prevalence, assessed at 12 and 24 months through repeat cross-sectional surveys. Secondary
outcomes were Ascaris lumbricoides and Trichuris trichiura prevalence, infection intensity of each soil-transmitted
helminth species, and treatment coverage and costs. Analysis was by intention to treat. This trial is registered with
ClinicalTrials.gov, number NCT02397772.
Findings After 24 months, prevalence of hookworm changed from 18·6% (95% CI 13·9–23·2) to 13·8% (10·5–17·0)
in the annual school-based treatment group, 17·9% (13·7–22·1) to 8·0% (6·0–10·1) in the annual community-wide
treatment group, and 20·6% (15·8–25·5) to 6·2% (4·9–7·5) in the biannual community-wide treatment group.
Relative to annual school-based treatment, the risk ratio for annual community-wide treatment was 0·59 (95% CI
0·42–0·83; p<0·001) and for biannual community-wide treatment was 0·46 (0·33–0·63; p<0·001). More modest
reductions in risk were observed after 12 months. Risk ratios were similar across demographic and socioeconomic
subgroups after 24 months. No adverse events related to albendazole were reported.
Interpretation Community-wide treatment was more effective in reducing hookworm prevalence and intensity than
school-based treatment, with little additional benefit of treating every 6 months, and was shown to be remarkably
equitable in coverage and effects.
Funding Bill & Melinda Gates Foundation, the Joint Global Health Trials Scheme of the Medical Research Council,
the UK Department for International Development, the Wellcome Trust, and the Children’s Investment Fund
Foundation.