In areas where malaria remains entrenched, novel transmission-reducing interventions are essential for malaria elimination. We report the impact of screening-and-treatment of asymptomatic schoolchildren (N=705) on gametocyte - the parasite stage responsible for human-to-mosquito transmission - carriage and use concomitant household-based surveys to predict the potential reduction in transmission in the surrounding community. Among 179 students with gametocyte-containing infections, 84% had positive malaria rapid diagnostic tests. While gametocyte burden remained constant in untreated children, treatment with artemether-lumefantrine reduced the gametocyte prevalence (p<0.0001) from 51.8% to 9.7% and geometric mean gametocyte density (p=0.008) from 0.52 to 0.05 gametocytes/microliter. Based on these estimates, the gametocyte burden in the community could be reduced by 25-55% depending on the season and the measure used to characterize gametocyte carriage. Thus, school-based interventions to treat asymptomatic infections may be a high-yield approach to not only improve the health and education of schoolchildren, but also decrease malaria transmission.

Background: In areas highly endemic for malaria, Plasmodium falciparum (Pf) infection prevalence peaks in school-age children, adversely affecting their health and education. School-based intermittent preventive treatment reduces this burden, however concerns about cost and widespread use of antimalarial drugs have limited enthusiasm for this approach. School-based screening-and-treatment is an attractive alternative. We conducted a school-based cohort study to evaluate the impact of screening-and-treatment on the prevalence of Pf infection and anemia in two different transmission settings. Methods: We screened 704 students in four Malawian primary schools for Pf infection using rapid diagnostic tests (RDTs). Those testing positive were treated with artemether-lumefantrine. Outcomes were Pf infections detected by microscopy or PCR and anemia after six weeks. Results: Prevalence of infection by RDT at screening was 37% (range among schools 9-64%). We detected a significant reduction after six weeks in infections by microscopy (adjusted relative reduction (aRR) 47.1%, p<0.0001) and PCR (aRR 23.1%, p<0.0001), but no reduction in anemia. In low, seasonal prevalence areas, sub-patent infections at screening led to persistent infection, but not disease, during follow-up. In high transmission settings, new infections frequently occurred within six weeks after treatment. Conclusions: School-based screening-and-treatment reduced Pf infection but not anemia. This approach could be enhanced in low transmission settings by using more sensitive screening tests and in high transmission settings by repeating the intervention or using longer acting drugs.