Impact of permethrin-treated bed nets on malaria and all-cause morbidity in young children in an area of intense perennial malaria transmission in western Kenya: cross-sectional survey

Abstract

Information on the impact of insecticide (permethrin)-treated bed nets (ITNs) from randomized con-trolled trials in areas of intense perennial malaria transmission is limited. As part of a large-scale, community-based,group-randomized controlled trial of the effect of ITNs on childhood mortality in a holoendemic area in western Kenya,we conducted three cross-sectional surveys in 60 villages to assess the impact of ITNs on morbidity in 1,890 children less than three years old. Children in ITN and control villages were comparablepre-intervention, but after the introductionof ITNs, children in intervention villages were less likely to have recently experienced illness requiring treatment(protective efficacy [95% confidence intervals]=15% [1−26%]), have an enlarged spleen (32% [20−43%]), be para-sitemic (19% [11−27%]), have clinical malaria (44% [6−66%]), have moderately severe anemia (hemoglobin level < 7.0g/dL; 39% [18−54%]), or have a pruritic body rash, presumably from reducednuisance insect bites (38% [24−50%]). Useof ITNs was also associated with significantly higher mean weight-for-age Z-scores and mid-upper arm circumferences.There was no evidence, however, that ITNs reduced the risk of helminth infections, diarrhea, or upper or lower respiratory tract infections. The ITNs substantially reduced malaria-associated morbidity and improved weight gain in young children in this area of intense perennial malaria transmission.