EFFICACY OF PERMETHRIN-TREATED BED NETS IN THE PREVENTION OF MORTALITY IN YOUNG CHILDREN IN AN AREA OF HIGH PERENNIAL MALARIA TRANSMISSION IN WESTERN KENYA

Abstract. A group-randomized controlled trial of insecticide (permethrin)-treated bed nets (ITNs) was conducted in an area of high perennial malaria transmission in western Kenya to test the effect of ITNs on all-cause mortality in children 1–59 months of age. Child deaths were monitored over a two-year period by biannual household census in Asembo (1997–1998) and in Gem (1998–1999). Overall, 1,722 deaths occurred in children 1–59 months followed for 35,932 child-years. Crude mortality rates/1,000 child-years were 51.9 versus 43.9 in control and ITN villages in children 1–59 months old. The protective efficacy (PE) (95 % confidence interval) adjusted for age, study year, study site, and season was 16 % (6–25%). Corresponding figures in 1–11- and 12–59-month-old children in control and ITN villages were 133.3 versus 102.3, PE 23 % (11–34%) and 31.1 versus 28.7, PE 7 % (-6–19%). The numbers of lives saved/1,000 child-years were 8, 31, and 2 for the groups 1–59, 1–11, and 12–59 months old, respectively. Stratified analysis by time to insecticide re-treatment showed that the PE of ITNs re-treated per study protocol (every six months) was 20% (10–29%), overall and 26 % (12–37%) and 14 % (−1–26%) in 1–11- and 12–59-month-old children, respectively. ITNs prevent approximately one in four infant deaths in areas of intense perennial malaria transmission, but their efficacy is compromised if re-treatment is delayed beyond six months