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 controlled 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 comparable pre-intervention, but after the introduction of ITNs, children in intervention villages were less likely to have recently experienced illness requiring treatment (protective efficacy [95% confidence intervals] ‫ס‬ 15% [1−26%]), have an enlarged spleen (32% [20−43%]), be parasitemic (19% [11−27%]), have clinical malaria (44% [6−66%]), have moderately severe anemia (hemoglobin level < 7.0 g/dL; 39% [18−54%]), or have a pruritic body rash, presumably from reduced nuisance insect bites (38% [24−50%]). Use of ITNs was also associated with significantly higher mean weight-forage 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.

Prevalence and Severity of Malnutrition in Pre-School Children in a Rural Area of Western Kenya

“…15 Between October 1996 and December 1998, three crosssectional surveys were conducted in 60 villages to determine the impact of ITNs on all-cause morbidity in pre-school children. 10 The baseline survey (survey 0) was conducted just prior to the distribution of the ITNs in December 1996 and used two-stage random cluster sampling (27 village-clusters, then sampling children from these). The other two surveys (survey 1 and survey 2) were conducted in February−March and November−December 1998; 14 and 22 months after half of the villages (selected at random) had received ITNs.…”

“…Full details of the design and methods used in these surveys and the impact of ITNs on nutritional parameters have been published elsewhere. 10 Measurements were performed according to standard procedures of the World Health Organization. 16 Children less than six months old were undressed and weighed to the nearest 10 grams using a 10 kg ± 10 g hanging weighing scale (Salter, Smethwick, United Kingdom).…”

“…10 The analysis of the prevalence and mean Z-scores was therefore weighted by age, using the known age distribution of the children enrolled in the ITN trial as the reference. The analysis was also weighted by survey such that data from each survey contributed equally to the final data set for children less than 36 months of age (33.3% each).…”

“…As part of a large, randomized, controlled intervention study of insecticide (permethrin)-treated bed nets (ITNs), we monitored all-cause morbidity and standard parameters of malnutrition in a series of cross-sectional surveys involving a random selection of pre-school children. 10 The aim of this report is to describe the nutritional status of these children and to determine the main age groups at risk of malnutrition. Only data collected prior to the introduction of ITNs, and subsequent data from control villages are used for this analysis.…”

Community trial of insecticide-treated bed net use promotion in southern Ghana: the Net Use Intervention study

“…Based on strong evidence that they reduce malaria transmission and related morbidity and child mortality [7][8][9][10], local and international organizations in Africa have been promoting and distributing insecticide-treated nets (ITNs) for more than 10 years. Although this has resulted in greater ITN availability in SSA countries, getting people to use ITNs correctly and consistently is difficult [11][12][13][14][15][16].…”