Insecticide‐treated bed nets and curtains for preventing malaria
Abstract
Background
Malaria is an important cause of illness and death in many parts of the world, especially in sub‐Saharan Africa. There has been a renewed emphasis on preventive measures at community and individual levels. Insecticide‐treated nets (ITNs) are the most prominent malaria preventive measure for large‐scale deployment in highly endemic areas.
Objectives
To assess the impact of insecticide‐treated bed nets or curtains on mortality, malarial illness (life‐threatening and mild), malaria parasitaemia, anaemia, and spleen rates.
Search methods
I searched the Cochrane Infectious Diseases Group trials register (January 2003), CENTRAL (The Cochrane Library, Issue 1, 2003), MEDLINE (1966 to October 2003), EMBASE (1974 to November 2002), LILACS (1982 to January 2003), and reference lists of reviews, books, and trials. I handsearched journals, contacted researchers, funding agencies, and net and insecticide manufacturers.
Selection criteria
Individual and cluster randomized controlled trials of insecticide‐treated bed nets or curtains compared to nets without insecticide or no nets. Trials including only pregnant women were excluded.
Data collection and analysis
The reviewer and two independent assessors reviewed trials for inclusion. The reviewer assessed the risk of bias in the trials, and extracted and analysed data.
Main results
Fourteen cluster randomized and eight individually randomized controlled trials met the inclusion criteria. Five trials measured child mortality: ITNs provided 17% protective efficacy (PE) compared to no nets (relative rate 0.83, 95% confidence interval (CI) 0.76 to 0.90), and 23% PE compared to untreated nets (relative rate 0.77, 95% CI 0.63 to 0.95). About 5.5 lives (95% CI 3.39 to 7.67) can be saved each year for every 1000 children protected with ITNs. In areas with stable malaria, ITNs reduced the incidence of uncomplicated malarial episodes in areas of stable malaria by 50% compared to no nets, and 39% compared to untreated nets; and in areas of unstable malaria: by 62% for compared to no nets and 43% compared to untreated nets for Plasmodium falciparum episodes, and by 52% compared to no nets and 11% compared to untreated nets for P. vivax episodes. When compared to no nets and in areas of stable malaria, ITNs also had an impact on severe malaria (45% PE, 95% CI 20 to 63), parasite prevalence (13% PE), high parasitaemia (29% PE), splenomegaly (30% PE), and their use improved the average haemoglobin level in children by 1.7% packed cell volume.
Authors' conclusions
ITNs are highly effective in reducing childhood mortality and morbidity from malaria. Widespread access to ITNs is currently being advocated by Roll Back Malaria, but universal deployment will require major financial, technical, and operational inputs.
PICOs
Plain language summary
Insecticide‐treated nets can reduce deaths in children by one fifth and episodes of malaria by half.
Sleeping under mosquito nets treated with insecticide aims to prevent malaria in areas where the infection is common. They are widely promoted by international agencies and governments to reduce the bad effects of malaria on health. This review showed that good quality studies of impregnated nets markedly reduce child deaths and illnesses from malaria.
