Insecticide Treated Nets–Technological & Operational Challenges (Commentary) (Report)
Mosquito nets treated with pyrethroid insecticides repel, disable and/or kill mosquitoes on contact. They provide personal protection to individual users, but when used by a high proportion of people in a community they have been shown to avert around haft the number of malaria cases (1,2). Collateral benefits of using insecticide treated nets (ITNs) include protection against nuisance of bed bugs, head rice and so on. A number of evaluations of the efficacy and effectiveness of ITNs have led to their use for prevention and control of malaria in different settings all over the world including India. Sahu et al (3) in this issue presented results of one such study in a malaria endemic area of India to show the considerable protective efficacy of insecticidal treatment of nets, especially with use of micro-encapsulated formulation than an emulsifiable concentrate formulation. The efficacy was superior with endophilic vectors and relatively lower with zoophilic species, and ITNs reduced malaria incidence markedly with nearly two-thirds of nets still usable after one and half years of routine community use. This study therefore adds another piece of evidence in favour of ITN technology which is undergoing considerable improvement. Many cultures in Asia have a long tradition of using mosquito nettings. Nets made up of a number of fabrics such as polyester, nylon, polyethylene and cotton are available commercially. With the development of the technology of treating nets with low dosage of pyrethroid insecticides, it has been possible to facilitate treatment of nets owned by people, as well as provide ITNs to socio-economically underprivileged societies often living in geographically difficult-to-reach areas with high malaria burden. For a number of technical and operational reasons, polyester nets have been found most suitable for treatment with a pyrethroid insecticide. Nets should be treated at least every six month intervals in areas with year round malaria transmission, or more frequently if they are washed more than two times in six months; they should be treated at least annually once just before the beginning of transmission season in low malaria endemic areas.