Ensuring Life, Health and Prosperity for Future Generations

> Bed Nets Are Effective (Study Link)

PANNA summary: Using the pyrethroid insecticide lambdacyhalothrin to treat bed nets and using it to spray the inside walls of homes in northeast Tanzania proved to be equally effective at lowering the probability of malaria infection in children by 54-62%. However, treating bed nets used about one sixth the amount of insecticide as indoor spraying, and people in the area were much more enthusiastic about the bed nets, so the researchers conclude that pyrethroid-treated bed nets are more cost-effective than indoor spraying of the same chemicals.

Abstract: In an intensely malarious area in north-east Tanzania, microencapsulated lambdacyhalothrin was used in four villages for treatment of bednets (provided free of charge) and in another four villages the same insecticide was used for house spraying. Another four villages received neither intervention until the end of the trial but were monitored as controls. Bioassays showed prolonged persistence of the insecticidal residues. Light traps and ELISA testing showed reduction of the malaria vector populations and the sporozoite rates, leading to a reduction of about 90% in the entomological inoculation rate as a result of each treatment. Collections of blood fed mosquitoes showed no diversion from biting humans to biting animals. Incidence of re-infection was measured by weekly monitoring of cohorts of 60 children per village, after clearing preexisting infection with chlorproguanil-dapsone. The vector control was associated with a reduction in probability of re-infection per child per week by 54-62%, with no significant difference between the two vector control methods. Cross-sectional surveys for fever, parasitaemia, haemoglobin and weight showed association of high parasitaemia with fever and anaemia and beneficial effects of each intervention in reducing anaemia. However, passive surveillance by resident health assistants showed no evidence for reduced prevalence of fever or parasitaemia. Net treatment consumed only about one sixth as much insecticide as house spraying and it was concluded that the former intervention would work out cheaper and nets were actively demanded by the villagers, whereas spraying was only passively assented to. (London School of Hygiene and Tropical Medicine, UK.

9) Curtis, C.F., C.A. Maxwell, R.J. Finch, and K.J. Njunwa. A comparison of use of a pyrethroid either for house spraying or for bednet treatment against malaria vectors. Tropical Medicine and International Health. 3(8) 619-31, August 1998.


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