THE CONTRIBUTION OF REPELLENT SOAP TO MALARIA CONTROL

A study about the acceptability, protective efficacy, effectiveness, a nd cost of a repellent soap containing 20% diethyltoluamide and 0.5% p ermethrin was carried out on the Pacific coast of Ecuador and Peru, wh ere malaria is endemic and the transmission is seasonal. The malaria v ectors were Anopheles albimanus, An. punctimacula, and An. psendopunct ipennis in Ecuador and An. albimanus in Peru. Comparing the hourly mos quito bites on human subjects with and without the protection of the r epellent soap, it showed that inactive, protected subjects were bitten 94.2% less than unprotected controls 2 hr after application of the so ap. This protective efficacy was reduced to 81% after 6 hr. In persons physically active for 3 hr after application, the efficacy of the soa p was 67% in the fourth hour after application and 52% in the sixth ho ur after application. Sweating decreased the protective efficacy of th e soap even more. In a community-based malaria control program, the so ap was introduced by community health promoters. Acceptance was good w hen it was given free of charge but reduced dramatically when it was s old. People used the soap mainly because of the nuisance of mosquitoes . The application was generally done correctly. However, no significan t impact on the incidence of malaria episodes could be shown when comp aring intervention communities with control communities, either in Ecu ador, where the proportion of Plasmodium falciparum cases was high, or in Peru, where P. vivax was the only species of Plasmodium seen. This can probably be explained by the limited use of soap and the shift of mosquito bites from users to nonusers of the repellent soap. The cost of a soap program would be $4.60 (USA) per person per year, which see ms to be quite high in terms of cost of soap and its distribution rela ted to people's low cash income. The implications of the introduction of repellent soap into a control program are discussed.