Self-protection from malaria vectors in Pakistan: an evaluation of popular existing methods and appropriate new techniques in Afghan refugee communities

Abstract

Experimental huts were used to measure the impact of several techniques for self-protection from malaria vectors in Pakistan. An electric fan, pyrethrum coils, untreated curtains, pyrethroid-vaporizing mats and permethrin-impregnated curtains reduced the total catches of blood-fed Anopheles stephensi by 27%, 36%, 47%, 56% and 65%, respectively. The most marked effect of all the interventions was in reducing the numbers of mosquitoes entering the huts, although all the techniques, except for the untreated curtain, also reduced the proportion of mosquitoes inside the hut which fed. Although the trends seen were similar for both anopheline (all An. stephensi) and culicine mosquitoes, they were more pronounced in the culicines. Social surveys were conducted on current self-protection practices. The social and economic constraints associated with each of the various techniques are discussed. All the strategies were shown to offer a degree of protection and their use should be encouraged. Impregnated curtains seem especially promising. Pyrethroid-impregnated bednets have been widely promoted in eastern Afghanistan since 1991 and have the advantage of providing protection when people sleep outside during the summer. However, surveys show that some owners stop using their nets in late autumn, despite the continued risk of malaria. People should be encouraged to use their bednets as impregnated curtains rather than putting them into storage.