The effect of permethrin-impregnated wall-curtains on malaria transmission and morbidity in the suburbs of Maputo, Mozambique.

The effect of nylon-netting wall-curtains impregnated with 0.5 g permethrin/m2 upon the biting rate of malaria vectors (Anopheles gambiae s.l. and An. funestus) and on the Plasmodium falciparum parasite rate, and morbidity due to malaria in children under five and between five and fourteen years was tested in the Maputo area. The curtains significantly lowered biting rates of both vector species inside curtained houses, but reduced inside resting and outside biting only in An. funestus. The percentage of children with falciparum parasitaemia fell significantly in curtained houses, and among their neighbours. However, parasite load and malaria morbidity in under fives was unaffected but malaria morbidity fell throughout the experimental area in 5 to 14-year-olds. This led to the speculation that malaria vectors inhibited from feeding in the vicinity of the curtains might have gone to feed in the adjacent control area.