Trial of pyrethroid impregnated bednets in an area of Tanzania holoendemic for malaria. Part 4. Effects on incidence of malaria infection.

Groups of about 30 children in each of five villages were given pyrimethamine-sulfadoxine to clear their malaria parasitaemia, and they were followed up with fortnightly blood slides. Parasitaemia returned rapidly in the absence of vector control, but more slowly when pyrethroid impregnated nets were in use or the houses had been sprayed with DDT. Variation between the incidence of malaria infection in these cases seemed to depend more on ecological or social factors than on the particular form of vector control adopted.