The suppression of malarial parasitaemia by pyrimethamine in combination with dapsone or sulphormethoxine

The antimalarial activity of pyrimethamine in combination either with dapsone or with sulphormethoxine, was compared with that of pyrimethamine alone. In this double-blind controlled study, 280 children, living in an area of stable P. falciparum malaria, were observed during one year. With pyrimethamine alone there was incomplete suppression of parasitaemia with crude parasite rates ranging from 2 to 25%. The first dose of the drug combinations produced a rapid clearance of parasitaemia, and weekly administration of the drug combinations sustained a virtually complete suppression of parasitaemia throughout the year. The drugs were well tolerated and no serious side-effects were encountered among the treated children.