SHORT REPORT - GAMETOCYTES, CHLOROQUINE PRESSURE, AND THE RELATIVE PARASITE SURVIVAL ADVANTAGE OF RESISTANT STRAINS OF FALCIPARUM-MALARIA IN WEST-AFRICA

Patients with Plasmodium falciparum infections were selected with an i n vivo chloroquine sensitivity assay. Fourteen days after treatment, t he gametocytes were studied in relation to asexual parasite responses classified as drug-sensitive or showing RI or RII resistance. Gametocy te prevalence and density appeared significantly higher in RII than RI strains and higher in RI than in sensitive strains. This finding on g ametocyte variation in vivo may explain why the RII type of chloroquin e resistance has became more prevalent than RI everywhere in tropical Africa in the short time since its emergence. The biological and epide miologic advantage of chloroquine-resistant malaria mediated through g ametocytes is discussed in the context of the present drug pressure in Africa.