SPECIFIC AND NONSPECIFIC RESPONSES TO PLASMODIUM-FALCIPARUM BLOOD-STAGE PARASITES AND OBSERVATIONS ON THE GAMETOCYTEMIA IN SCHOOLCHILDREN LIVING IN A MALARIA-ENDEMIC AREA OF MOZAMBIQUE

We have observed specific and nonspecific reactivities to the asexual stages and gametocytes of Plasmodium falciparum and examined the effec t of chloroquine and Fansidar(TM) (pyrimethamine/sulfadoxine) on the d ynamics of gametocytemia. Schoolchildren peripheral blood films positi ve for P. falciparum gametocytes were identified in a malaria-endemic area of Mozambique. The children were randomly allocated into two grou ps to receive chloroquine or pyrimethamine/sulfadoxine, and were follo wed for 28 days after treatment, In patients harboring drug-sensitive parasites, asexual parasitemias were cleared by day 4, but gametocytes persisted for an additional 17 days. The prevalence of the asexual pa rasites was 67.6% in the chloroquine-treated group at day 0 and 61.1% at day 28, whereas in the pyrimethamine/sulfadoxine treated group, the initial parasite positive prevalence of 70.7% was reduced to 2.4% at day 28, suggesting a high prevalence of chloroquine-resistant parasite s. On day 0, gametocyte prevalence was 59.5% in the chloroquine-treate d group and in 68.3% in the pyrimethamine/sulfadoxine-treated group; t hese values were reduced to 5.6% and 2.4%, respectively, at day 28. Ou r results suggest strongly that there is no induction of gametocytogen esis by either course of chemotherapy.