Influence of sulfalene upon gametocytogenesis of Plasmodium falciparum and subsequent infection patterns in Anopheles stephensi

Quinine and/or sulfalene were administered to non-immune volunteers during various stages of infection with Plasmodium falciparum. Administration of each drug early in the asexual parasitemia reduced or prevented the subsequent formation of gametocytes. Later administration of sulfalene produced a subsequent sterilizing effect upon immature, non-circulating gametocytes, which were non-infective to Anopheles stephensi when they appeared in the circulating blood. Gametocytes present in the peripheral circulation at the time of administration of both drugs or appearing shortly thereafter were infective to A. stephensi.