The effects of primaquine alone on asexual and sexual parasitaemia in falciparum malaria. Volunteer study reported by Rieckmann et al.  in which primaquine (45 mg base) only was given. The volunteers were infected with the Malayan Camp strain of P. falciparum. Anopheles stephensi was used as the vector. Volunteer 3 data are shown. Gametocytaemia was quantitated by microscopy, oocysts and sporozoites were assessed by microscopy after dissection (arrows are the days when mosquitoes were dissected, the numerator is the number positive, the denominator is the number of mosquitoes dissected). The subsequent infectivity of these mosquitoes (i.e., from the same batches) to other volunteers was also assessed; a different, healthy, non-immune volunteer was bitten by 75 mosquitoes before, and 12, 24 and 48 hours after primaquine had been given to volunteer 3; + (red) denotes that the volunteer became infected with falciparum malaria, 0 denotes the volunteer did not become infected.