Effects of very low dose primaquine on transmissibility of falciparum malaria. Malariatherapy with Plasmodium falciparum (Panama strain) in two patients who were treated with primaquine 3 mg daily (starting at vertical yellow arrow) as reported by Young et al. Daily direct mosquito feeding was performed. Black line is asexual parasitaemia, vertical lines are temperature (fever), vertical boxes represent mosquito feeds and dark hatching shows proportion infected. Mosquitoes (10 each) were dissected for oocysts and sporozoites; red + = infected (≥8 of 10), grey 0 = none infected. Note that infectivity persisted until the fourth day of treatment in patient 1316 (upper panel), and the second day in patient 1321 (lower panel) and also that the young circulating gametocytes in patient 1316 were initially not infectious. There was a moderate and delayed effect on gametocytaemia (red dashed line).