Induced primaquine resistance in vivax malaria.

01 Jul 1961

After 36 sequential subinoculations with suboptimal treatment of a single strain of vivax malaria, it has been possible to show a significant increase in trophozoite resistance to primaquine. In fact this resistance reached the point where maximum tolerated doses of primaquine had no action on parasitaemia and fever. This constitutes the maximum resistance that can be achieved in human volunteers.

During this programme gametocytes were observed to form and were transmitted through mosquitoes to the stage of mature and apparently viable sporozoites. These failed to infect man.

This induced resistance to primaquine should be one additional reason for always using primaquine in conjunction with a good blood schizontocide.

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