In vitro drug sensitivity testing in Plasmodium vivax.

The possibility of short-term in vitro cultivation, i.e. growth of asexual erythrocytic stages up to the stage of mature schizonts, permits in principle the development of drug sensitivity tests also for Plasmodium vivax. In the absence of a sequestration of erythrocytes carrying the advanced stages of schizogony, asexual parasites of all stages may be seen in the peripheral blood of patients infected with P. vivax. This precludes schizont maturation tests since schizont development will be unduly influenced by the number of advanced trophozoites. A test system reflecting the age composition of the parasite population and its progression without and under the influence of inhibitors was found to yield precise results also in the higher IC ranges. The population-based test procedure would also permit the identification of any stage-specific impact of antimalarial agents.