Figure 1.

Recrudescence following antimalarial drug exposure. Recrudescence following four exposures to dihydroartemisinin or pyrimethamine was assessed by microscopy of Giemsa-stained blood smears. Asynchronous artemisinin-resistant (C9) and parent D6 ring-stage parasites were co-cultured 1: 1 and exposed to 700 nM dihydroartemisinin or 10 μM pyrimethamine for 48 h; data for sham exposure with 0.25% DMSO are not shown. C9 and the mixed culture recovered up to 2–3 days earlier than D6 when exposed to dihydroartemisinin. When exposed to pyrimethamine mixed culture, recrudescence was similar to that of drug-susceptible D6 in monoculture.