Plasmodium falciparum resistance to artemisinin-based combination therapies (ACTs) started to crop up around 2007. Infections, especially in the Greater Mekong area of Southeast Asia, seemingly survived treatment. This was largely due to the pairing of artemisinin derivatives with older drugs that had existing resistance problems. But some experts think the emergence of partial resistance to artemisinin itself—which allows parasites to persist for longer in the body following treatment—could also play a role.
