Chloroquine-resistant Plasmodium vivax in Papua New Guinea

An Australian expatriate on regular weekly antimalarial prophylaxis with chloroquine base and Maloprim developed symptomatic Plasmodium vivax infection which failed to respond adequately to 600 mg of chloroquine base. More ominously, a resident of the Highlands region of Papua New Guinea contracted vivax malaria which failed to be cleared by 2400 mg chloroquine base administered over 4 d. Both patients had achieved appropriate blood and plasma concentrations of chloroquine after treatment. Chloroquine-resistant P. vivax is now a clinical fact in Papua New Guinea.