Relapsing vivax malaria

To the Editor: The Australian Defence Force (ADF) has sustained many cases of malaria following service in East Timor.1 To reliably prevent relapse of malaria caused by the Chesson strain of Plasmodium vivax present in this region, larger doses of primaquine are required2 (up to 6 mg/kg total dose,3 compared with > 3.5 mg/kg to prevent relapse of sub-Saharan vivax malaria4). The ADF uses 1500 mg chloroquine (total base) followed by 315 mg primaquine (total base) for the treatment of vivax malaria, which, in Australia, is commonly treated either without primaquine or with inadequate dosages of either chloroquine or primaquine.5