[Failure to radical cure in Plasmodium vivax malaria]

Relapsing Plasmodium vivax malaria is due to activation of dormant intrahepatic parasitic forms known as hypnozoits. Primaquine is the only available drug effective against hypnozoits and, alongside a schizonticidal drug, constitutes the radical treatment of malaria. Failure of radical treatment is frequently attributed to inadequate dosing, poor adherence, or reinfection. However, several cases of radical treatment failure without these factors have been reported, inferring that metabolic properties of the host or tolerance mechanisms of the parasite may be implied. A case of malaria due to Plasmodium vivax acquired in the Amazonic region, treated outside endemic area, with multiple relapses despite adequate radical treatment is described.