[Epidemiological and therapeutic aspects of plasmodial infection from Plasmodium vivax]

A major challenge for successful treatment of Plasmodium vivax malaria is prevention of recurrence due to activation of dormant intrahepatic parasitic forms called hypnozoits. As a result of strain variability, recurrences are unpredictable and can occur months or even years after initial infection. Prevention requires elimination of both erythrocytic and hepatic parasite forms by combined use of chloroquine and primaquine. Primaquine is the only commercially available drug against hypnozoits. Several factors must be taken into account in planning treatment regimens. One factor is drug resistance of vivax strains, which as observed for Plasmodium falciparum strains is variable between geographical areas. Another factor is potential co-infection by Plasmodium vivax and falciparum, which is increasingly common. For optimal efficacy, treatment regimens must be adjusted with regard to dosage of primaquine and association with halofantrine, mefloquine or other new antimalarial agents. No regimen completely rules out the risk of recurrence.