Effective use of
anti-malarial drugs is key to reducing the transmission potential of Plasmodium vivax. In patients presenting with symptomatic disease, treatment with potent and relatively slowly eliminated blood schizontocidal regimens administered concurrently with a supervised course of 7 mg/kg
primaquine over 7-14 days has potential to exert the greatest transmission-blocking benefit. Given the spread of
chloroquine-resistant P. vivax strains, the
artemisinin combination
therapies dihydroartemisinin +
piperaquine and
artesunate +
mefloquine are currently the most assured means of preventing P. vivax recrudescence. Preliminary evidence suggests that, like
chloroquine, these combinations potentiate the hypnozoitocidal effect of
primaquine, but further supportive evidence is required. In view of the high rate of P. vivax relapse following falciparum
infections in co-endemic regions, there is a strong argument for broadening current radical cure policy to include the administration of hypnozoitocidal doses of
primaquine to patients with
Plasmodium falciparum malaria. The most important reservoir for P. vivax transmission is likely to be very low-density,
asymptomatic infections, the majority of which will arise from liver-stage relapses. Therefore, judicious
mass administration of hypnozoitocidal
therapy will reduce transmission of P. vivax to a greater extent than strategies focused on treatment of symptomatic patients. An efficacious hypnozoitocidal agent with a short curative treatment course would be particularly useful in
mass drug administration campaigns.