Multiple-clone activation of hypnozoites is the leading cause of relapse in Plasmodium vivax infection.

Background: Plasmodium vivax infection is characterized by a dormant hepatic stage, the hypnozoite that is activated at varying periods of time after clearance of the primary acute blood-stage, resulting in relapse. Differentiation between treatment failure and new infections requires characterization of initial infections, relapses, and clone multiplicity in vivax malaria infections.

Methodology/principal Findings: Parasite DNA obtained from primary/relapse paired blood samples of 30 patients with P.