Molecular testing - P. vivax isolates from recurrent infections up to day 28 would be genotypically compared with those from day 0 using a panel of 14 highly polymorphic microsatellite markers in order to determine whether the recurrence is due to the only or major parasite population present in the original infection, to a minor parasite subpopulation that could be detected on day 0 or to a completely different parasite population.