In India, P. vivax malaria is treated with chloroquine (CQ) for 3 days and primaquine (PQ) for 14 days to prevent relapse. Controversies regarding the role of PQ at the dose used exist globally. Different molecular markers have been studied to differentiate between recrudescence, relapse and re-infection but not well established.
This study aims to determine the role of PQ in preventing recurrent P. vivax infections.
Two hundred and three P. vivax mono-infected patients who responded either to CQ (Group A) or CQ+PQ (Group B) were followed upto one year to determine the rate of recurrent infections. Nested PCR-RFLP method was adopted to compare the size polymorphisms of pvmsp1 and pvcsp genes of paired samples.
Recurrent vivax malaria was found 23 in Group A (26.7%) and 15 (16.5%) in Group B, without statistically significant difference (p=0.1034). Among 38 paired samples, 27 were with identical genotype and 11 were different. Thirty two recurrences were within 10 weeks and 6 after 10 weeks.
Recurrence rates in both groups were similar, so role of PQ at recommended dose in preventing relapse in P. vivax malaria is debatable. Hence, therapeutic efficacy studies of PQ with higher dose as advised by WHO is urgently required.
