Chloroquine Phosphate/Primaquine Phosphate

This research is intended to study the efficacy of CQ alone for P.vivax infection and also to study the recurrence rate among patients with P.vivax on standard dose of CQ and PQ. For this study, PQ will be withheld for 28 days so as to study the efficacy of CQ alone since masking effect over one another was found when CQ is given with PQ. So the investigators are not sure whether the recurrence is due to resistance to CQ or CQ concentration in blood is below therapeutic level or it is due to PQ is in inadequate dose. From this study the investigators will get findings like may be CQ is still working for P.vivax or no longer working for P.vivax due to resistance developed by P.vivax parasites. So for P.vivax which is not responding to CQ therapy, the investigators will go for second line treatment with ACT in a similar fashion as it is given for P. falciparum infection in Bhutan. And if the investigators find CQ is still working for P.vivax infection, the next level of study will be to compare higher dose of PQ with standard dose of PQ ( as practiced now) in lieu of bringing down the relapse rates in P. vivax infection.