Efficacy of dihydroartemisinin-piperaquine plus primaquine treatment on vivax malaria in North Sumatera, Indonesia: a prospective observational study

Abstract Objectives. Plasmodium vivax malaria treated with dihydroartemisinin-piperaquine (DHA-PPQ) plus primaquine (PQ) in Indonesia remains challenging. Plasmodium falciparum resistance to DHA-PPQ was documented in Asia and it is suspected that this will also be a concern for P. vivax malaria. Thus, it is needed to test the efficacy on P. vivax regularly. Methods. Aprospective observational study was conducted at North Labuhan Batu Regency (North Sumatera, Indonesia). The outcomes were clinical and parasitological efficacy of the 3-day DHA-PPQ plus PQ therapy and the prevalence of pvmdr1, pvk12, and pvpm4 molecular markers of chloroquine and DHA-PPQ resistance. Results. During the 6-months study period, 100 patients were included and four were lost to follow-up. Ninety-six patients were included in the per-protocol analysis. A residual parasitemia was observed for a total of 16 patients: 10 patients on day 7 (10.7%), one patient on day 21 (1.0 %), and five patients on day 28 (5.3%). None of the residual parasitemia based on microscopy was associated with fever or symptoms. None of the molecular markers of ACT resistance was detected among the samples tested. Conclusions. This study did not provide evidence of a decreased efficacy of DHA-PPQ plus PQ regimen against P. vivax, but it highlighted the need for active surveillance of ACT efficacy, as it may be a warning signal before clinical therapeutic failure. A decreased sensitivity of P. vivax in North Sumatera would be an essential threat for Indonesia on its path toward malaria elimination.