There is also growing support for artemisinin-based combination therapy (ACT) as a unified first line treatment choice in areas co-endemic for P. falciparum and P. vivax, as adopted by a small number of countries including PNG, Solomon Islands, Vanuatu and Papua, Indonesia, due to the regional increase of chloroquine-resistant P. vivax, and ongoing concerns over the microscopic misdiagnosis of Plasmodium species. This is also particularly relevant for P. knowlesi malaria, as it is frequently misidentified on microscopy as P. falciparum and P. malariae due to morphological similarities in the early trophozoite, and late trophozoite and schizont life stages respectively, with studies showing up to 80% of P. malariae and 7-12% of P. falciparum in this region are actually P. knowlesi when definitively evaluated with PCR. Misdiagnosis has concerning treatment implications, as although P. knowlesi has been shown to respond well to ACT and chloroquine, unlike P. malariae, knowlesi malaria has a rapid 24-hour replication rate and can cause hyperparasitaemia, severe complications and fatal outcomes, while the inadvertent use of chloroquine for widely chloroquine-resistant P. falciparum may also have fatal consequences.