Preliminary data in a recently completed RCT evaluating artesunate-mefloquine vs chloroquine for P. vivax showed up to 36% P. vivax recurrence with chloroquine monotherapy by day 28 post treatment without primaquine. Based on these data blood stage chloroquine treatment failure rates should also be evaluated in the context of standard concurrent (rather than delayed) liver stage primaquine dosing, due to both its potential blood stage synergistic effect in addition to known decreased recurrence rates. As artemether-lumefantrine is one of the current first line Ministry of Health ACTs used in Sabah with a lower adverse event profile compared to artesunate-mefloquine, this was recommended as the more appropriate ACT to evaluate against chloroquine.