Efficacy of a 3-day artesunate-mefloquine combination in the treatment of uncomplicated falciparum malaria in Kanchanaburi province of Thailand

Background: In Kanchanaburi province located on the Thai-Myanmar border, Plasmodium falciparum parasites have developed significant resistance to commonly-used anti-malarials. For use against falciparum malaria, 2-day artesunate-mefloquine combination (MAS2) has recently been replaced by a 3-day artesunate-mefloquine combination (MAS3) that is an artemisinin-based combination therapy regimen recommended by the WHO. Objective: Investigate the efficacy and safety of MAS3 in the treatment of uncomplicated falciparum malaria in patients of Kanchaburi province. Methods: The study was conducted at Bongtee sub-district, Sai Yok district, Kanchanaburi province between June and November 2009. Fifty-one uncomplicated falciparum malaria patients were enrolled. Inclusion, exclusion and study method followed the WHO protocol for assessment and monitoring of antimalarial drug efficacy for the treatment of uncomplicated falciparum malaria. Patients received a MAS3 and were followed for 42 days. Results: All patients clinically recovered, but four patients were again parasitaemic on day 21, (1 patient) 28 (2 patients) and 42 (1 patient), respectively. Molecular analyses suggested that all recurrences were caused by recrudescence. There were no severe adverse events, but complaints of headache, gastrointestinal upset, nausea, and vomiting. Delay in parasite clearance was found. Proportion of parasite clearance on day 1, 2, 3 and 7 were 17.7%, 62.7%, 80.4%, and 100%, respectively. Conclusion: MAS3 is comparable to MAS2, and meet the WHO efficacy criteria for use against falciparum malaria, but the effect on parasite clearance was inferior to that of MAS2. Close monitoring evaluation is required.