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Background  Recent emergence of artemisinin-resistant  P. falciparum  has posed a serious hindrance to the elimination of malaria in the Greater Mekong Subregion. Parasite clearance time, a measure of change in peripheral parasitaemia in a sequence of samples taken after treatment, can be used to reflect the susceptibility of parasites or the efficiency of antimalarials. The association of genetic polymorphisms and artemisinin resistance has been documented. This study aims to examine clearance time of  P. falciparum  and  P. vivax  parasitemia as well as putative gene mutations associated with residual or recurred parasitemia in Myanmar.    Methods  A total of 63  P. falciparum  and 130  P. vivax  samples collected from two internally-displaced populations and one surrounding village were examined for parasitemia changes. At least four samples were taken from each patient, at the first day of diagnosis up to 3 months following the initial treatment. The amount of parasite gene copy number was estimated using quantitative real-time PCR based on a species-specific region of the 18S rRNA gene. For samples that showed residual or recurred parasitemia after treatment, microsatellites were used to identify the ‘post-treatment’ parasite genotype and compared such with the ‘pre-treatment’ genotype. Mutations in genes  pfcrt ,  pfmdr 1,  pfatp 6,  pfmrp 1 and  pfK 13 that are potentially associated with ACT resistance were examined to identify if mutation is a factor for residual or persistent parasitemia.    Results  Over 30 % of the  P. falciprium  infections showed delayed clearance of parasitemia after 2–3 days of treatment and 9.5 % showed recurred parasitemia. Mutations in codon 876 of the  pfmrp1  corroborated significance association with slow clearance time. However, no association was observed in the variation in  pfmdr1  gene copy number as well as mutations of various codonsin pfatp6, pfcrt,  and  pfK13  with clearance time. For  P. vivax , over 95 % of the infections indicated cleared parasitemia at days 2–3 of treatment. Four samples were found to be re-infected with new parasite strains based on microsatellite genotypes after initial treatment.    Conclusion  The appearance of  P.falciparum  infected samples showing delayed clearance or recurred parasitemia after treatment raises concerns on current treatment and ACT drug resistance.    Electronic supplementary material  The online version of this article (doi:10.1186/s12879-016-1482-6) contains supplementary material, which is available to authorized users.

bmc infectious diseases

Examining Plasmodium falciparum and P. vivax clearance subsequent to antimalarial drug treatment in the Myanmar-China border area based on quantitative real-time polymerase chain reaction