Background and Objective: In Kanchanaburi province, malaria caused by Plasmodium (P) vivax has increased in higher proportion compared to P. falciparum but little is known about genetic structure of P. vivax in this area. This study aimed to compare genetic characteristics of P. vivax isolates collected from malaria patients in Saiyok district of Kanchanaburi province in year 2010 and years 2013-2014.
Material and Methods: Two microsatellite markers, i.e. PV3.27 and PV3.502 were amplified by nested polymerase chain reaction, followed by fragment analysis of PCR products.
Result: P. vivax population of years 2013-2014 had statistical significance higher in genetic diversity than population of year 2010. Expected heterozygosity values of microsatellite marker, PV3.27 of year 2010 and 2013-2014 were 0.898 and 0.927; those values of PV3.502 were 0.873 and 0.912, respectively. Polyclonal infection of P. vivax population in Saiyok district, Kanchanaburi province was high. The average polyclonal infections were 52.1%; 54.8% in 2010 and 48.4% in 2013-2014. Mean multiplicity of infection was 2.35, 2.38, and 2.45 for microsatellite markers, PV3.27, PV3.502, and the combination, respectively.
Conclusion: P. vivax population in Saiyok district, Kanchanaburi province had increase in genetic diversity when compared between isolates collected in year 2010 and year 2013-2014. This suggests that there is still high malaria transmission and parasite evolution in this area.