Molecular surveillance of Plasmodium vivax drug resistance genes in Kanchanaburi province, Thailand, from 2022 to 2025

Background Plasmodium vivax remains prevalent in Thailand’s border regions, including Kanchanaburi, where concerns about antimalarial drug resistance persist. However, data on molecular markers associated with drug resistance in this area remain limited. This study aimed to describe the distribution of mutations in four putative P. vivax drug resistance genes in isolates from this region. Methods Blood samples (n = 100) were collected from patients with confirmed P. vivax infections in Kanchanaburi, Thailand, between 2022 and 2025. Genomic DNA was analyzed using nested PCR and Sanger sequencing to examine four putative drug resistance genes ( Pvmdr1, Pvdhfr, Pvdhps, and Pvcrt-o ). Results The Pvmdr1 Y976F mutation was detected in 7.07% of samples, with the M 958 Y 976 L 1076 haplotype being the most common (50.51%). The Pvcrt-o K10 insertion and K32T substitution were observed in 31.17% and 38.96% of isolates, respectively. The quadruple-mutant Pvdhfr haplotype ( I 57 R 58 M 61 T 117 ) was found in 42.42%, while the wild-type Pvdhps allele was present in 49.98%. Nineteen distinct multi-locus genotype profiles were identified, the most prevalent being M 958 Y 976 L 1076 – L 57 S 58 T 61 S 117 –A 383 K 512 A 553 –without K10 insertion/ T 32 (36.49%), followed by M 958 Y 976 L 1076 – F 57 S 58 T 61 S 117 –A 383 K 512 A 553 –with K10 insertion/ T 32 (12.16%). Conclusions This study provides the descriptive analysis of genetic diversity and multi-locus combinations of resistance-associated markers across four putative drug-resistance genes in P. vivax isolates from Kanchanaburi, Thailand, and offers updated data to inform and support malaria treatment strategies in this region.​