Abstract
BackgroundPlasmodium vivax is the most widely distributed malaria parasite, and its drug resistance poses unique challenges to malaria elimination. The Greater Mekong Subregion (GMS) is known as the global epicenter of multidrug resistance. Surveillance of molecular markers associated with drug resistance in this area will help to inform drug policy.MethodsDry blood spots from 58 patients out of 109 with P. vivax infection between 2017, December and 2019, March were obtained from Yingjiang County, Yunnan Province, along the China–Myanmar border. Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o were amplified and sequenced to assess gene mutations. The polymorphism and prevalence of these molecular markers were analyzed.ResultsMutations in Pvdhfr at codons 57, 58, 61, 99 and 117 were detected in 27.59, 48.28, 27.59, 32.76 and 48.28% of the isolates, respectively. Single mutant haplotype (I13F57S58T61S99S117I173) was the most frequent (29.31%, 17/58), followed by double mutant haplotype (20.69%, 12/58). Of three types of tandem repeat variations of Pvdhfr, deletion type was the most common. Pvdhps showed a lower prevalence among mutation genotypes. Single mutant was dominant and accounted for 34.48% (20/58). Prevalence of Pvmdr1 mutations at codons 958 and 1076 were 100.00% and 84.48%, respectively. The proportion of double and single mutant types was 84.48% (49/58) and 15.52% (9/58), respectively. Eleven samples (18.97%, 11/58) showed K10 “AAG” insertion in chloroquine resistance transporter gene Pvcrt-o.ConclusionsThere was moderate diversity of molecular patterns of resistance markers of Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o in imported P. vivax cases to Yingjiang county in Western Yunnan, along the China–Myanmar border. Prevalence and molecular pattern of candidate drug resistance markers Pvdhfr, Pvdhps, Pvmdr1 and Pvcrt-o were demonstrated in this current study, which would help to update drug policy.
Highlights
Plasmodium vivax is the most widely distributed malaria parasite, and its drug resistance poses unique challenges to malaria elimination
No indigenous cases have been identified in Yunnan Province since 2017, P. vivax remains a challenge, with increasing evidence of abundant vector species richness and diversity, high malaria vulnerability resulting from mobile population, as well as drug resistance [9, 10]
Study site Yingjiang (Longitude 97°31′ ~ 98°16′,Latitude 24°24′ ~ 25°20′) is one of the 18 counties along the China– Myanmar border, located west of Yunnan Province. It was selected as the study site due to its long borderline with Kachin State, Myanmar and being well documented as an epidemic area of resistant P. falciparum [18]
Summary
Plasmodium vivax is the most widely distributed malaria parasite, and its drug resistance poses unique challenges to malaria elimination. (SP) in the 1970s, mefloquine in the late 1990s, and artemisinin in 2008, and spread progressively throughout other malaria-endemic areas [3,4,5,6]. This has raised concern from the World Health Organization (WHO) and local health authorities [2, 7, 8]. No indigenous cases have been identified in Yunnan Province since 2017, P. vivax remains a challenge, with increasing evidence of abundant vector species richness and diversity, high malaria vulnerability resulting from mobile population, as well as drug resistance [9, 10]. In Myanmar, the proportion of malaria cases caused by P. vivax has increased steadily since 2012 [11]
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