Molecular Epidemiology of P. vivax in Iran: High Diversity and Complex Sub-Structure Using Neutral Markers, but No Evidence of Y976F Mutation at pvmdr1.

Yaghoob Hamedi,Farzaneh Dehghan,Ric N Price,Reza Safari,Khojasteh Sharifi-Sarasiabi,Irene Handayuni,Sheren To,Hidayat Trimarsanto,Sarah Auburn

doi:10.1371/journal.pone.0166124

Abstract

BackgroundMalaria remains endemic at low levels in the south-eastern provinces of Iran bordering Afghanistan and Pakistan, with the majority of cases attributable to P. vivax. The national guidelines recommend chloroquine (CQ) as blood-stage treatment for uncomplicated P. vivax, but the large influx of imported cases enhances the risk of introducing CQ resistance (CQR).Methodology and Principal FindingsThe genetic diversity at pvmdr1, a putative modulator of CQR, and across nine putatively neutral short tandem repeat (STR) markers were assessed in P. vivax clinical isolates collected between April 2007 and January 2013 in Hormozgan Province, south-eastern Iran. One hundred blood samples were collected from patients with microscopy-confirmed P. vivax enrolled at one of five district clinics. In total 73 (73%) were autochthonous cases, 23 (23%) imported cases from Afghanistan or Pakistan, and 4 (4%) with unknown origin. 97% (97/100) isolates carried the F1076L mutation, but none carried the Y976F mutation. STR genotyping was successful in 71 (71%) isolates, including 57(57%) autochthonous and 11 (11%) imported cases. Analysis of population structure revealed 2 major sub-populations, K1 and K2, with further sub-structure within K2. The K1 sub-population had markedly lower diversity than K2 (HE = 0.06 vs HE = 0.82) suggesting that the sub-populations were sustained by distinct reservoirs with differing transmission dynamics, possibly reflecting local versus imported/introduced populations. No notable separation was observed between the local and imported cases although the sample size was limited.ConclusionsThe contrasting low versus high diversity in the two sub-populations (K1 and K2) infers that a combination of local transmission and cross-border malaria from higher transmission regions shape the genetic make-up of the P. vivax population in south-eastern Iran. There was no molecular evidence of CQR amongst the local or imported cases, but ongoing clinical surveillance is warranted.

Highlights

Malaria remains an important infectious disease in Iran
The contrasting low versus high diversity in the two sub-populations (K1 and K2) infers that a combination of local transmission and cross-border malaria from higher transmission regions shape the genetic make-up of the P. vivax population in south-eastern Iran
This study presents the first investigation of the genetic diversity and structure of P. vivax isolates in southern Iran using neutral short tandem repeat (STR) markers, and the first assessment of pvmdr1 polymorphism in the region

Summary

Introduction

Malaria remains an important infectious disease in Iran. National Malaria Control Programs (NMCPs) initiated in the 1950s were successful in reducing malaria cases in the south-eastern provinces and eliminating malaria in the northern Caspian region by 1977 [1,2,3]. The prevalence of malaria increased in the south-eastern provinces due to high rates of migration across porous borders with Afghanistan and Pakistan [3,4,5,6]. Antimalarial drug resistance presents further challenges to the containment and ultimate elimination of malaria in this region. Studies undertaken in regions with high-grade drug resistant P. vivax infection have reported severe and life-threatening disease in young children and pregnant women [9, 10]. Malaria remains endemic at low levels in the south-eastern provinces of Iran bordering Afghanistan and Pakistan, with the majority of cases attributable to P. vivax. The national guidelines recommend chloroquine (CQ) as blood-stage treatment for uncomplicated P. vivax, but the large influx of imported cases enhances the risk of introducing CQ resistance (CQR)

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Conclusion