Molecular inference of sources and spreading patterns of Plasmodium falciparum malaria parasites in internally displaced persons settlements in Myanmar–China border area

Eugenia Lo,Guofa Zhou,Winny Oo,Ming-Chieh Lee,Elisabeth Baum,Philip L Felgner,Zhaoqing Yang,Liwang Cui,Guiyun Yan

doi:10.1016/j.meegid.2015.05.002

Abstract

In Myanmar, civil unrest and establishment of internally displaced persons (IDP) settlement along the Myanmar–China border have impacted malaria transmission. The growing IDP populations raise deep concerns about health impact on local communities. Microsatellite markers were used to examine the source and spreading patterns of Plasmodium falciparum between IDP settlement and surrounding villages in Myanmar along the China border. Genotypic structure of P. falciparum was compared over the past three years from the same area and the demographic history was inferred to determine the source of recent infections. In addition, we examined if border migration is a factor of P. falciparum infections in China by determining gene flow patterns across borders. Compared to local community, the IDP samples showed a reduced and consistently lower genetic diversity over the past three years. A strong signature of genetic bottleneck was detected in the IDP samples. P. falciparum infections from the border regions in China were genetically similar to Myanmar and parasite gene flow was not constrained by geographical distance. Reduced genetic diversity of P. falciparum suggested intense malaria control within the IDP settlement. Human movement was a key factor to the spread of malaria both locally in Myanmar and across the international border.

Highlights

Since the inception of the Roll Back Malaria Initiative by World Health Organization (WHO) in 1999, malaria control has been greatly intensified in endemic countries
300 samples that were diagnosed with P. falciparum infections were collected from clinics or hospitals located in two internally displaced persons (IDP) settlements, Je Yang Hka (JYH) and Hpum Lum Yang (HLY), and four surrounding villages/towns including military base (CMH), Ja Htu Kawng (JHK), Laiza (LZCH), and Mai Sak Pa (MSP) in Myanmar along the international border of China, in addition to two town hospitals Tengchong (TC) and Yingjiang (YJ) in Yunnan, China (Fig. 1; Supplementary Table S1)
Notwithstanding that displaced populations are vulnerable to infectious diseases like malaria, it is more concerning that the local community around displaced populations could be at greater increased risks by human movement and poor health infrastructure

Summary

Introduction

Since the inception of the Roll Back Malaria Initiative by World Health Organization (WHO) in 1999, malaria control has been greatly intensified in endemic countries. The number of malaria cases and malaria-induced mortality in Myanmar has been consistently high for the past three decades (Cui et al, 2012b). Factors such as the emergence/spread of Plasmodium falciparum resistance to artemisinins and P. vivax resistance to chloroquine, inadequate epidemiological data to assess malaria situations, complex vectorial systems, and above all civil unrest make malaria control very difficult in Myanmar (Coker et al, 2011; Cui et al, 2012a,b; Delacollette et al, 2009; Cheeseman et al, 2012; Phyo et al, 2012; Li et al, 2013)

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