Dynamics of Plasmodium vivax populations in border areas of the Greater Mekong sub-region during malaria elimination

• Published in: Malaria Journal
• Main Authors: Yuling Li, Yubing Hu, Yan Zhao, Qinghui Wang, Huguette Gaelle Ngassa Mbenda, Veerayuth Kittichai, Saranath Lawpoolsri, Jetsumon Sattabongkot, Lynette Menezes, Xiaoming Liu, Liwang Cui, Yaming Cao
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2020
• Subjects: Malaria; Plasmodium vivax; Epidemiology; Population genetics; Microsatellites; Greater Mekong sub-region; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-020-03221-9; https://doaj.org/article/8732953d7ea64ad49f6a75c429a673bc

Abstract Background Countries within the Greater Mekong Sub-region (GMS) of Southeast Asia have committed to eliminating malaria by 2030. Although the malaria situation has greatly improved, malaria transmission remains at international border regions. In some areas, Plasmodium vivax has become the predominant parasite. To gain a better understanding of transmission dynamics, knowledge on the changes of P. vivax populations after the scale-up of control interventions will guide more effective targeted control efforts. Methods This study investigated genetic diversity and population structures in 206 P. vivax clinical samples collected at two time points in two international border areas: the China-Myanmar border (CMB) (n = 50 in 2004 and n = 52 in 2016) and Thailand-Myanmar border (TMB) (n = 50 in 2012 and n = 54 in 2015). Parasites were genotyped using 10 microsatellite markers. Results Despite intensified control efforts, genetic diversity remained high (H E = 0.66–0.86) and was not significantly different among the four populations (P > 0.05). Specifically, H E slightly decreased from 0.76 in 2004 to 0.66 in 2016 at the CMB and increased from 0.80 in 2012 to 0.86 in 2015 at the TMB. The proportions of polyclonal infections varied significantly among the four populations (P < 0.05), and showed substantial decreases from 48.0% in 2004 to 23.7 at the CMB and from 40.0% in 2012 to 30.7% in 2015 at the TMB, with corresponding decreases in the multiplicity of infection. Consistent with the continuous decline of malaria incidence in the GMS over time, there were also increases in multilocus linkage disequilibrium, suggesting more fragmented and increasingly inbred parasite populations. There were considerable genetic differentiation and sub-division among the four tested populations. Temporal genetic differentiation was observed at each site (F ST = 0.081 at the CMB and F ST = 0.133 at the TMB). Various degrees of clustering were evident between the older parasite samples collected in 2004 at the CMB and the ...