Evaluation of the population structure and genetic diversity of Plasmodium falciparum in southern China

Background: Yunnan and Hainan provinces are the two major endemic regions for Plasmodium falciparum malaria in China. However, few studies have investigated the characteristics of this parasite. Therefore, this study aimed to evaluate the genetic diversity and population structure of P. falciparum to predict the geographic origin of falciparum malaria. Methods: Thirteen highly polymorphic microsatellite loci were studied to estimate the genetic diversity and population structure of 425 P. falciparum isolates obtained from blood samples collected from Yunnan and Hainan provinces of South China. The isolates were analysed for genetic diversity, linkage disequilibrium, and population structure. The parasite populations were clustered into two subgroups (i.e., Yunnan and Hainan) and a classification algorithm was used to identify molecular markers for classifying the P. falciparum populations. Results: All 13 microsatellite loci were highly polymorphic, with the number of alleles per locus varying from 5 to 20. The mean expected heterozygosity ( He) in Yunnan and Hainan was 0.766 +/- 0.036 and 0.677 +/- 0.039, respectively, revealing a moderate high level of genetic diversity. Significant linkage disequilibrium was found for some regions of Yunnan (Lazan county and Xishuangbanna region) and Hainan (Dongfang city and Sanya city) province. According to the classification algorithm, a combination of three microsatellites could be used as a discriminatory marker to identify the origin of P. falciparum isolates. Conclusions: The results on the genetic structure of P. falciparum populations from South China provide a basis for developing a genetic marker-based tool to trace the source of the parasite infections and consequently improve malaria control and elimination strategies.