The Origins of African Plasmodium vivax; Insights from Mitochondrial Genome Sequencing

Abstract

Plasmodium vivax, the second most prevalent of the human malaria parasites, is estimated to affect 75 million people annually. It is very rare, however, in west and central Africa, due to the high prevalence of the Duffy negative phenotype in the human population. Due to its rarity in Africa, previous studies on the phylogeny of world-wide P. vivax have suffered from insufficient samples of African parasites. Here we compare the mitochondrial sequence diversity of parasites from Africa with those from other areas of the world, in order to investigate the origin of present-day African P. vivax. Mitochondrial genome sequencing revealed relatively little polymorphism within the African population compared to parasites from the rest of the world. This, combined with sequence similarity with parasites from India, suggests that the present day African P. vivax population in humans may have been introduced relatively recently from the Indian subcontinent. Haplotype network analysis also raises the possibility that parasites currently found in Africa and South America may be the closest extant relatives of the ancestors of the current world population. Lines of evidence are adduced that this ancestral population may be from an ancient stock of P. vivax in Africa.

Diversity, host switching and evolution of Plasmodium vivax infecting African great apes

“…This model should translate into: (i) a decrease of genetic diversity from Asia to Africa in the human P. vivax clade; (ii) a global lower genetic diversity in the human P. vivax clade compared with the sylvatic one based on the fact that, in this scenario, the human clade originated from a small P. vivax Asian population; and (iii) the coexistence of two divergent clades in Africa. Regarding point i, some worldwide population genetic data are consistent with this expectation (11). For point ii, all sequences (mitochondrial, 18S and Csp) displayed consistent genetic patterns (Table 1).…”

“…Blood tests showed thrombocytopenia (platelet count, 105 Giga/L), no anemia Network was built using 226 P. vivax sequences (218 previously published (3,11,29), and eight samples from this work). (B) The 18S gene.…”

“…vivax is considered to be virtually absent in humans in West and Central Africa, where more than 95% of the human population is supposed to be resistant to it because of the absence of the Duffy antigen (Duffy negativity) on the surface of their red blood cells (6). However, there are several reports of Duffy positive travelers returning from these regions of the world infected with P. vivax (7)(8)(9)(10) and other studies have reported findings that suggest a possible transmission of the parasite in this region (11,12). Several hypotheses have been proposed to account for this apparent paradox.…”

Using Mitochondrial Genome Sequences to Track the Origin of Imported Plasmodium vivax Infections Diagnosed in the United States

“…Except for three sequences deposited by Cox-Singh and Lau in 2008, all sequence data had been previously published. [23][24][25][26] To augment the number of samples from the Americas in the database, we used the methods described above to amplify and sequence the complete mitochondrial genome of seven additional P. vivax isolates collected between 2010 and 2012 in Remansinho, a rural community in northwestern Brazil, 27 and six isolates collected between 2007 and 2008 as part of routine surveillance activities across three provinces (Eastern Panama, Darien, and Bocas del Toro) of Panama, Central America (GenBank accession numbers KF668430-KF668442).…”

“…P. vivax populations from Africa and India display extensive polymorphism and genetic substructure, which does not necessarily correspond to sampling locations. 26,33 A very dense sampling of these populations will be required for a more accurate geographic tracking of imported infections from Africa and India.…”