Out of Africa: origins and evolution of the human malaria parasites Plasmodium falciparum and Plasmodium vivax

Abstract

Plasmodium falciparum and Plasmodium vivax account for more than 95% of all human malaria infections, and thus pose a serious public health challenge. To control and potentially eliminate these pathogens, it is important to understand their origins and evolutionary history. Until recently, it was widely believed that P. falciparum had co-evolved with humans (and our ancestors) over millions of years, while P. vivax was assumed to have emerged in southeastern Asia following the cross-species transmission of a parasite from a macaque. However, the discovery of a multitude of Plasmodium spp. in chimpanzees and gorillas has refuted these theories and instead revealed that both P. falciparum and P. vivax evolved from parasites infecting wild-living African apes. It is now clear that P. falciparum resulted from a recent cross-species transmission of a parasite from a gorilla, while P. vivax emerged from an ancestral stock of parasites that infected chimpanzees, gorillas and humans in Africa, until the spread of the protective Duffy-negative mutation eliminated P. vivax from human populations there. Although many questions remain concerning the biology and zoonotic potential of the P. falciparum- and P. vivax-like parasites infecting apes, comparative genomics, coupled with functional parasite and vector studies, are likely to yield new insights into ape Plasmodium transmission and pathogenesis that are relevant to the treatment and prevention of human malaria.

Marked variation in prevalence of malaria-protective human genetic polymorphisms across Uganda

“…A number of dating studies suggest that sickle hemoglobin and G6PD deficiency arose within the last few thousand years (Hedrick, 2011). The marked differences in prevalences of malaria-protective polymorphisms between ethnic groups are consistent with our recent understanding of the evolution of P. falciparum , with the appreciation that this parasite crossed from gorillas to humans quite recently, probably within the last 10,000 years (Loy et al, 2017). Thus, it is plausible that modern differences in the prevalence of malaria-protective human genetic polymorphisms are due to differences in malaria risk over the last few thousand years.…”

Signatures of competition and strain structure within the major blood‐stage antigen of Plasmodium falciparum in a local community in Ghana

“…P. falciparum ‐ like parasites have been circulating in primates for at least 6–10 million years (Prugnolle et al., ) and P. falciparum is well adapted to its human host (Loy et al., ). The vast majority of infections do not even cause disease symptoms (>99%), and despite decades of intensive control efforts, P. falciparum continues to thrive within human populations worldwide, causing over 200 million malaria cases per year worldwide (WHO, ).…”

Evidence of unique genetic diversity in Aspergillus fumigatus isolates from Cameroon

“…However, at present, very little is known about the genetic diversity of African populations of A. fumigatus . Elucidating the genetic diversity in African populations of A. fumigatus might be of critical importance given the high number of AIDS‐related immunocompromised patients, and that several human pathogens have been previously suggested to have evolved out of Africa . Interestingly, West African isolates of Aspergillus flavus, a species closely related to A. fumigatus , are known to be geographically and physiologically divergent from those in North America .…”