What is the origin of plasmodium

Malaria came from the gorilla

The malaria pathogen Plasmodium falciparum originally comes from the gorillas and has spread from them to humans. This is shown by a comparative genetic study of pathogen strains in various great ape species that has now been published in “Nature”. It also invalidates previous assumptions that the chimpanzees were the original host of Plasmodium falciparum. However, it is still unclear when the decisive change in species took place.

Hundreds of millions of people develop malaria every year around the world. The mosquito-borne tropical disease causes more than a million deaths each year. Of the five known malaria pathogens, Plasmodium falciparum is the most widespread and deadliest. Although some progress has now been made in treatment and prevention, the origin and natural reservoirs of the malaria pathogens are still unclear.

What kind of monkey was the original host?

For a long time, the species Plasmodium reichowi, discovered in chimpanzees, was considered its closest relative and gave rise to the assumption that the human variant developed at the same time as the separation of humans and the chimpanzee line more than five million years ago. However, within the last year closely related strains have also been discovered in gorillas and bonobos, so that each of these monkey species can be considered as the original reservoir of the malaria pathogen. Now an international team of researchers led by Beatrice Hahn from the University of Alabama has clarified this question.

Plasmodium in all great ape species

For their study, the scientists collected more than 3,000 fecal samples from wild African great apes, including gorillas, chimpanzees and bonobos. Samples were screened for Plasmodium species and samples from malaria infected monkeys were selected for further analysis. From these, the researchers isolated the genome of the Plasmodium pathogen and determined its type and variant by analyzing the DNA. The evaluation initially confirmed that both chimpanzees and gorillas are natural reservoirs for a total of at least nine different species of Plasmodium.

The study graces the cover of "Nature" © Nature

Human tribe comes from the gorilla

But only in one species of monkey did the genetic signatures match the Plasmodium variant common in humans. "All currently available human Plasmodium falciparum sequences appear as a single line in the G1 strain of gorilla parasites," the researchers explain in their "Nature" article. “This suggests that the human Plasmodium falciparum comes from the gorilla, not the chimpanzee, bonobo or our human ancestors. And it shows that all known human tribes could emerge from a single species change event. "

Time of species change still unclear

According to this, the malaria pathogen must have jumped from one organism to the other at some point in an area where gorillas and humans lived together and then adapted to humans as hosts. "However, it is still unclear when the gorilla variant of P. falciparum passed into the human population and whether today's ape populations are still a source of human infections."

(Nature, 23.09.2010 - NPO)

September 23, 2010