The Origins of Human Malaria

We've always believed the origin of the malaria parasite was the chimpanzee and that at some point, mosquitos spread it to humans. But we're now surprised to know, it came from gorillas and made its jump to humans just once which means it was highly successful in adapting to the human host.

Malaria is spread by mosquitoes and there are five species of the parasites which all cause malaria in humans. In two thousand seventeen over two hundred million cases of malaria were recorded.

Until this study, it was believed that the parasite that infects humans, Plasmodium. falciparum, had its closest relative in P. reichenowi which is found in chimpanzees. To see if that's true, scientists used a bank of fecal samples from eighteen hundred chimanzees, eight hundred gorillas, and one hundred bonobos. Researchers were then able to isolate the parasites' mitochondrial DNA sequences.

Next, they created a family tree to view the relationships between the parasites based on their DNA. They found at least nine species of Plasmodium, three unknown before. When compared to human P. falciparum, the most closely related came from western gorillas from Cameroon, the Central African Republic and the Republic of Congo. In fact one was nearly identical to all known human plasmodium sequences.

What we don't know is when the parasite first infected humans and whether gorillas are a source of recurring infections now.