Scientist are now saying that, Humans may have originally caught malaria from gorillas. This is based on research that examined malaria parasites in great ape feces. It was originally thought that the human malaria parasite split off from a chimpanzee parasite when humans and chimpanzees last had a common ancestor.
Scientists have found that the DNA of malaria from western gorilla was the most similar to human malaria parasites. Scientists had assumed that when the evolutionary tree of humans split off from that of chimpanzees – around five to seven million years ago the malaria parasite had already jumped species. But new evidence suggests human malaria is much newer.
Malaria disease that is caused by a parasite called Plasmodium, this parasite is carried by mosquitoes and is contracted when a person is bit by a mosquito. Over 800,000 people die from malaria each year in Africa.
To study the DNA of malaria in wild apes, you cannot use blood samples. So researchers collected 2,700 samples of faecal material from both western and eastern gorillas as well as from chimpanzees and bonobos.
They sequenced Plasmodium DNA from the faeces with techniques that use a large sample, and drew a genetic family tree to see which parasites were related. ”When we did conventional sequencing, the tree didn’t make any sense, because each sample contained a mixture of parasites,” Said Dr Beatrice Hahn of the University of Birmingham, Alabama.
Researches diluted the DNA so to isolate one parasite’s genome which represented in a single sample From there they amplified the DNA, meaning that they were able to separate the DNA from different species of the parasite much more effectively.
Comparing both methods they found that looking a the larger sampling tree method made much more sense.
They found that the human Plasmodium was not very closely related to chimpanzee Plasmodium,but that the human strain was very closely related to one out of three species of gorilla Plasmodium. Specifically the strain from western gorillas in Central and West Africa.
Researchers discovered that there was more genetic variety in the gorilla parasites than in human parasites.
The study which was published in Nature, and while it provides a lot of answer researchers are going to investigate further. They want to see exactly how different the gorilla and human parasites are and to determine if cross-infection between humans and gorillas may be going on currently.
Members of the research team are hunters and loggers in Cameroon, who spend a lot of time in the forests to determine whether these workers carry malaria parasites from the gorillas, which would suggest that new infections from other species can still happen.
