Malaria infection harms wild African apes

Malaria is a devastating disease caused by parasites that are transmitted through the bites of infected mosquitoes. In humans, the disease begins with mild symptoms such as fever, headache and chills, but malaria can kill him within 24 hours. For apes, little is known about what malaria is like or how deadly it is.

“We still don’t know enough about symptoms and mortality risk,” said Emily Woblewski, assistant professor of bioanthropology at the University of Washington’s School of Arts and Sciences in St. Louis. They may or may not show fever and other symptoms that may be related to infection, and tracking these symptoms in the wild is very difficult.”

Scientists know that malaria infections are widespread throughout the geographic range of wild chimpanzees and gorillas (they know this because researchers detect parasite DNA in ape feces). ). In fact, African great apes harbor at least 12 different malaria parasite species, seven of which are closely related to human parasites that cause about 95% of human deaths.

But bonobos, a specific kind of ape, have so far escaped infection, except in two places the researchers have examined in the wild. The scientist compared an infected population, in which 38% of bonobos had detectable parasite DNA in their faeces, to uninfected bonobos from his 10 other locations in nature in the Democratic Republic of the Congo. can.

This difference gives researchers an opportunity to try to unravel some basic facts about how malaria affects health and mortality in great apes.

Wroblewski’s new study was published on February 23. Nature Communications, found that in areas where malaria infections were detected, bonobos likely carry a specific variant of the immune gene (Papa-B). closely resembles a human subspecies (HLA-B*53) associated with protection from the development of This suggests that similar immune defense mechanisms may be used in these two species.

“For us, this means that individuals with these protective variants have a selective advantage because they are more likely to survive infection and reproduce, and the frequency of that variant increases,” said Wroblewski.

“This difference in immune characteristics between infected and uninfected populations suggests that bonobos may have increased mortality or increased costs of reproductive success due to infection. “Differences between bonobo populations provide the first evidence, albeit indirectly, that wild great apes are somehow affected by infection.”

pattern of protection

One of Wroblewski’s collaborators on the paper, Beatrice Hahn of the University of Pennsylvania, has documented malaria transmission patterns in great apes over recent decades. Her previous research helped establish that the deadliest human malaria parasite started with a jump from a gorilla.

“Understanding the natural history and transmission patterns of malaria in our relatives is important for measuring future transmission,” Hahn said.

In this study, the DNA used for sequencing was extracted from feces collected after bonobo deposition, thus avoiding handling or other disturbances of wild bonobos.

Scientists were particularly intrigued that the immunogenetic patterns observed in infected bonobos were very similar to those observed in human populations experiencing malaria infections in Africa. .

“This is remarkable because these immune genes evolve very rapidly as they try to keep up with rapidly evolving pathogens,” said Wroblewski. “For this reason, it is extremely rare to observe shared patterns between humans and their closest living relatives.”

She said scientists need to investigate further how this particular immune gene variant protects individuals, both bonobos and humans. Understanding its mechanism could lead to additional sources of human therapy or vaccination.

Since apes are endangered species, it is also important to understand how diseases affect them. Disease is a constant threat to their survival as the pressure from human activities is increasing.

“There are many ways that each host adapts in response to infection, but it’s surprising that both humans and bonobos respond to infection in similar ways,” said Wroblewski.