While malaria affects almost 500 million people each year, there are various species of the malaria parasite that can affect other animals, such as birds, bats and other mammals. A new study by the Field Museum of Natural History sheds light on the evolution of these unique malaria species in an attempt to further our understanding of the origins of human malaria.
"We can't begin to understand how malaria spread to humans until we understand its evolutionary history," said Holly Lutz, lead author of the study. "In learning about its past, we may be better able to understand the effects it has on us."
In order to better understand the different malaria species, Lutz and her team collected blood samples from hundreds of East African birds, bats and other mammals and examined them for parasites. After pinpointing malaria, they sampled the DNA of the parasites and sequenced it in order to reveal the mutations in the genetic code tied to malaria. Using this data, the team was able to determine the relationship between different malaria species.
The team used large samples and made sure to take DNA for a variety of species of bats and birds in order to create the most complete evolutionary picture of malaria as possible.
"Trying to determine the evolutionary history of malaria from just a few specimens would be like trying to reconstruct the bird family tree when you only know about eagles and canaries," Lutz said. "There's still more to discover, but this is the most complete analysis of its kind for malaria to date."
The results revealed that that malaria parasite originated in bird hosts and then made its way to bats, followed by other mammals. However, Lutz stresses that bats are not responsible for this process.
"It's not that bats are spreading malaria - we get different species of malaria than they do, and we can't get it from them," she said. "Instead, by looking at patterns of mutations in the DNA of the different malaria species, we're able to see when it branched off from one host group into another. It started out as a parasite in birds, and then it evolved to colonize bats, and from there, it's evolved to affect other mammals."
The team hopes that their findings will help scientists better understand how malaria evolves in order to better treat the devastating disease.
"Malaria is notoriously adaptive to treatment, and its DNA holds a host of secrets about how it's able to change and evolve," Lutz said. "Having a better understanding of its evolutionary history could help scientists anticipate its future."
The findings were published in the March 12 issue of Molecular Phylogenetics and Evolution.
