Malaria affects millions of people per year. It also infects birds, bats and other mammals. Now, a new study suggests that the mosquito-borne parasite may have its roots in bird hosts, where it spread to bats and eventually to other mammals.
For the new study published in the journal Molecular Phylogenetics and Evolution, Holly Lutz, from Cornell University, and colleagues screened blood samples that were taken from hundreds of East African birds, bats and small mammals for parasites.
When they found malaria, a parasitic single-celled organism that can reproduce in its host's bloodstream, they sequenced its DNA to find mutations in the genetic code.
The differences in the genetic code of malaria revealed how different species of this parasite are related. The researchers then used computer software to know how these different species of malaria evolved and how they are related to each other.
The analysis suggested that malaria originated in bird hosts, from which it spread to other mammals such as bats.
"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," Lutz explained. "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."
Figures from the World Health Organization show that as of December 2015, malaria affects 214 million people.
Initial symptoms of the disease, which include headache, chills, vomiting and fever, often appear at least a week after the patient gets bitten by an infected mosquito. If left untreated, the patient may suffer from more severe illness, which could lead to death.
While the potentially deadly disease is preventable and curable, it continues to be a burden particular in Sub-Saharan Africa, which is home to 88 percent of malaria cases and 90 percent of malaria deaths worldwide.
While the research on the evolution of the malaria parasite does not have direct implication for the treatment of malaria in humans, the researchers said that knowing how malaria evolved may help scientists get a better understanding of how malaria spreads to humans and anticipate its future.
"These results highlight the importance of broad taxonomic sampling when analyzing phylogenetic relationships, and have important implications for our understanding of key host switching events in the history of malaria parasite evolution," the researchers wrote in their study.