Researcher finds first-ever native North American malaria strand

One researcher’s attempt to discover a strain of malaria that could infect birds has led to the discovery of a parasite that infects white-tailed deer, making it the first parasite ever found to live in a deer species and the first found in any North or South American mammal.

Ellen Martinsen, a research associate at the Smithsonian’s Conservation Biology Institute and adjunct faculty in the University of Vermont’s biology department, and her colleagues had been collecting mosquitoes at the Smithsonian’s National Zoo two years ago when they discovered a unique DNA profile from parasites in those insects that they were unable to identify.

The parasite they discovered, Plasmodium odocoilei, is believed to infect up to one-fourth of white-tailed deer living along the east coast of the United States, the researchers reported in a new study published in the February 5 edition of the journal Science Advances.

“You never know what you’re going to find when you’re out in nature–and you look,” Martinsen said last week in a statement. “It’s a parasite that has been hidden in the most iconic game animal in the United States. I just stumbled across it.” She added that while malaria is widespread in the deer, it is “cryptic: in that infected animals appear to have very low levels of the parasite.

Parasite found to affect up to 25 percent of East Coast deer

Martinsen, who conducted the research with University of Vermont biologist Joseph Schall and colleagues from the Smithsonian Conservation Biology Institute, the University of Wisconsin-Milwaukee, the University of Georgia, the National Park Service and the American Museum of Natural History, noted that the parasite is unlikely to pose a direct health risk to people.

That said, they explained that the discovery highlights the fact that some human health concerns are connected to larger-scale ecological systems, and that obtaining a better understanding of the biology of other types of creatures can bolster both conservation and global health efforts.

In light of recent concerns over the Zika virus, Schall said that the discovery of this new parasite is “a reminder of the importance of parasite surveys and basic natural history.” The study authors found that the disease affected between 18 and 25 percent of deer living in areas from New York to West Virginia and even as far south as Louisiana.

Martinsen said that the discovery fundamentally alters our understanding of the distribution and the evolutionary background of malaria parasites in mammals. While some experts wondered if deer malaria could have been transmitted from people or other animals, the new study found that deer actually carry two different genetic lineages of the parasites. These lineages, which are most likely different species, are substantially different from one another, the researchers said.

She went on to note that the evolutionary split between these two lineages took place between 2.3 and 6.0 million years ago, meaning that malaria likely arrived in North America from Europe when the evolutionary ancestors to the white-tailed deer crossed the Bering Land Bridge during the Miocene epoch between 4.2 and 5.7 million years ago.

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