Researchers confirmed a high prevalence of malaria in sites ranging from New York to West Virginia to Louisiana. (Representational Image)
Scientists have discovered the first-ever malaria parasite known to live in a deer species which is the only native malaria parasite found in any mammal in North or South America.
The parasite, Plasmodium odocoilei, infects up to 25 per cent of white-tailed deer along the East Coast of US, researchers said.
Though white-tailed deer diseases have been heavily studied - scientist had not noticed that many have malaria parasites.
"It is a parasite that has been hidden in the most iconic game animal in the US. I just stumbled across it," said Ellen Martinsen from Smithsonian Conservation Biology Institute who led the study.
There is little danger to people from this newly discovered deer malaria, but it underlines the fact that many human health concerns are connected to wider ecological systems - and that understanding the biology of other species is a foundation to both conservation and public health management, researchers said.
They discovered that the deer malaria is widespread - though 'cryptic,' because the parasites occur in very low levels in many of the infected deer.
Using sensitive molecular Polymerase Chain Reaction (PCR) techniques to understand the genetics, researchers confirmed a high prevalence of the disease - between eighteen and twenty-five per cent - in sites ranging from New York to West Virginia to Louisiana.
"The new discovery fundamentally changes our understanding of the distribution and evolutionary history of malaria parasites in mammals," said Ms Martinsen.
The data shows that the deer actually carry two genetic lineages of the malaria parasites - "probably different species," and that the two lineages are substantially different from each other, she said.
This divergence between the two forms of malaria was used by researchers as a kind of molecular clock.
"We can date the evolutionary split between those two lineages to 2.3 to 6 million years ago. Which probably means that when the ancient evolutionary ancestors to white-tailed deer travelled from Eurasia across the Bering Land Bridge to North America in the Miocene, some 4.2 to 5.7 million years ago - malaria came along for the ride," said Ms Martinsen.
"We think malaria is native to the Americas, that it has been here for millions of years," she added.
The findings were published in the journal Science Advances.