Malaria parasites hide in U.S. white-tailed deer according to the latest study published in the Science Advances journal. Ellen Martinsen and Rob Fleischer with the National Zoo made this discovery after sampling white-tailed deer populations in 45 counties spanning their habitats.
As per the findings of the study, 18 percent of the white-tailed deer in eastern U.S. carry the Plasmodium odocoilei parasite which causes malaria. In addition, 25 percent of the white-tailed deer in states such as West Virginia and Virginia carry the Plasmodium odocoilei.
Martinsen, Fleischer and colleagues with the Smithsonian Conservation Biology Institute, the American Museum of Natural History and others believe the malaria causing parasite has been hiding in plain sight, possibly for hundreds of years. However, this is the first time the malaria causing parasite has been found in such large proportions in any mammal population of North America.
The first samples which indicated the presence of Plasmodium odocoilei were collected from mosquitoes. A simple tracing process led the research team to white-tailed deer populations. To make sure this is the only mammal population which carries the malaria causing parasite, the researchers also took tissue and blood samples from elk populations and other ungulate species.
After a thorough analysis, the researchers were surprised to find that malaria parasites hide in U.S. white-tailed deers only.
The only time a similar finding surfaced was in 1967. At the time, a singly Texas white-tailed deer was found to carry the malaria causing parasite. However, this specimen suffered a spleen removal which allowed pathogens to manifest for further analysis.
The recent study is the only one which found Plasmodium odocoilei in such large white-tail deer population samples. While the effect of the malaria causing parasite on the mammal populations is not yet understood, the research team believes it has been hiding in plain sight for a long time. However, as the malaria parasite is found as such low concentrations in the blood, it may go undetected for a long while, depending on the method of analysis.
The Plasmodium parasites are carried by mosquitoes. When these pests feed on a mammal, it most certainly becomes a host infected with the protozoans. From here on, a never ending cycle occurs. Other mosquitoes pick it up and further infect other mammals, in this case white-tailed deer.
The research team found that with the white-tailed deer the Plasmodium odocoilei only occurs once for every 65,000 red blood cells. This could be a possible explanation as to how it went undetected for so long. It’s also good news for the white-tailed deer. Classic symptoms of malaria infection do not occur.
While analyzing some of the samples, the researchers found the signature of a second Plasmodium species. However, the parasite could not be physically detected with any of the specimens.
Overall, there are five malaria causing parasites infecting humans. 600,000 people die annually due to malaria infection and another 200 million are sickened. However, there is no risk for the malaria parasite to be transmitted from the white-tailed deer to humans.
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