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Study finds deer infected with Covid-19. It could change the shape of the pandemic.

A white-tailed deer keeps its ears open while grazing in South Hero, Vt.
Rob Swanson
A white-tailed deer keeps its ears open while grazing in South Hero, Vt.

Texas Public Radio's Jerry Clayton recently spoke with Dr. Randall Olsen about a study on deer in Iowa that were infected with Covid-19

Jerry Clayton: A team of scientists at Houston Methodist Hospital teamed up with Penn State researchers to find something surprising that could change the shape of the COVID pandemic. Large segments of the white tailed deer population may be harboring SARS-CoV-2. Dr. Randall Olson is medical director of the Molecular Diagnostics Lab at Houston Methodist. He joins us today. Thanks for being here. Dr. Olson.

Randall Olsen: Oh, thank you.

Clayton: Can you give us an overview of the study?

Olsen: So, we were originally contacted as part of our work doing whole genome sequencing of SARS-CoV-2 isolates from human patients. Our lab has now done more than 70000 viral genomes from human patients, which is by far the most of any lab in the United States. So we were recently contacted by collaborators at Penn State University and the Iowa Department of Natural Resources, who had samples collected for other reasons from white tailed deer. And they were interested to study whether they were potentially infected with COVID and invited us to do some sequencing on those samples.

Clayton: And what did you find?

Olsen: To our surprise, we discovered that about one third of the deer samples that were collected from all across the state of Iowa were positive for SARS-CoV-2 virus RNA, meaning that the deer had the virus in their systems.

Clayton: And how did they get it?

Olsen: That is something that we are continuing to investigate from the genome sequencing. It is very clear that the viral lineages that the deer had contracted were very similar to the one circulating in humans in Iowa. At the same time period. So it's very likely that these came initially from humans or some from humans to some other intermediate source.

Clayton: Now, to your knowledge, have deer been reservoirs of other diseases in history?

Olsen: Well, so we knew from some very small laboratory controlled studies that deer could be infected experimentally with SARS-CoV-2, but we did not know really what was happening in nature. So this was sort of unexpected to find it being so widespread.

Clayton: So if I'm understanding correctly, these deer are transmitting the virus among themselves. What are the chances that they can transmit a virus to a human or a cattle or other animals?

Olsen: So, so that's sort of the next stage in this research project is very clearly that the virus jumped from humans to deer. You know, the risk is concerning that it could further mutate or evolve and deer and then jump back to the humans, whether that would be direct deer to human or through some other intermediate source, such as rodents, deer, mice and so forth. You know, we know from like Lyme disease that deer mice were a intermediate host. So there's a lot for us to learn from that.

Clayton: Does this mean potentially that the SARS-CoV-2 could stay around forever with this reservoir in animals?

Olsen: So, so that's sort of one of the concerns is that even if we become very successful at vaccinating humans, that if there are animal sources that could sort of remain as a reservoir where the virus could continue to mutate and change or potentially jump back into the human population.

Clayton: Is there any interest from the state of Texas to do a similar study here?

Olsen: So the answer is yes, that our study was the first. I know from colleagues across the country that many other states are starting to look at that, including Texas.

See the study here

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Jerry Clayton can be reached at jerry@tpr.org or on Twitter at @jerryclayton.