27 Jul Study Raises Concerns About Potential for Deer to Serve as Reservoir for SARS-CoV-2

MedicalResearch.com Interview with:

Dr. Thomas Deliberto, PhD, DVM, APHIS
Wildlife Services One Health Coordinator

MedicalResearch.com: What is the background for this study?

Response: In 2021, USDA launched a pilot study to investigate exposure of wild white-tailed deer (Odocoileus virginianus) to SARS-CoV-2, a zoonotic virus and the virus that causes COVID-19. Researchers found that 40% of the blood samples tested had SARS-CoV-2 antibodies. This initial study suggested that SARS-CoV-2 could be transmitted from humans to deer, and that deer could potentially serve as a reservoir for the virus.

To better understand the transmission of SARS-CoV-2 in white-tailed deer, a team of researchers conducted a larger study to collect and analyze respiratory samples from free-ranging white-tailed deer in the United States.  The study identified SARS-CoV-2 sequences in white-tailed deer across nearly half of the states in the U.S. The researchers also found that deer could be infected with multiple SARS-CoV-2 lineages, and that these lineages could be transmitted from deer to deer.

In addition, the researchers found three cases of potential virus transmission from white-tailed deer back to humans.  This raises concerns about the potential for the virus to continue to evolve in an animal reservoir, and the possibility of future spillover events.

MedicalResearch.com: What are the main findings? How is the virus transmitted between deer and humans?

Response:  The researchers identified 109 instances of transmission of SARS-CoV-2 from humans to deer in 22 States.  Once the virus infected deer, it was able to spread within those populations.    Thirty-four distinct SARS-CoV-2 lineages were detected in deer.  Three cases of potential transmission from deer back to humans were identified based on the genetic analyses of SARS-CoV-2 sequences available.

This study was not designed to determine the transmission routes of the virus between people and deer.  However, given the number of spillover events across the broad range of white-tailed deer, the researchers believe that multiple routes of transmission were likely. Evidence for potential deer-to-human transmissions was determined by focusing on specific mutations that appeared to be unique to a virus circulating in white-tailed deer populations. By looking at the 14 million human SARS-CoV-2 sequences in publicly available databases, researchers found three cases of potential spillover from white-tailed deer back to humans.

These findings suggest that white-tailed deer could potentially serve as a reservoir for SARS-CoV-2, and that the virus could be transmitted between deer and humans. This raises concerns about the potential for the virus to continue to evolve in deer, and the possibility of future transmission events from deer to humans.

It is important to note that the study did not find any evidence that SARS-CoV-2 is easily transmitted from deer to humans. However, the researchers believe that it is important to continue to monitor the situation, as the virus could potentially adapt to become more easily transmittable. 

MedicalResearch.com: What should readers take away from your report? 

• It is important to remember that while experts are still learning about SARS-CoV-2 in animals, there is no evidence that animals play a significant role in spreading the virus to humans.
• SARS-CoV-2 spilled over from humans to white-tailed deer in nearly half of the U.S. states.
• Deer can be infected with multiple SARS-CoV-2 lineages, and these lineages can be transmitted from deer to deer.
• There have been three cases of potential transmission from deer back to humans.
• It is important to note that the study did not find any evidence that SARS-CoV-2 is easily transmitted from deer to humans.
• The researchers believe that it is important to continue to monitor the situation, as the SARS-CoV-2 virus could potentially adapt to become more easily transmitted between humans and deer.

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

• Continued surveillance of SARS-CoV-2 in white-tailed deer will help to track the spread of the virus in deer populations, and to identify any new lineages that emerge.
• Additional studies are needed to determine the routes of transmission of SARS-CoV-2 between deer and humans. This will help to better understand how the virus is spread, and to develop strategies to prevent potential transmission.
• Studies to investigate the potential for SARS-CoV-2 to evolve in deer will help assess the risk of the virus becoming more easily transmitted from deer to humans.
• To ascertain whether an animal species serves as a reservoir by maintaining and spreading the virus, it is necessary to implement long-term surveillance programs that monitor the prevalence and behavior of the pathogens within the animal population over an extended period. Study findings reveal that SARS-CoV-2 viruses have indeed been transmitted among the deer population. Ongoing studies focusing on SARS-CoV-2 in deer aim to determine if these viruses can maintain a persistent presence within the deer population.

These research studies are important to help us better understand the potential risks of SARS-CoV-2 in white-tailed deer, and to develop strategies to mitigate these risks.

MedicalResearch.com: Is there anything else you would like to add? Any disclosures?

APHIS and its partners have published four scientific manuscripts based on Year 1 results.

1. The journal Nature Communications published, “Transmission of SARS-CoV-2 in free-ranging white-tailed deer in the United States,” by APHIS, the University of Missouri and the Centers for Disease Control and Prevention (CDC). This study found evidence that SCV-2 was transmitted from humans to deer, circulated in white-tailed deer populations, and potentially transmitted back into humans.
2. Biorxiv published APHIS’ pre-print paper, “SARS-CoV-2 Occurrence in white-tailed deer throughout their range in the conterminous U.S.”. This paper releases national information about SCV-2 detected in cervid populations.
3. Research Square published the pre-print paper, “Accelerated evolution of SARS-CoV-2 in free-ranging white-tailed deer” by The University of Ohio and its partners including APHIS. This research shows SCV-2 was transmitted from humans to white-tailed deer in Ohio, that the viruses repeatedly mutated in deer, and that SCV-2 was evolving faster in deer compared to humans.
4. Research Square published the APHIS pre-print, “Epidemiological dynamics of SARS-CoV-2 in white-tailed deer.” This research shows that male deer have higher positivity rates than female deer, and infection is higher in counties with higher human population densities.

Learn more about all the APHIS research projects on zoonotic diseases in animals by visiting our Agency’s One Health page.

Citation:

Feng, A., Bevins, S., Chandler, J. et al. Transmission of SARS-CoV-2 in free-ranging white-tailed deer in the United States. Nat Commun 14, 4078 (2023). https://doi.org/10.1038/s41467-023-39782-x

https://www.nature.com/articles/s41467-023-39782-x

The information on MedicalResearch.com is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.

Last Updated on August 3, 2023 by Marie Benz