White-tailed deer in the United States may have transmitted SARS-CoV-2 back to humans, according to a recent study published in Nature Communications. The researchers found that the virus was transmitted from humans to deer over 100 times, mutated within the deer population, and potentially transmitted back to humans in three cases.
The study collected thousands of respiratory samples from free-ranging white-tailed deer across 26 states and Washington, D.C. Between November 2021 and April 2022, the researchers discovered detectable SARS-CoV-2 in 944 of the collected samples. Further testing and analysis identified 34 lineages of SARS-CoV-2 belonging to various variants, including B.1, alpha, gamma, delta, and omicron.
Interestingly, the researchers found that 238 samples could be grouped into 109 clusters that also contained human SARS-CoV-2 viruses. This suggested that the virus had spilled over from humans to deer on multiple occasions. Moreover, the study uncovered 39 cases of subsequent deer-to-deer transmission and three potential cases of spillover from white-tailed deer back to humans.
The implications of these findings are significant. The researchers argue that white-tailed deer could serve as a reservoir for SARS-CoV-2, posing zoonotic risks to humans. They also highlight the potential of mutated SARS-CoV-2 viruses circulating among deer to undermine the effectiveness of pre-existing human immunity acquired from previous infections or vaccinations.
It’s worth noting that this is not the first report of humans contracting SARS-CoV-2 from deer. Previous evidence of transmission from white-tailed deer to humans was documented in Canada. The emergence and rapid evolution of SARS-CoV-2 have resulted in infections in a wide range of animals, both wild and domestic, such as mink, cats, dogs, and lions. While uncommon, transmission from animals to humans has been observed in farmed mink, domestic cats, and now white-tailed deer.
The U.S. Animal and Plant Health Inspection Service (APHIS) has emphasized that there is currently no evidence indicating animals play a significant role in spreading SARS-CoV-2 to humans. However, ongoing efforts are needed to better understand the relationship between SARS-CoV-2 and animals to ensure wildlife conservation and protect public health.
The findings from this study shed light on the complex dynamics between humans and animals in the transmission of SARS-CoV-2. Understanding these dynamics is crucial for devising effective strategies to control and prevent future outbreaks. Further research is necessary to fully comprehend the risks posed by SARS-CoV-2 circulation in wildlife and to develop comprehensive One Health approaches.
In conclusion, white-tailed deer in the U.S. have been identified as a potential reservoir for SARS-CoV-2, with evidence suggesting transmission between humans and deer and subsequent transmission back to humans. These findings emphasize the need for ongoing research to better understand the risks associated with SARS-CoV-2 in animals and to protect both wildlife and public health.
