Virus World

The Utah Division of Wildlife Resources (DWR) last week confirmed the first case of chronic wasting disease (CWD) in Payson, located in Utah County in the central part of the state. The confirmed case was 1 of 26 positive CWD cases, including 25 deer and one elk, identified from July 1 to November 28. Most of the cases were from the northeastern part of the state, but Payson is a new area for CWD, DWR officials said. Eighteen of the animals were harvested by hunters, five were found dead, and three were sick animals that were euthanized by the DWR.

Disease appears to be spreading

"We can't accurately compare each year's positive cases to determine how fast the disease is spreading because we sample different areas of the state each year that have different prevalence; alternatively, we compare each unit from year to year," DWR State Wildlife Veterinarian Ginger Stout, DVM, said in a DWR press release. "However, we are finding the disease in new areas, so unfortunately, it does appear to be spreading in Utah." CWD was first detected in a mule deer in northeastern Utah in 2022. A total of 188 mule deer and four elk have tested positive for the disease, which is a fatal neurologic condition found in deer and other cervids. Caused by misfolded proteins called prions, CWD is similar to bovine spongiform encephalopathy ("mad cow" disease). Although no human cases of CWD have been found in Utah or elsewhere, infected cervids can shed prions in urine, feces, and saliva, and transmission may occur through direct contact with an infected animal or indirectly through environmental contamination. Health officials urge people to avoid eating the meat of infected animals and to take precautions when field-dressing or butchering cervids.

Widespread human SARS-CoV-2 infections combined with human-wildlife interactions create the potential for reverse zoonosis from humans to wildlife. We targeted white-tailed deer (Odocoileus virginianus) for serosurveillance based on evidence these deer have ACE2 receptors with high affinity for SARS-CoV-2, are permissive to infection, exhibit sustained viral shedding, can transmit to conspecifics, and can be abundant near urban centers. We evaluated 624 pre- and post-pandemic serum samples from wild deer from four U.S. states for SARS-CoV-2 exposure. Antibodies were detected in 152 samples (40%) from 2021 using a surrogate virus neutralization test. A subset of samples was tested using a SARS-CoV-2 virus neutralization test with high concordance between tests. These data suggest white-tailed deer in the populations assessed have been exposed to SARS-CoV-2.

Preprint available in bioRxiv (July 29, 2021):

 https://doi.org/10.1101/2021.07.29.454326 

Significance

The origin of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing the global coronavirus disease 19 (COVID-19) pandemic, remains a mystery. Current evidence suggests a likely spillover into humans from an animal reservoir. Understanding the host range and identifying animal species that are susceptible to SARS-CoV-2 infection may help to elucidate the origin of the virus and the mechanisms underlying cross-species transmission to humans.

Here we demonstrated that white-tailed deer (Odocoileus virginianus), an animal species in which the angiotensin converting enzyme 2 (ACE2) - the SARS-CoV-2 receptor - shares a high degree of similarity to humans, are highly susceptible to infection. Intranasal inoculation of deer fawns with SARS-CoV-2 resulted in established subclinical viral infection and shedding of infectious virus in nasal secretions. Notably, infected animals(Jan. 14, 2021 transmitted the virus to non-inoculated contact deer. Viral RNA was detected in multiple tissues 21 days post-inoculation (pi). All inoculated and indirect contact animals seroconverted and developed neutralizing antibodies as early as day 7 pi. The work provides important insights into the animal host range of SARS-CoV-2 and identifies white-tailed deer as a susceptible wild animal species to the virus.

Preprint available in bioRxiv (Jan. 14, 2021):

https://doi.org/10.1101/2021.01.13.426628