A new study published this week found the first evidence of the rustrela virus in a cougar in Douglas County.
DENVER — A new study published in the journal Emerging Infectious Diseases reports the first discovery of a deadly virus in a mountain lion in North America.
In May 2023, Colorado Parks and Wildlife euthanized a sick cougar in Douglas County because it had difficulty using its back legs.
Through analysis of the animal’s tissues, researchers discovered the presence of the rustrela virus, which has been identified as the cause of the vertigo disease. The disease is a fatal neurological syndrome that affects domestic cats, according to Colorado Parks and Wildlife.
Former Colorado Parks and Wildlife Pathologist Dr. Karen Fox was the lead author of the paper. Fox said the diagnosis was challenging and confirmation was possible only through collaboration with researchers in Germany.
Fox said it is not known how widespread the virus is among domestic cats or wild animals. In Europe, the virus is found not only in cats but also in other species, including rodents, marsupials and a donkey, according to Colorado Parks and Wildlife.
“Now that we know what we’re looking for, it should be easier to find new cases when they occur,” Fox said. “With continued collaboration, we plan to learn what we can from our colleagues in Europe as we continue to look for new cases of vertigo here in Colorado.”
Colorado State University and Colorado Parks and Wildlife veterinarians will be closely monitoring for new cases. Anyone who sees a mountain lion acting abnormally, staggering or having difficulty walking should contact their local Colorado Parks and Wildlife office.