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Avian Influenza, ‘Bird Flu, linked to deaths of black bear and mountain lion in Colorado


COLORADO (KRDO) -- The highly pathogenic avian influenza (HPAI), commonly known as the bird flu, has now been linked to other animals across the state.

Colorado Parks and Wildlife released a press release on Feb. 9 announcing it's identified several cases of HPAI in free-ranging wildlife. A black bear from Huefano County was affected by the disease in October, a skunk from Weld County tested positive for the disease in November, and a mountain lion that recently died in Gunnison County was confirmed to have the disease.

According to CPW, all three of the confirmed cases showed signs of HPAI before or after death, including neurologic symptoms like seizures or circling, general signs of illness such as weakness or lack of responsiveness to human presence, and organ damage including encephalitis, hepatitis, and pneumonia.

The current strain of HPAI was first confirmed in wild geese in northeast Colorado in March 2022. That went on to kill thousands of wild birds across the country.

Other similar suspected mammalian cases have been detected in the state, confirmatory testing is pending.

The Huerfano County black bear was euthanized on Oct. 8, 2022, by a CPW wildlife officer after he saw it having seizures. Its remains were frozen until the bear was taken to a health lab for testing. A necropsy revealed the bear had signs of HPAI, prompting CPW to test for HPAI.

“The decision to humanely euthanize the animal by our wildlife officer was made following the abnormal behavior and knowledge that numerous infectious diseases cause neurological symptoms,” said CPW Area Wildlife Manager Mike Brown in a press release. “Extremely ill animals have difficulty moving and often act abnormally. While clinical signs of numerous diseases may be observed, diagnostic laboratory testing and necropsy services help determine the actual cause of death.”

In Alaska, a black bear also tested positive for HPAI in October of 2022.

The Gunnison County mountain lion was found dead just outside of city limits on Jan. 15, 2023, in an area where mountain lion activity is commonplace. According to CPW, the mountain lion had necrosis in the liver and bronchointerstitial pneumonia, which have been seen in domestic cats with HPAI, so this also warranted HPAI testing. 

“Similar to many local species, mountain lions move through our communities on a regular basis as they travel between seasonal ranges throughout the year,” said CPW Area Wildlife Manager Brandon Diamond. “It was only a matter of time before the first HPAI case was confirmed in Gunnison County based on known cases in adjacent counties. While this is an interesting case study with the lion, it’s important to point out that HPAI has been documented previously in a variety of mammals from across the country. In Gunnison County, CPW routinely investigates reports of sick and injured wildlife and is always interested in hearing from the public if they encounter something that doesn’t look quite right.”

According to CPW, several mammalian wildlife species have been affected by the current strain of HPAI in the U.S. including skunks, foxes, black bears, bobcats, coyotes, and raccoons. It's even been detected in marine mammals.

CPW believes these mammals likely become infected by feeding on wild birds that are sick or have died of HPAI; however, not every mammal that consumes a sick bird will develop HPAI.

Officials said these recent Colorado cases add to a growing nationwide list of affected wildlife species. Still, CPW said despite the variety of mammalian species susceptible to HPAI, the number of mall cases is currently low.  

Although rare, CPW said HPAI strains can infect people. See the CDC website for more information on protective actions for people.

This link provided by the U.S. Department of Agriculture lists the confirmed wildlife mammalian cases that have tested positive for HPAI to date.

Below are several resources CPW provided regarding HPAI:

For more information on HPAI in Colorado

For information on HPAI in pets

For information on hunting and HPAI

For information on HPAI in wild birds in the United States

For information on HPAI and human health

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