‘Mutant deer’ with bubble-like skin growths spark concern in US

Photos of deer with dark, bubble-like growths on their skin have spread online, prompting fears of a new outbreak. But experts say the condition, known as deer fibroma, is caused by a virus and poses no risk to humans.

Deer with strange lumps on their faces and bodies have recently been spotted in Pennsylvania and Wisconsin. Concerned residents shared photos on Reddit, speculating whether the animals were suffering from tumors, infections, or even prion diseases.

The unusual appearance — warty growths that resemble “flesh bubbles” — led to questions about whether this could signal a new wildlife epidemic.

Deer fibroma

According to state wildlife agencies, the condition is deer fibroma, a skin disease caused by a papillomavirus unique to deer. The Maine Department of Inland Fisheries and Wildlife describes the growths as firm, dark, hairless, and often rough or fissured in appearance.

Most deer develop only a few small fibromas, but some animals experience more widespread cases. While the lumps look alarming, experts stress that the disease is not contagious to humans, pets, or livestock.

How the virus spreads

Wildlife veterinarian Dr. Kristin Mansfield told FOX13 that deer fibroma spreads through direct contact, often when deer gather at feeding sites or use the same rubbing posts.

“These are just like warts in humans,” she explained. “They may cause some itching, but otherwise they don’t harm the deer.”

For hunters, the condition does not affect the safety of venison. The Washington Department of Fish and Wildlife notes the virus remains in the skin, and the meat is still safe to eat once the growths are removed.

There is no treatment for wild deer, but most animals’ immune systems naturally suppress the virus, causing the growths to shrink over time. In rare cases where fibromas block a deer’s vision, movement, or ability to eat, wildlife officials may consider euthanasia.

Experts suggest two main reasons: changing climates and increased social media attention.

Warmer weather allows ticks and mosquitoes, which help spread diseases, to thrive in regions where they were once less common. Dr. Omer Awan of the University of Maryland School of Medicine told The Daily Mail that illnesses like Lyme disease are now appearing in new areas, including parts of southern Canada and northern U.S. states.

At the same time, people are more likely to photograph and share unusual sightings of animals online, fueling wider awareness of conditions like deer fibroma.

Despite its unsettling appearance, deer fibroma is not considered dangerous to humans. The greater concern comes from ticks carried by deer, which can transmit Lyme disease and other illnesses in affected communities.

For now, experts say the best approach is to leave infected deer alone and allow nature to take its course.