After warnings about “zombie rabbits,” a new wave of panic has emerged as photos and videos of squirrels with oozing sores, disfigured faces, and wart-like lumps spread online. Once seen as harmless backyard acrobats, the animals are now leaving many horrified by their grotesque appearance.

One Reddit user shared a photo in late July, admitting they first thought the squirrel “had been eating something,” only to realize the mass was attached to its face. Experts quickly identified the culprit: squirrel pox, also known as squirrel fibromatosis. The virus is naturally occurring and more common than many people realize.

Experts confirm the disease, urge caution

Cases have been reported from Maine to Virginia. Wildlife biologist Shevenell Webb from the Maine Department of Inland Fisheries and Wildlife explained that the condition usually “runs its course” but warned the public not to approach infected animals.

“It’s like when you get a large concentration of people,” Webb said, comparing the spread at feeders to human germs in crowded places. While the growths are disturbing, most squirrels survive unless tumors affect vital organs or block their vision or ability to eat. “For the most part, squirrels with squirrel pox are just really ugly to look at,” Webb added.

At Evelyn’s Wildlife Refuge, staff noted that some lumps are caused not by pox but by botfly larvae burrowing under the skin, another reason for people to avoid handling sick-looking squirrels. Only trained rehabilitators or vets should intervene.