Americans are being warned to steer clear of squirrels after disturbing images surfaced of the animals with wart-like growths, oozing sores, and swollen faces.

The photos, shared widely on Reddit and Facebook, have left many alarmed. One user wrote, “Any ideas what is going on with this little fella?” after spotting a squirrel with a large mass on its face.

Experts have identified the condition as squirrel pox (or squirrel fibromatosis), a naturally occurring virus that’s more common than people realize.

Wildlife biologist Shevenell Webb explained, “It is naturally occurring and will run its course in time,” but warned people not to approach infected animals:“I would not recommend trying to capture a squirrel that has the virus.” Read more below