Deer across the United States are developing unusual tumour-like growths, leaving wildlife experts and observers concerned. The condition, known as deer cutaneous fibroma—or more commonly “deer warts”—has been increasingly reported over the past two months in states from New York to Pennsylvania to Wisconsin.
The growths, which can look like large warts or bubbles, typically appear on a deer’s face, neck, or legs. Wildlife officials say the disease is caused by a papillomavirus that spreads through deer populations nationwide, and sightings have surged this summer.
“Papillomas are most frequently seen during the late summer and into the fall, probably due to increased biting insect activity during this time of year,” explained the Washington Department of Fish and Wildlife.
Dr. Omer Awan of the University of Maryland School of Medicine told Daily Mail, “These temperature changes are resulting in diseases that were never endemic in certain areas to become endemic.”
What are deer warts?
The virus spreads mainly through biting insects such as mosquitoes and ticks, which carry blood from an infected deer to a healthy one. Warmer months—particularly spring and early fall—create ideal conditions for these insects, making transmission more likely.
The growths can vary widely, from small pea-sized lumps to masses as large as a football. They are often gray, black, or flesh-colored, typically without hair. While their appearance can be disturbing, the condition is usually not fatal.
In most cases, a deer’s immune system eventually eliminates the virus, causing the warts to shrink and disappear within months. However, when growths become very large or infected with bacteria, they can interfere with the animal’s ability to see or eat.
Wildlife veterinarian Dr. Kristin Mansfield told FOX13, “Deer can spread the virus if they share the same feeding areas, sleeping spot, or rubbing posts, usually a tree males use to mark their territory during mating season.” She emphasized that the virus does not affect humans or other animals, as it is specific to deer.
Scientists have studied deer warts since the 1950s, but the condition has become more visible in recent years—partly because of climate change expanding the disease’s range, and partly due to social media making sightings more widely shared.
