Ten raccoons in the past three years have been found on the West Coast with a deadly brain cancer, and scientists are linking the animals’ deaths to a virus they had never seen before.
While typically elusive and nocturnal, the infected raccoons were seen approaching humans, meandering around during the day, and even passing out. Once the raccoons died, veterinarians conducted autopsies and were surprised to find tumors—a rare occurrence in raccoons—in their brains.
Researchers also found what they determined to be the likely culprit in the raccoons’ death: a polyomavirus. Variations of this virus are known to cause tumors in birds and mice and a rare kind of skin cancer in humans, but the raccoon polyomavirus was one scientists didn’t recognize.