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Do Frankenstein bunnies really exist? Social media reports have shown rabbits with growths that resemble tentacles or horns in Colorado and other states. But wildlife experts say humans shouldn't be alarmed.

The growths are an infection called the Shope papillomavirus, named after Richard E. Shope, who discovered it in 1933, according to the National Library of Medicine. The disease is also known as cottontail rabbit papillomavirus.

People have been fascinated by this disease for hundreds of years. According to The Associated Press, the "jackalope" myth was probably influenced by rabbit papillomavirus. The jackalope is a fictional animal that originated in North America and is characterized by a rabbit with horns or antlers.

Despite the rabbits' bizarre-looking horns, experts say, the condition is harmless.

How does the virus affect rabbits?

The hornlike growths on the rabbits are wart-like tumors caused by the Shope papillomavirus, according to the Colorado Parks and Wildlife. The growths generally don't trouble the cottontails unless they form near their mouths, which can make it difficult for them to eat or drink.

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Where have zombie horned rabbits been reported?

Scientists have known about the virus in the Midwest since the 1930s, but the rabbit papillomavirus has been detected in rabbits in a number of states, including Colorado, Iowa, Kansas, Minnesota, Nebraska and Washington, according to social media reports.

How does the Shope papillomavirus spread?

Rabbits most commonly contract the hornlike growths of Shope papillomavirus after being bitten by infected insects such as fleas, ticks and mosquitoes. After feeding on an infected wild rabbit, the insects spread the virus to other rabbits. The virus also can spread by direct contact between rabbits through body fluids such as feces, saliva and urine.

According to Scientific American, papillomavirus may also cause squamous cell cancer in rabbits, which can be deadly to the animals. Infections are more risky in domestic rabbits and should be treated by veterinarians, according to Colorado Parks and Wildlife.

Is the rabbit virus dangerous to humans?

Papillomaviruses can infect a wide range of species, including fish, reptiles, birds and humans, but the vast majority are specific to certain species, according to an article in the National Library of Medicine in 2024.

The cottontail rabbit papillomavirus is specific to rabbits and cannot infect other species, according to Colorado Parks and Wildlife. But the virus can be transmitted to domestic rabbits, especially those housed outdoors, where they may come into contact with wild rabbits or biting insects.

CONTRIBUTING N'dea Yancy-Bragg and Melina Khan

This story was updated to add new information.

This article originally appeared on USA TODAY: Do 'Frankenstein rabbits' exist? What to know about this strange disease

Reporting by Janet Loehrke, USA TODAY / USA TODAY

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