Why ‘Zombie Squirrels’ Have Been Appearing In The U.S. And Canada

The concept of “zombie squirrels” might sound a bit unusual to you. However, that is the term that has been used to describe the peculiar sightings in the U.S. and Canada— squirrels with abnormal, sometimes bleeding, lumps all over their bodies. These lumps can give them a resemblance to the characters seen on the TV series Walking Dead—the undead ones without speaking roles, that is. Nonetheless, these squirrels are not actually undead. They are very much alive but likely suffering from a condition known as squirrel fibromatosis.

Zombie Squirrels Are Actually Squirrels With Tumors

The condition is termed fibromatosis because the lumps are tumors known as fibromas. A fibroma is a benign tumor composed of fibrous connective tissue. These tumors can vary in size from a few millimeters to 25 millimeters in diameter. The impact of these growths depends on their location. When these tumors are only on the squirrel’s skin, they may not have significant consequences, apart from potentially affecting the squirrel’s attractiveness to potential mates, assuming other squirrels are as superficial as humans.

However, complications can arise when the tumors affect vital structures. For instance, tumors near the eyes can impact the squirrel’s vision. Things can escalate when the tumors spread internally to organs like the lungs, liver, kidneys, and lymph nodes. This can lead to blockages, organ dysfunction, and even fatality. Another concern is the potential for these lumps to become infected by various microorganisms beyond the initial infecting agent that caused the fibromatosis.

This disease is not a recent occurrence. Squirrels with this condition have been observed as early as 2023. It’s just that for some reason, more individuals have started noticing these zombie squirrels recently and discussing them on social media platforms. And in today’s world, things may not seem real until they have been shared on social media, right? Here is an example of a recent Facebook post showcasing these unusual lumps:

Zombie Squirrels Result From Infection By A Virus

While news of these zombie squirrels may have spread like wildfire on social media, there is another viral aspect to this disease— its etiology. Infection with a virus called leporipoxvirus is responsible for these tumors. This virus belongs to the poxvirus group, which is why squirrel fibromatosis is also referred to as squirrel pox.

Squirrels can contract this virus through mosquito bites from species like Aedes aegypti and Anopheles quadrimaculatus, or from fleas carrying the virus. An infected squirrel can also transmit the virus to another squirrel through direct physical contact. Tumors typically develop at the site of virus transmission, whether it was via an insect bite or squirrel-to-squirrel contact.

Is There A Treatment For Zombie Squirrels?

Regrettably, there is currently no known treatment for this condition. However, in less severe cases, the lesions may regress over time, leading to full recovery for the squirrels. Additionally, there is no evidence to suggest that this disease is impacting the population numbers of grey squirrels in North America, the species primarily affected, according to the Michigan Department of Natural Resources.

Do Zombie Squirrels Pose A Threat To Humans?

If you are a squirrel, rabbit, or woodchuck, you may need to be cautious about leporipoxvirus infection. While documented cases of transmission in nature have been limited to squirrels, laboratory settings have shown transmission to rabbits and woodchucks. If you are uncertain about your species identity, a quick look in the mirror, consultation with a medical professional, reflection on your ear length, or reaction to woodchuck-related inquiries may provide clarity.

For humans, the risk of infection appears to be minimal, even if one were to consume an infected squirrel. While the potential for the virus to mutate and infect humans cannot be ruled out entirely, current evidence suggests that encountering a “zombie squirrel” does not warrant the same level of concern as facing a human zombie.