Rabies moving north through Wyoming, but risk to humans remains low

Posted 11/24/20

Though extremely rare, rabies affects a diverse number of animal species in Wyoming. One particularly pungent rodent is carrying the disease north, slowly waddling through the state and concerning …

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Rabies moving north through Wyoming, but risk to humans remains low


Though extremely rare, rabies affects a diverse number of animal species in Wyoming. One particularly pungent rodent is carrying the disease north, slowly waddling through the state and concerning some officials. And its progress, although slow, is being diligently tracked.

Skunks, along with bats, represent the vast majority of wildlife species carrying rabies in the state, said Dr. Myrna Miller, associate professor and veterinary virologist at the University of Wyoming and supervisor of virology at the Wyoming State Veterinary Laboratory. And, due to skunks, it appears the disease is becoming more prevalent.

In 2018, 20 rabid skunks were discovered by the state vet lab in Laramie County. They also found a single horse and a single cow infected through contact. The following year, reports of six infected skunks, an infected raccoon and a single bat moved to Goshen County. Miller expects the northward trend of the parasitic disease to continue, but said there is no need to panic. The parasitic disease’s movement “is more of a scientific curiosity than it is direct public health impact,” she said in an interview Friday.

More concerning to Miller and state wildlife officials is how the information provided to the general public may be interpreted. Simply reporting the news can spark fear and potentially hurt populations of the two important species — especially with folks hyper alert about current community health issues.

However, although skunks can be a nuisance due to their odor and ability to spray, and bats can be creepy and possibly get in your home, “they are often shy, nocturnal animals,” Wyoming Game and Fish Nongame Program Supervisor Zack Walker said.

He said both skunks and bats play important roles in our ecosystem.

“Like all species, [skunks] perform a role in their environment,” Walker said. “Skunks are typically nocturnal and are omnivores. They will eat insects and often feed on agricultural pests such as grasshoppers, grubs, and beetles. They can also eat mice, moles, and other small mammals.”

He added that, “it is important to remember that not all skunks will get rabies.”

As for bats, scientists have discovered that small ones can catch up to 1,000 or more small insects, like mosquitoes, in a single hour. A nursing mother bat eats the most — sometimes catching more than 4,000 insects in a night.


‘Crazy behavior’

Generally speaking, the parasite that causes rabies is fairly easy to recognize. The parasite makes infected species very aggressive, said Miller.

“Rabid skunks will climb into a kennel with three rottweilers and take them on. You know, crazy behavior,” she said. “But that’s how the parasite or rabies maintains transmission.”

That statement is where most of the interest in parasitic diseases excites scientists and scares the public.

As noted American neuroendocrinology researcher, author and professor of neurology Robert Sapolsky once put it, “there are creatures out there that can control brains.”

Rabies is one of those parasites that controls the brain of its host. Although the actions of the virus have been recognized for centuries, there has yet to be research in why it picked the brain to propagate.

“There are lots of ways rabies could have evolved to move between hosts. The virus didn’t have to go anywhere near the brain. It could have devised a trick similar to the one employed by the agents that cause nose colds — namely, to irritate nasal-passage nerve endings, causing the host to sneeze and spritz viral replicates all over, say, on the person sitting in front of him or her at the movies,” Sapolsky wrote in Scientific American in 2003. “Instead, as we all know, rabies can cause its host to become aggressive so the virus can jump into another host via saliva that gets into the wounds.”

There are myriad parasites, many newly discovered as we learn more about them. Rabies is a fairly well-known parasitic disease; it’s been around and known by scientists for thousands of years. But beyond rare cases of public safety, its importance is more of a case study of how scientists may research parasites in the future.

While the state vet lab’s surveillance of rabies, funded by the Wyoming Animal Damage Management Board (ADMB), seems to be a study of extremely rare cases, the knowledge gained as the parasite moves into new neighborhoods is a critical exercise of science.


Taking precautions

Ten people in the state have paid for rabies vaccinations in 2020, but only one person has ever been reported to have died from rabies in state history: A 77-year-old Lander woman who contracted the viral disease in 2015 after being bitten by a bat.

In the case of skunks and bats, you should simply avoid them, Walker said.

“If a landowner finds a skunk on their property, the best thing to do is to leave it alone,” he said.

The same goes for bats, according to Nicole Bjornlie, state nongame mammal biologist and leading expert on bat populations for the Game and Fish. That said, if you suspect “wet contact” with either species, you should immediately call the department.

It is extremely important the suspected animal be found and their brains be available for testing, wildlife managers say; vaccinations can be avoided if the animal is collected properly.

Left unchecked, the disease is always fatal to its host, but it can be effectively treated with a series of rabies shots, which cost about $3,000.

The most important action you can take to avoid rabies is “to make sure that outside pets are vaccinated for rabies to help reduce any issues,” Walker said.

But it’s not just pets that can get the disease. According to the state veterinary lab, dogs and cats are numbers three and four on the list of infected animals, but cows, mules and horses, rabbits, other rodents and even bighorn sheep, alpaca, and black bears have been tested for the disease this year. There have been 29 animal species tested at the lab.

A total of 610 animals have been tested for rabies so far this year, with the top five being skunks, bats, dogs, cats and raccoons, along with 19 cows. Of those animals suspected of having rabies, 256 were tested after having contact with humans and only 10 came back positive for rabies. Only after the positive tests were the people in contact required to get vaccinated.

More than anything, Walker said, it is important to know what to do if someone has a worry about a rabies infection. First, it’s important that someone is contacted to make sure a sick skunk or bat is handled humanely by someone who is familiar and comfortable with what to do. A local game warden is a good place to start — they can send samples to the appropriate veterinary laboratories.

The animal carcass is useless if the brain has been compromised, Miller said. She has received headless skunks, which can’t be tested because the brain is where the parasite lives; bats are even more delicate.

“If you kill this critter with a size 12 [boot], there’s not going to be anything left for us to test because that brain is going to be shattered,” Miller said during last week’s ADMB meeting.

She added that, “Basically, anytime there is a neurological animal with human exposure, it is highly, highly recommended you send that sample in and get it tested.”