Deadly Hemorrhagic Disease Confirmed in Wild Rabbits

A potentially devastating situation has been confirmed in multiple states with the discovery of viral Rabbit hemorrhagic disease, and a variant of the virus that causes it. The ramifications on wild populations of rabbits, along with predators that feed on them, could be huge.

Deadly Hemorrhagic Disease Confirmed in Wild Rabbits

A cottontail rabbit hides in the sagebrush in Utah, one of several states with confirmed cases of Rabbit hemorrhagic  disease. (Photo: Utah DNR)

About 15 years ago on a pronghorn hunt in southeast Wyoming, our crew tagged out on the first day of the week-long hunt. To say it was a fine day of hunting, shooting and toasts at dinner was an understatement.

After sleeping in the next morning, taking our animals to the processor and placing orders at taxidermy shop, we didn't know what to do. One person made plans to return home and flew out the following morning. The rest of us enjoyed sleeping in, hot coffee and relaxing.

Fortunately, one of our gang had a .22 rifle and a few bricks of ammo. A second rifle from our hosts and more ammo turned afternoons into rabbit plinking sessions. My buddy and I shot rabbits around the camphouse until we couldn't find any more rabbits. The next day almost all the dead rabbits were gone. Scavengers took them in the night. Coyotes, we figured, but who knows what else was enjoying the easy bounty.

I thought of that trip recently while flying to Wyoming and reading Susan Orlean's outstanding story in The New Yorker about Rabbit hemorrhagic disease. As with viruses, RHD it has a mutated variant known as Rabbit hemorrhagic disease serotype 2 (RHDV-2). The devastating disease is fatal to domestic and wild rabbits. It has been confirmed in at least six western states since May.

But Orlean's story began in February in a Manhattan specialist's clinic with dying rabbits and the shocking discovery of RHDV-2. Given the cramped confines of New York City and potential impact of such a contagious, fatal disease on wild and domestic rabbit populations there and in the eastern half of the United States, officials were scrambling. 

From her story, "The Rabbit Outbreak":

Regardless of the symptoms, though, the mortality rate for RHD can reach a gloomy hundred per cent. There is no treatment for it. The virus’s ability to survive and spread is uncanny. It can persist on dry cloth with no host for more than a hundred days; it can withstand freezing and thawing; it can thrive in a dead rabbit for months, and on rabbit pelts, and in the wool made from Angora-rabbit fur, and in the rare rabbit that gets infected but survives. It can travel on birds’ claws and flies’ feet and coyotes’ fur. Its spread has been so merciless and so devastating that some pet owners have begun referring to it as “rabbit Ebola.”

Rabbit populations are cyclical. All or a great percentage of them dying would be horrible.

Predators Impacted

If you're thinking that RHD is just a disease and that animals get diseases so no big deal, you're partially correct. Animals do get viruses and diseases, they die — sometimes in large numbers — and that's how things are. It happens with humans sometimes, too.

Rabbits can't handle RHD well, though. After its discovery in 1984 in China, the virus blew through Asia, Europe, the United Kingdom, Australia and the Middle East. It killed an estimated 140 million rabbits just in China after the initial outbreak. In England, officials warned citizens not to bury pets because the virus could linger in the soil. It was contained in the United States, but has been a concern for the last couple of decades as animal trade — illegal and legal — has grown.

The big deal about a brazillion rabbits dying, though, is what eats them. Rabbits are a significant food source for many species, including humans. In the animal world they're like the Burger King Whopper or In-n-Out Double Double, convenient just about anywhere or anytime. Coyotes, of course, work on rabbits. Bobcats and lynx. Badgers, probably, and wolverines. Bears. Wolves probably enjoy rabbits as a snack. Even feral hogs, which are opportunistic, likely wouldn't pass up a bunny buffet, nor will snakes.

This doesn't include the myriad avian species that scavenge, from raptors to vultures. Owls, magpies, crows ... even smaller birds arrive to pick at insects attracted to the carcass if something larger hasn't gotten to it.

Whether it's in a Florida swamp, Mississippi pasture, New York thicket or California grassland, and whether it's a hawk diving swiftly or a hunter with a 20-gauge, rabbits are food sources. To lose them from the life cycle, to have that massive hole or gap in the dynamic, would be bad.

What's Next?

Utah officials say Rabbit hemorrhagic disease was confirmed in domestic rabbits in Sanpete County in June, has now been confirmed there in wild rabbit populations.

Previous confirmations include California, Nevada, Colorado, Texas, New Mexico and Arizona. It's not just a "west" or "desert" thing, though. Remember the domestic rabbits in New York City? The virus spreads quickly, as Orlean explained in the New Yorker story: in the body, on the fur, after death, after burial. Officials in England years ago warned residents to not bury pet rabbits in the garden or yard, as the virus could remain in the soil. It also can be spread by scavengers and predators.

California officials confirmed RHDV-2 for the first time after a black-tailed jackrabbit carcass was found in May near Palm Springs. It was one of about 10 rabbit carcasses found on the property. California officials say infected rabbits and jackrabbits "may exhibit no symptoms leading up to their sudden death, or may suffer from fever, swelling, internal bleeding and liver necrosis." They added that all rabbit, jackrabbit, hare and pika species are likely susceptible.

Rabbits may become sick one to five days after exposure and have symptoms of fever, lethargy, a lack of appetite, difficulty breathing and frothy blood coming from their nose just prior to death. The virus causes liver inflammation that prevents blood from clotting and eventually the rabbit dies from internal hemorrhage (bleeding). There is no treatment for RHDV-2.

While people, dogs and other animals are not susceptible to RHDV-2, they can carry the virus from one location to another on their feet or other contaminated items. The virus can survive for months in the environment, and rabbits can be infected by direct contact to sick rabbits or through contact with the urine or feces of sick rabbits.

If you're out and about and see dead rabbits, or are hunting this fall, be aware. Don't shrug it off as just another weird thing. Rabbits may be low on our list of considerations or wild game pursuits, but they're important in the list of food sources for wildlife.

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