A deadly and highly contagious rabbit virus, first identified in the U.S. last summer, has begun infecting Southern California’s wild rabbits, with deaths confirmed in Orange, San Bernardino, Riverside and San Diego counties since early May. At least one domestic rabbit, in San Bernardino County, also has been killed by the disease.
The disease, known as Rabbit Hemorrhagic Disease Virus Type 2 or RHDV2, is unrelated to the coronavirus and doesn’t infect humans.
But for rabbits it could be more devastating — particularly for those in the wild. It’s believed to kill 90% of the rabbits it infects, it can live without a host on surfaces for several months, and it can be introduced into uncontaminated areas by birds and other animals.
“Because this virus is already established in wild animals and is already in multiple states, it’s probably a virus we’re going to have to live with for some time,” State Veterinarian Annette Jones says in a video discussing the disease. “We need to think of ways to protect our animals rather than totally eradicating the virus.”
While there is a vaccine, it’s not widely available in the U.S. and it must be injected. That could make it virtually impossible to control the disease in the wild.
The disease has claimed the lives of at least six wild rabbits in Orange, Riverside, San Bernardino and San Diego counties, according to Kirsten Macintyre, spokesperson for the California Department of Fish and Wildlife.
However, limited testing resources mean that additional wild animals are usually not tested in counties once one infection has been identified, Macintyre said. There are exceptions if the wild animals are in an area with domestic rabbits, are a threatened or endangered species, or have other unusual circumstances that merit additional testing, she said.
“Accordingly, there are undoubtedly many more affected rabbits in those counties that are not tested,” she said.
A single domestic rabbit in the state is confirmed to have succumbed to the disease, according Steve Lyle of the California Department of Food and Agriculture. That agency is monitoring the infection of domestic pets.
That death occurred in a small, backyard rabbitry in San Bernardino County on July 10, according to the department’s website.
“The rabbit died suddenly without showing clinical signs prior to death,” the site says. “The detection was in an area where wild rabbits had previously been detected positive for RHDV2. The rabbitry is currently under state quarantine and movement of rabbits on and off the property is restricted.”
‘Huge toll’ ahead
The original version of the Rabbit Hemorrhagic Disease was first identified in China in 1984 and eventually spread throughout most of the world, with U.S. cases confirmed from 2000 to 2010, according to the state Department of Food and Agriculture. It was never identified in California, reaching only as far west as Utah.
It only affected a few types of rabbits, a genus known as Oryctolagus, which includes most domestic rabbits and wild European rabbits, according to the department. That helped minimize its spread.
The new strain, however, also infects wild jackrabbits, hares, cottontails, and pikas — all of which were unaffected by the original virus. It was first identified in France in 2010, with the first U.S. case confirmed in Seattle in July 2019, followed by cases in Ohio and New York City. Early cases were all domestic rabbits, so could be isolated and contained with sufficient vigilance.
But earlier this year, cases began being identified in the wild throughout the Southwest, with the first California case identified near Palm Springs in early May.
“Before this, it had not been in the wild at all,” said Michelle Hawkins, a professor of exotic animal medicine at UC Davis. “This is entirely different. This is what we absolutely wanted to avoid. It’s going to take a huge toll on the population of wild rabbits.”
She wouldn’t rule out the virus virtually eliminating wild rabbits in California and beyond, but pointed to other possible scenarios. They include the virus mutating to something less deadly or, a less likely possibility, the animals developing herd immunity.
The virus is not believed to infect animals other than rabbits. It could reduce food supplies for wildlife with diets heavily reliant on rabbits — including bobcats and birds of prey — although Hawkins said those animals have other food sources in their diets.
Among animals that can become infected, the riparian brush rabbit and pygmy rabbit are both endangered and are of particular concern. So far, the wild animals known to have been killed by the virus in California have been limited to black-tailed jackrabbits and desert cottontails.
Precautions for owners
Symptoms can included fever, lack of appetite, breathing difficult and bleeding from body cavities. But rabbits are known for hiding symptoms of illness and, like the domestic rabbit in San Bernardino County, can drop dead without displaying any previous indication of infection.
Among precautions for rabbit owners recommended by the Department of Food an Agriculture:
- Keep rabbits in hutches or cages that are elevated off the ground.
- Don’t let rabbits graze or roam in a yard if wild rabbits are in the area.
- Avoid contact with other people’s rabbits.
- Prevent dogs, coyotes, insects, birds, rodents and other animals from entering your pets’ area. Those animal can carry the virus on their feet, fur or feathers.
There are vaccines abroad but because they have not yet been approved in the U.S., there is limited availability. Contact your veterinarian for more information.
Those who see dead wild rabbits are asked to report their sightings at to the Department of Fish and Wildlife at 916-358-2790 or at the department’s mortality report site online at wildlife.ca.gov.
Source: Orange County Register