A Mysterious Virus Is Killing Texas Rabbits

May 8, 2020

From Texas Standard:

 

A couple of months ago, 30 dead rabbits were found near Fort Bliss.

 

That's when Ken Waldrup, who works for the Texas Department of State Health Services, as a regional zoonosis control veterinarian in El Paso, where Fort Bliss is located, got a call.


After performing necropsies on six of the rabbits, he sent their tissue samples to the Texas Veterinary Medical Diagnostic Lab in College Station.

 

Waldrup was looking for two diseases in particular: tularemia, also known as rabbit fever, and bubonic plague – both of which pop up in West Texas rabbits from time to time, and can spread to humans.

 

But it wasn’t either of those. Then, a clue came to Waldrup from a neighboring state.

“It was about this time that I found out that the New Mexico Fish and Game had also experienced a rabbit die-off. They were the first ones to actually find the RHD,” he said.

RHD stands for rabbit hemorrhagic disease. It doesn’t affect humans, but among rabbits it’s deadly, and highly contagious.

After Waldrup learned what had caused the deaths at Fort Bliss, he started seeing dead jackrabbits and cottontails around El Paso. And he wasn’t the only one.

“The main thing that we see in El Paso is large numbers of dead, wild jackrabbits. You might be out walking and then you come across a cluster of three or four dead rabbits on your hike,” said Marc Silpa, a veterinarian in El Paso.

Silpa is getting a lot of questions about the virus, but he’s not treating a lot of sick rabbits.

“The first sign that most people notice is the dead rabbit. It’s a fairly fast disease,” he said. “If it’s one of the ones that’s going to die, likelihood is you’re not going to be able to save it.”

This is the first time Waldrup and Silpa have encountered the disease. There have only been a few isolated cases among animals in captivity in the United States; the other big outbreaks have been in Europe, Australia and Asia. The virus can decimate domestic rabbit herds. And in the wild, it has the potential to harm not just rabbits, but animals further up the food chain that rely on them, like coyotes.

“We’ve got a new crop of coyotes being born literally right now, and there won’t be as many rabbits around. And so we’ll have these young, inquisitive coyotes looking for other food sources, an that’s probably going to lead them into trouble,” Waldrup said.

The virus hasn’t wiped out all the rabbits in West Texas. Some rabbits get it and survive, others don’t. But it’s not clear what separates those two groups, and that’s just one of the virus’ many unknowns.

“We’re not sure where this thing came from. You know, how did it get here? Where did it come from? This one’s kind of unprecedented,” Waldrup said.

Veterinarians and epidemiologists are in largely uncharted territory. What is clear, however, is that the dead rabbits in El Paso are part of a much larger outbreak – the biggest one ever documented in North America. And the virus is still spreading.

“When we got previous outbreaks, yes the domestic rabbits would be affected, but this was a game changer when it got into the wildlife,” Silpa said.

It’s difficult to measure the exact scope of the spread, but there are now confirmed cases throughout West Texas, as well as in the Panhandle. Earlier this week, the Texas Animal Health Commission confirmed cases in domestic rabbits in two central Texas counties: Lampasas and Hamilton.

And that’s just in Texas. In just a couple months, RHD has also been found in northern Mexico, New Mexico, Arizona, Nevada and Colorado.

The spread has caught the attention of rabbit breeders like Angela Arthur, who raises rabbits in the Panhandle near Crosby County, mostly for kids in clubs and the National FFA Organziation who show them.

“The general public is not aware of it,” Arthur said. “A lot of people think it’d be fun to let their rabbit loose in their backyard, and just have fun eating weeds and living a full life in the backyard. And that’s the worst scenario to catch this disease.”

According to the Texas Animal Health Commission, the best way to protect domestic rabbits is to keep them inside, clean and disinfect cages as often as possible and make sure rabbits don’t eat local forage.

There is a vaccine for the virus, but it’s not approved for use in the United States. Veterinarians in Texas are currently working to order some from European manufacturers. But getting through the red tape of importing an unapproved drug will take time, and it will be more expensive than a typical treatment

 

Note: This story uses the word ‘rabbit’ to refer to jackrabbits, which are related to rabbits, but are actually hares. rabbit hemorrhagic Disease affects both rabbit and hare species.

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