Rabbit Hemorrhagic Disease Virus Type 2, or RHDV2, could decimate Long Island's wild rabbit population, scientists fear

Pet bunnies love spring grass but keep those family members inside, experts say — or risk dooming Long Island’s wild rabbits by spreading a deadly hemorrhagic disease.

The virus, known as Rabbit Hemorrhagic Disease Virus Type 2, or RHDV2, can cause rabbits to struggle with breathing, act nervously or lethargically, or bleed through the nose.

So far, scientists do not believe there have been any cases in wild rabbits east of the Mississippi River, said Jenny Dickson, wildlife division director at the Connecticut Department of Energy and Environmental Protection.

But the virus killed pet rabbits at a New York City boarding facility in 2020 and last year there was a case in Montgomery County, about 50 miles northwest of Albany, officials said.

And the rapidity with which the virus can spread raises alarms. In Australia, two predecessor viruses — RHDV1 and RHDV1a — were used to control wild rabbits, but the sixth-biggest nation was overtaken in less than 18 months when the newer RHDV2 somehow arrived.

“It’s just so prevalent in certain areas,” said Jean Mellano, 69, of Greenport, a volunteer with the nonprofit Long Island Rabbit Rescue who tracks cases of the virus. “I’m very worried...because it is such a highly contagious virus.”

‘Very hardy’

RHDV2 springs from the original Rabbit Hemorrhagic Disease Virus that first hit Europe's rabbits in 1984. 

In 2010, RHDV2 was identified. It reached the United States eight years later, and since 2020, New York, New Jersey and Connecticut have had a handful of outbreaks in pets.

Texas, Colorado and Arizona have had some of the latest cases, according to the Wildlife Health Information Sharing Partnership website, overseen by the U.S. Geological Survey.

The virus, though “very hardy” and easy to spread, “is no risk to humans or other animals,” Krysten Schuler, an assistant professor in the Department of Public and Ecosystem Health at Cornell University, said by email.

But scientists fear the virus could decimate wild rabbits, including the plentiful eastern cottontail and the already imperiled New England cottontail, a Long Island native with a tell-tale black spot on its forehead and black lines on its ears.

New England cottontails were seen from Babylon to Montauk and on the North Fork as recently as the 1970s, according to Paul F. Connor’s “The Mammals of Long Island,” but the state Department of Environmental Conservation says they are now only found in Dutchess, Putnam, Columbia and Westchester counties.

New England cottontails are listed by the state DEC as of “special concern.”

“The species likely will become extirpated in the state” or vanish, according to the Cornell University Cooperative Extension, citing development, cars, ticks, predators and rivalry with eastern cottontails imported by hunters in the early 1900s.

How to protect rabbits

There is no treatment for what Mary Ann Maier, co-founder of Long Island Rabbit Rescue, called “bunny Ebola,” but there is a vaccine that won emergency approval in 2021 from the U.S. Department of Agriculture.

Administering the shots are a “herculean task,” said Maier, who explained the annual vaccines require a booster 21 days after the first shot — and the vials, which must be used within 24 hours after opening, contain 20 doses.

Setting up the double appointments and securing prepayments — to ensure all owners show up — is complicated for often-overworked veterinarians, she said.

Safeguarding bunnies — increasingly popular pets that can use litter boxes just like cats though they are much more fragile — is crucial because RHDV2 can latch onto just about anything and everything, from tires to hay, especially if imported from an outbreak area.

The virus is shed in secretions from infected rabbits and is spread by direct contact, insects or contaminated surfaces such as shoes and is very stable in the environment, according to the Schwarzman Animal Medical Center in New York City,

Dr. Katherine Quesenberry, the nonprofit’s chief medical officer, said by email: “The RHDV2 virus can survive on surfaces for over 100 days.”

She added the virus can withstand extreme temperatures and advised cleansing with a 10% bleach solution.

In addition to ensuring pet rabbits have zero contact with wild peers, New Jersey state veterinarian Dr. Amar Patil recommended 30-day quarantines for any newly-adopted bunnies, washing hands before and after touching or working with them, and asking visitors to wear “gloves, shoe covers, hair covers and coveralls.”

Rabbits already kept outside can remain so.

“Currently, infection with RHDV2 virus is rare in New York, so moving animals indoors is not necessary,” Hanna Birkhead, a state Department of Agriculture and Markets spokeswoman, said by email.

But, said experts, indoor pets should stay inside.

Long Island Rabbit Rescue, for instance, requires its adopters to promise no outside walks, as Maier says nonnative bunnies have no defenses to local diseases and pests, from maggots to parasites.

“We keep livestock outside...a companion animal should not be at a distance to its family,” said Maier.

Added Dickson: “We really don’t want people to let their rabbit free range or turn their rabbit loose if you decide you don’t want your rabbit anymore. These are the kinds of things we would really hope people would avoid doing just because they would really [devastate] our native rabbits.”