As humans face a coronavirus pandemic, rabbits are at risk of being wiped out by their own disease, the Rabbit Hemorrhagic Disease Virus, or RHDV. An excerpt from Susan Payne’s book, Viruses described it as a highly infectious virus that affects domestic, wild and feral rabbits alike and has a very high mortality rate.
RHDV is a calicivirus, meaning that it only affects rabbits, hares and pikas. The more recent strain of the disease, officially called Rabbit Hemorrhagic Disease Virus Type 2 (RHDV-2) can cause internal bleeding and swelling, and it typically isn’t discovered until after the animal’s death.
The disease is characterized by acute necrotizing hepatitis (liver failure) and disseminated intravascular coagulation. Disease progression can be rapid, sometimes resulting in sudden death in the absence of clinical symptoms.
Matt Gompper, a disease ecologist and head of the Department of Fish, Wildlife and Conservation Ecology at New Mexico State University, told Fox-8 News that a loss of the rabbits could negatively impact the ecosystem, causing plant overgrowth and a loss of food for the animals that prey on them. An article from The Center for Food Security Public Health noted that the loss of these rabbits has had particularly negative effects in Europe, leaving the endangered Iberian lynx reduced food source.
Here’s what you need to know:
Rabbits Have Had Multiple Epidemics of RHDV In the Past
Following an outbreak that devastated the rabbit population, researchers conducted a study on RHDV in 1998, and they tracked the disease from Australia‘s mainland in October of 1995 to wild European rabbits. According to the study, it only took one month for the disease to severely reduce the rabbit population:
During November 1995, RHD reduced the rabbit numbers on the site by 95%. Approximately 3% of the population survived challenge by RHD and developed antibodies. Most of the antibody-positive survivors were 3- to 7-wk-old when challenged. Many rabbits died underground, but counts of rabbit carcasses found on the surface indicated that approximately 1 million rabbits had died above ground in the National Park, and that > 30 million rabbits may have died in adjacent areas during the November epidemic.
The virus popped up again in the 1980s, where it had a mortality rate between 55%-75%. The new variant of RHDV-2 also appeared in France in 2011. According to Fox-8 News, the latest strain of this disease popped in New Mexican rabbits in March 2020 and traveled through Texas, Arizona, Colorado and California.
The latest strain of the virus is “threatening to wipe out entire populations across multiple states,”Fox-8 reported.
How Does RHDV Spread?
Gompper told Fox-8 News that there are some parallels between RHDV-2 and COVID-19: it likely spilled over from domestic to wild rabbits and appeared so suddenly that health officials didn’t realize it. Moreover, it is easily transferable between rabbits, according to Payne’s Viruses.
However, researchers have made some important discoveries. For example, according to the Center’s article, insects can carry the virus over long distances, and flies can carry it up to nine days and transmit it through bites. The article also noted that flies’ feces and vomit can also retain the virus and can infect rabbits if it is present on vegetation.
The virus has yet to infect a human, however. According to an article from Veterinary Information Network, “RHDV2 is not zoonotic and has no known impact on human health.”
Unfortunately, for rabbits, the virus is deadly: “mortality rates range between 40% and 100% for RHDV/RHDVa and 5% and 70% for RHDV2,” according to the Veterinary Information Network article. The USDA has asked people who see multiple dead wild rabbits to contact their state wildlife officials.
How Can You Protect Your Pet Rabbits?
For people who have pet rabbits, the United States Department of Agriculture (USDA) says to check if they are feverish, hesitant to eat or show trouble breathing; they also advise owners to maintain good hygiene with handwashing and clean environments, keeping them out of the wild and maintaining clean food sources.
According to The Center for Food Security Public Health, RHDV can spread via contaminated food, bedding and water. Payne’s Viruses noted that the nasal and oral cavities, as well as potential interactions with flies carrying the virus, are the most likely ways a rabbit could be infected.
The Center also said the best disinfectants to kill RHDV include solutions with 10% sodium hydroxide, 1-2% formalin, 2% One-stroke Environ, 0.5% sodium hypochlorite and 10% household bleach. There are also vaccines; the Veterinary Information Network reported that Filavac is a vaccine effective against both RHDV strains while Nobivac Myxo-RHD only defends against RHDV and Eravac only treats RHDV-2.