Rabbit Hemorrhagic Disease
RHD, also known as viral hemorrhagic disease, is a highly contagious and fatal disease of Lagomorphs that can be caused by two related Caliciviruses.
- Rabbit Hemorrhagic Disease Virus Serotype 1 (RHDV1 or RHDVa) only affects rabbits in the genus Oryctolagus, which includes most domestic rabbits and wild European rabbits.
- Rabbit Hemorrhagic Disease Virus Serotype 2 (RHDV2) affects Oryctolagus rabbits and several other species of rabbits, including wild jackrabbits and hares (Lepus), wild American cottontails (Sylvilagus); other rabbits and pikas (family Ochonotidae) may be susceptible.
RHD is endemic in most parts of Europe, Australia, New Zealand, Cuba, and parts of Asia and Africa.
Considered a foreign animal disease, cases caused by RHDV1 occurred in the United States in 2000, 2001, 2005, and 2010, and Canada in 2011.
A newer strain, RHV2 emerged in France in 2010 and has since spread across Europe and Australia.
It arrived in southwestern Canada in 2018, leading to cases in domestic rabbits in Ohio, Washington, and New York City.
In March 2020 a widespread outbreak of a genetically different strain of RHDV2 emerged in wild and domestic rabbits in the southwestern U.S. and northern Mexico.
Since May 2020 it has been spreading in southern California and many other U.S. states, killing both wild and domestic rabbits.
The incubation period for RHD usually ranges from 1 to 5 days but can be up to 9 days.
It causes liver inflammation (hepatitis) and prevents the blood from clotting. Rabbits often die suddenly without showing any outward signs of illness, but may also have:
- Lethargy
- Inappetence
- Fever
- Jaundice
- Spasms or seizures
- Breathing difficulties
- Vocalizations
- Bleeding from nose, mouth or body orifices
Death is due to internal hemorrhaging and liver impairment.
In the current outbreak, reported average mortality has been about 60% (range 20 to 100%).
Rabbits of all ages are affected by RHDV2, while rabbits younger than 8 weeks are usually spared from RHDV1.
Can people or other animals get RHD?
No; RHD viruses are only known to affect lagomorphs of the family Leporidae (rabbits and hares).
Other types of Caliciviruses have been found in people, cattle, sea lions, and cats.
Controlling the Spread of RHD
Rabbits may inhale or ingest this virus.
It can persist in the environment for 4 months and is transmitted through direct contact with infected domestic or wild rabbits or indirect contact with objects (cages, feeders, grooming equipment, toys), or people and clothing contaminated by rabbit secretions or excretions.
Transmission occurs after consumption of contaminated food (such as hay) and water, or exposure to rabbit products (meat, fur, fiber, skins, offal, droppings, Urine).
Insects, rodents, birds, or domestic animals may become contaminated with virus and transfer it to rabbits.
Dogs, coyotes, birds of prey, and other predators can spread the virus by moving infected rabbit carcasses.