Rabbit Hemorrhagic Disease (RHD) is a severe, highly contagious viral infection that primarily affects domestic and wild rabbits. Rabbit Hemorrhagic Disease Virus Type 2 (RHDV2), which emerged in France in 2010, is the strain of concern. This virus causes acute liver damage and internal bleeding, often resulting in high fatality rates in susceptible populations. Given the rapid spread of RHDV2 across continents, public concern regarding potential human exposure is a common question.
Understanding the Virus in Rabbits
Rabbit Hemorrhagic Disease is caused by a virus belonging to the Lagovirus genus within the Caliciviridae family. The disease is characterized by a rapid progression and sudden onset of symptoms in lagomorphs. The incubation period for RHDV2 is typically between three and five days, though it can be shorter. The virus attacks the liver, causing acute necrotic hepatitis and disseminated intravascular coagulation, which disrupts the body’s clotting ability. Infected animals may display non-specific signs such as fever and lethargy, or they may die suddenly without any prior symptoms. In some cases, rabbits may be found with a bloody discharge from the nose or mouth, which is a result of the internal hemorrhaging.
Mortality rates from RHDV2 are highly variable, ranging from 5% to as high as 70% in affected rabbit populations. This high contagiousness and lethality pose a serious threat to both commercial rabbitries and wild lagomorph species. The devastation caused by the disease impacts ecosystem dynamics where wild rabbits are a major food source.
Direct Risk to Human Health
Despite the severity of Rabbit Hemorrhagic Disease in lagomorphs, the virus is not considered a threat to human health. RHDV2 is not a zoonotic disease. There have been no documented cases of human infection globally since the virus was first identified in the 1980s.
The biological reason for this lack of human infection lies in the virus’s strict host specificity. RHDV2 is a Lagovirus, a type of calicivirus that has evolved to target specific cell receptors found almost exclusively in the tissues of lagomorphs. The necessary biological components for the virus to attach to and replicate within human cells are absent. Non-lagomorph species, such as domestic pets and livestock, are naturally resistant to the disease. Studies involving the inoculation of RHDV into various other vertebrate species have consistently failed to produce the disease or viral replication. While humans can mechanically carry the virus on clothing or shoes, the virus cannot infect or make a person ill.
How the Disease Spreads Among Animals
The virus is extremely resilient and spreads efficiently between rabbits. Direct contact between a healthy rabbit and an infected one is a primary route, as the virus is shed in all bodily excretions, including urine, feces, and respiratory secretions. The oral route is considered the most common way for a rabbit to become infected.
RHDV2 is also easily spread through contaminated non-living objects, known as fomites. Items such as cages, food and water dishes, bedding, clothing, and footwear can harbor the virus and transfer it to new hosts. Personnel who handle infected animals can unintentionally become mechanical vectors, carrying the virus on their hands or clothes. Mechanical transmission is also accomplished by various insects, such as flies, which can carry the virus over short distances. Additionally, scavengers or predators that consume an infected rabbit carcass can excrete the virus in their feces, contributing to environmental contamination. The hardy nature of the calicivirus allows it to persist in the environment for months, especially in organic materials or infected carcasses, making control difficult.
Essential Precautions for Pet Owners
Rabbit owners should focus on strict biosecurity measures to protect their pets from RHDV2, especially considering the virus’s environmental stability. Meticulous hygiene includes washing hands thoroughly with soap and water before and after handling rabbits or their equipment. It is also recommended to change clothes and clean the soles of shoes before entering a rabbit area, particularly if the owner has been in an area frequented by wild rabbits.
Any new rabbit must undergo a strict quarantine period, isolated from existing pets for a minimum of 30 days to observe for any signs of illness. Cages and equipment should be regularly disinfected with an effective solution, such as a 10% bleach-to-water mixture. Owners should take steps to minimize contact with wild rabbits by keeping domestic animals indoors or in elevated, secure hutches. Vaccination remains the most effective tool in preventing the disease in domestic rabbits, and owners should consult their veterinarian about the appropriate RHDV2 vaccine schedule. If a rabbit shows sudden signs of illness, such as lethargy or appetite loss, or if a sudden death occurs, it is important to contact a veterinarian immediately. Timely testing and containment of a potential outbreak require prompt veterinary attention.