Rabbit Hemorrhagic Disease

Rabbit hemorrhagic disease is a serious and extremely contagious viral disease of domesticated and wild rabbits. Morbidity and mortality rates are high in unvaccinated animals; on some farms, most or all of the rabbits may die. This disease has also caused dramatic declines in some wild rabbit populations, particularly when it is first introduced. This has had a detrimental effect on some ecosystems in Europe, where wild rabbits are an important food source for certain endangered predators, such as Iberian lynx (Lynx pardinus). Conversely, rabbit hemorrhagic disease has been used to help control excessive numbers of wild, non-native European rabbits (Oryctolagus cuniculus) in Australia. The origins of rabbit hemorrhagic disease are not completely understood. The causative virus, rabbit hemorrhagic disease virus (RHDV), may have emerged from avirulent caliciviruses that circulate asymptomatically in European rabbits. The first known outbreak occurred in China in 1984, apparently spread by Angora rabbits that had been imported from Europe. Within 9 months, this disease had killed 14 million domesticated rabbits in China. By the late 1990s, outbreaks had been reported from forty countries, and rabbit hemorrhagic disease had become endemic in a number of areas throughout the world. Other regions, including the Americas, have experienced periodic outbreaks in domesticated rabbits. However, the species of wild rabbits found in North America are not susceptible to these RHD viruses, which facilitates eradication. A new variant called RHDV2 emerged in Europe in 2010, and has spread widely among domesticated and wild rabbits there. This virus has also been found in Australia. RHDV2 affects animals vaccinated against older RHD viruses, as well as unvaccinated rabbits. It can also cause illness in some species of hares. Whether RHDV2 could affect any wild North American lagomorphs is not yet known.