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Rabbit hemorrhagic disease (RHD), also known as viral hemorrhagic disease (VHD), is a highly infectious and lethal form of
viral hepatitis Viral hepatitis is liver inflammation due to a viral infection. It may present in acute form as a recent infection with relatively rapid onset, or in chronic form. The most common causes of viral hepatitis are the five unrelated hepatotropic v ...
that affects
European rabbit The European rabbit (''Oryctolagus cuniculus'') or coney is a species of rabbit native to the Iberian Peninsula (including Spain, Portugal, and southwestern France), western France, and the northern Atlas Mountains in northwest Africa. It has ...
s. Some viral strains also affect hares and cottontail rabbits. Mortality rates generally range from 70 to 100 percent. The disease is caused by strains of ''rabbit hemorrhagic disease virus'' (RHDV), a
lagovirus ''Lagovirus'' is a genus of viruses, in the family ''Caliciviridae''. Lagomorphs serve as natural hosts. There are two species in this genus. Diseases associated with this genus include: necrotizing hepatitis leading to fatal hemorrhages. Taxon ...
in the family ''
Caliciviridae The ''Caliciviridae'' are a family of "small round structured" viruses, members of Class IV of the Baltimore scheme. Caliciviridae bear resemblance to enlarged picornavirus and was formerly a separate genus within the picornaviridae. They are p ...
''.


''Rabbit hemorrhagic disease virus''

''Rabbit hemorrhagic disease virus'' (RHDV) is a virus in the genus ''Lagovirus'' and the family ''Caliciviridae''. It is a nonenveloped virus with a diameter around 35–40 nm, icosahedral symmetry, and a linear positive-sense RNA genome of 6.4–8.5 kb. RHDV causes a generalized infection in rabbits that is characterized by liver necrosis, disseminated intravascular coagulation, and rapid death. Division into serotypes has been defined by a lack of cross-neutralization using specific antisera. Rabbit lagoviruses also include related caliciviruses such as ''European brown hare syndrome virus''. RHDV appears to have evolved from a pre-existing avirulent rabbit calicivirus (RCV). Nonpathogenic rabbit caliciviruses related to, but distinct from RHDV, had been circulating, apparently harmlessly, in Europe, Australia, and New Zealand prior to the emergence of RHDV. In the course of its evolution RHDV split into six distinct genotypes, all of which are highly pathogenic. The three strains of ''rabbit hemorrhagic disease virus'' of medical significance are RHDV, RHDVa and RHDV2. RHDV (also referred to as RHDV, RHDV1, or as classical RHD) only affects adult European rabbits (''Oryctolagus cuniculus''). This virus was first reported in China in 1984, from which it spread to much of Asia, Europe, Australia, and elsewhere. A few isolated outbreaks of RHDV have occurred in the United States and Mexico, but they remained localized and were eradicated. In 2010, a new lagovirus with a distinct antigenic profile was identified in France. The new virus, named ' (abbreviated as RHDV2 or RHDVb), also caused RHD, but exhibited distinctive genetic, antigenic, and pathogenic features. Importantly, RHDV2 killed rabbits previously vaccinated with RHDV vaccines, and affected young European rabbits, as well as hares (''Lepus'' spp.). All these features strongly suggest that the virus was not derived from RHDVa, but from some other unknown source. RHDV2 has since spread to the majority of Europe, as well as to Australia, Canada, and the United States.


Epidemiology and transmission

Both viruses causing RHD are extremely contagious. Transmission occurs by direct contact with infected animals, carcasses, bodily fluids (urine, feces, respiratory secretions), and hair. Surviving rabbits may be contagious for up to 2 months. Contaminated fomites such as clothing, food, cages, bedding, feeders, and water also spread the virus. Flies, fleas, and mosquitoes can carry the virus between rabbits. Predators and scavengers can also spread the virus by shedding it in their feces. Caliciviruses are highly resistant in the environment, and can survive freezing for prolonged periods. The virus can persist in infected meat for months, and for prolonged periods in decomposing carcasses. Importation of rabbit meat may be a major contributor in the spread of the virus to new geographic regions. RHD outbreaks tend to be seasonal in wild rabbit populations, where most adults have survived infection and are immune. As young kits grow up and stop nursing, they no longer receive the antibodies provided in their mother's milk and become susceptible to infection. Thus, RHD
epizootic In epizoology, an epizootic (from Greek: ''epi-'' upon + ''zoon'' animal) is a disease event in a nonhuman animal population analogous to an epidemic in humans. An epizootic may be restricted to a specific locale (an "outbreak"), general (an "epi ...
s occur more often during the rabbits' breeding season. Generally, high host specificity exists among lagoviruses. Classic RHDVa only affects European rabbits, a species native to Europe and from which the domestic rabbit is descended. The new variant RHDV2 affects European rabbits, as well, but also causes fatal RHD in various ''Lepus'' species, including Sardinian Cape hares (''L. capensis mediterraneus''), Italian hares (''L. corsicanus''), and mountain hares (''L. timidus''). Reports of RHD in ''Sylvilagus'' species have been coming from the current outbreak in the United States. RHD caused by RHDV and RHDVa demonstrates high morbidity (up to 100%) and mortality (40-100%) in adult European rabbits. Young rabbits 6–8 weeks old are less likely to be infected, and kits younger than 4 weeks old do not become ill. The more recently emerged RHDV2 causes death and disease in rabbits as young as 15 days old. Mortality rates from RHDV2 are more variable at 5-70%. Initially less virulent, the pathogenicity of RHDV2 has been increasing and is now similar to that found with RHDV and RHDVa. Deaths from RHDV2 have been confirmed in rabbits previously vaccinated against RHDVa.


Pathophysiology

These viruses replicate in the liver and by mechanisms not fully elucidated, trigger the mass death of
hepatocyte A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein synthesis * Protein storage * Transformation of carbohydrates * Synthesis of cholesterol, ...
s which can in turn lead to disseminated intravascular coagulation,
hepatic encephalopathy Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stages ...
, and
nephrosis Nephrosis is any of various forms of kidney disease (nephropathy). In an old and broad sense of the term, it is any nephropathy, but in current usage the term is usually restricted to a narrower sense of nephropathy without inflammation or neop ...
. Bleeding may occur, as clotting factors and platelets are used up.


Clinical signs

The incubation period for RHDVa is 1–2 days, and for RHDV2 3–5 days. Rabbits infected with RHDV2 are more likely to show subacute or chronic signs than are those infected with RHDVa. In rabbitries, an epidemic with high mortality rates in adult and subadult rabbits is typical. If the outbreak is caused by RHDV2, then deaths also occur in young rabbits. RHD can vary in the rate clinical signs occur. In peracute cases, rabbits are usually found dead with no premonitory symptoms. Rabbits may be observed grazing normally immediately before death. In acute cases, rabbits are inactive and reluctant to move. They may develop a fever up to 42 °C (107.6 °F) and have increased heart and respiratory rates. Bloody discharge from the nose, mouth, or vulva is common, as is blood in the feces or urine. Lateral recumbency, coma, and convulsions may be observed before death. Rabbits with the acute form generally die within 12 to 36 hours from the onset of fever. Subacute to chronic RHD has a more protracted clinical course, and is more commonly noted with RHDV2 infections. Clinical signs include lethargy, anorexia, weight loss, and
jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...
. Gastrointestinal dilation, cardiac
arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...
s,
heart murmur Heart murmurs are unique heart sounds produced when blood flows across a heart valve or blood vessel. This occurs when turbulent blood flow creates a sound loud enough to hear with a stethoscope. Turbulent blood flow is not smooth. The sound di ...
s, and neurologic abnormalities can also occur. Death, if it occurs, usually happens 1–2 weeks after the onset of symptoms, and is due to liver failure. Not all rabbits exposed to RHDVa or RHDV2 become overtly ill. A small proportion of infected rabbits clears the virus without developing signs of disease.
Asymptomatic carriers An asymptomatic carrier is a person or other organism that has become infection, infected with a pathogen, but shows no signs or symptoms. Although unaffected by the pathogen, carriers can transmit it to others or develop symptoms in later stage ...
also occur, and can continue to shed virus for months, thereby infecting other animals. Surviving rabbits develop a strong immunity to the specific viral variant with which they were infected.


Diagnosis

A presumptive diagnosis of RHD can often be made based on clinical presentation, infection pattern within a population, and ''post mortem'' lesions. Definitive diagnosis requires detection of the virus. As most caliciviruses cannot be grown in cell culture, antibody and nucleic acid based methods of viral detection are often used. Complete blood counts from rabbits with RHD often show low levels of white blood cells and platelets, and chemistry panels show elevated liver enzymes. Evidence of liver failure may also be present, including increased bile acids and bilirubin, and decreased glucose and cholesterol. Prolonged prothrombin and activated partial thromboplastin times are typical. Urinalysis can show bilirubinuria, proteinuria, and high urinary GGT. The classic ''post mortem'' lesion seen in rabbits with RHD is extensive hepatic necrosis. Multifocal hemorrhages, splenomegaly, bronchopneumonia, pulmonary hemorrhage or edema, and myocardial necrosis may sometimes also be seen.
RT-qPCR A real-time polymerase chain reaction (real-time PCR, or qPCR) is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR (i.e., in real ...
tests are a commonly used and accurate testing modality for RNA-based viruses. Other tests used include
enzyme-linked immunosorbent assay The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...
, electron microscopy,
immunostaining In biochemistry, immunostaining is any use of an antibody-based method to detect a specific protein in a sample. The term "immunostaining" was originally used to refer to the immunohistochemical staining of tissue sections, as first described by A ...
,
Western blot The western blot (sometimes called the protein immunoblot), or western blotting, is a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract. Besides detect ...
, and ''in situ'' hybridization. The tissue of choice for molecular testing is fresh or frozen liver, as it usually contains the largest numbers of virus, but if this is not available, spleen and serum can also be used. Identification of the strain of RHDV is needed so vaccination protocols can be adjusted accordingly.


Prevention and control


Vaccines

A number of vaccines available against RHD are sold in countries where the disease is endemic. All provide 12 months of protection against RHD viruses. Because RHD viruses cannot normally be grown ''
in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...
'', how these vaccines are produced is affected. Inactivated RHD vaccines, including Eravac, Felavac, and Cylap, are “liver-derived”, meaning that laboratory rabbits are intentionally infected with RHD and their livers and spleens harvested to make vaccines. Each rabbit used results in the production of thousands of vaccine doses. This has led to controversy among rabbit lovers, who question the ethics of some rabbits having to die to protect others but is not an issue where rabbits are primarily farmed for meat. Another method of reproducing the virus is through recombinant technology, where antigenic portions of the RHD viruses are inserted into viruses that can be grown in culture. This is the method used to create Nobivac Myxo-RHD PLUS. Vaccines against only the classic RHDVa strain are: Cylap RCD Vaccine, made by Zoetis, protects rabbits from two different strains of RHDVa (v351 and K5) that are used for wild rabbit control in Australia. CUNIPRAVAC RHD®, manufactured by
HIPRA HIPRA is a biotech pharmaceutical company focused on prevention for animal and human health, with a wide range of highly innovative vaccines and an advanced diagnostic service. With its headquarters in Catalonia, it is the world's fifth largest man ...
, protects against the RHDVa strains found in Europe. Nobivac Myxo-RHD, made by MSD Animal Health, is a live myxoma-vectored vaccine that offers one-year duration of immunity against both RHDVa and
myxomatosis Myxomatosis is a disease caused by ''Myxoma virus'', a poxvirus in the genus '' Leporipoxvirus''. The natural hosts are tapeti (''Sylvilagus brasiliensis'') in South and Central America, and brush rabbits (''Sylvilagus bachmani'') in North A ...
. Vaccines against only the newer RHDV2 strain are: Eravac vaccine, manufactured by HIPRA, protects rabbits against RHDV2 for a year. Vaccines that protect against both RHDVa and RHDV2 strains include: Filavac VHD K C+V, manufactured by Filavie, protects against both classical RHDVa and RHDV-2. It is available in single dose and multidose vials. A soon-to-be-released vaccine from MSD Animal Health, Nobivac Myxo-RHD PLUS, is a live recombinant vector vaccine active against both RHDVa and RHDV2, as well as myxomatosis. Countries in which RHD is not considered endemic may place restrictions on importation of RHDV vaccines. Importation of these vaccines into the United States can only be done with the approval of the
United States Department of Agriculture The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
and the appropriate state veterinarian.


Disinfection

Caliciviruses are stable in the environment and difficult to inactivate. Products commonly used for household disinfection such as Clorox® and Lysol® disinfecting wipes do not work against these viruses. One effective option is to wipe down surfaces with a 10% bleach solution, allowing 10 minutes of contact time before rinsing. Other disinfectants shown to work include 10%
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...
, 2% One-Stroke Environ®, Virkon® S, Clorox® Healthcare Bleach Germicidal Wipes, Trifectant®, Rescue®, and hydrogen peroxide cleaners. Surface debris must always be mechanically removed prior to disinfection. A list of disinfectants that are effective against calicivirus (in this case norovirus) can be found on the Environmental Protection Agency's website. Studies have show that many quaternary ammonium compound based disinfectants do not inactivate caliciviruses.


Quarantine and other measures

Because of the highly infectious nature of the disease, strict quarantine is necessary when outbreaks occur. Depopulation, disinfection, vaccination, surveillance, and quarantine are the only way to properly and effectively eradicate the disease. Deceased rabbits must be removed immediately and discarded in a safe manner. Surviving rabbits should be quarantined or humanely euthanized. Test rabbits may be used to monitor the virus on vaccinated farms.


Geographic distribution

RHD is primarily a disease affecting European rabbits, which are native to the
Iberian Peninsula The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula in southwestern Europe, defi ...
and are found in the wild in much of Western Europe. Domesticated breeds are farmed throughout the world for meat and fur, and are becoming increasingly popular pets. European rabbits have been introduced to and become
feral A feral () animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some ...
and sometimes invasive in Australia, New Zealand, Chile, Argentina, and various islands. RHD was first reported in 1984 in the People's Republic of China. Since then, RHD has spread to over 40 countries in Africa, the Americas, Asia, Europe, and
Oceania Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...
, and is endemic in most parts of the world.


Asia

The first reported outbreak of RHD caused by RHDVa occurred in 1984 in the Jiangsu Province of the
Mainland China "Mainland China" is a geopolitical term defined as the territory governed by the People's Republic of China (including islands like Hainan or Chongming), excluding dependent territories of the PRC, and other territories within Greater China. ...
. The outbreak occurred in a group of
Angora rabbit The Angora rabbit ( tr, Ankara tavşanı), which is one of the oldest types of domestic rabbit, is bred for the long fibers of its coat, known as ''Angora wool'', which are gathered by shearing, combing or plucking. Because rabbits do not possess ...
s that had been imported from
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
. The cause of the disease was determined to be a small, nonenveloped RNA virus. An inactivated vaccine was developed that proved effective in preventing disease. In less than a year, the disease spread over an area of 50,000 km2 in China and killed 140 million domestic rabbits.
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
was the next country to report RHD outbreaks following the importation of rabbit fur from Mainland China. RHD has since spread to and become endemic in many countries in Asia, including India and the Middle East.


Europe

From China, RHDVa spread westward to Europe. The first report of RHD in Europe came from in Italy in 1986. From there, it spread to much of Europe. Spain's first reported case was in 1988, and France, Belgium, and
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion#Europe, subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, ...
followed in 1990. Spain experienced a large die-off of wild rabbits, which in turn caused a population decline in predators that normally ate rabbits, including the
Iberian lynx The Iberian lynx (''Lynx pardinus'') is a wild cat species endemic to the Iberian Peninsula in southwestern Europe. It is listed as Endangered on the IUCN Red List. In the 20th century, the Iberian lynx population had declined because of overhun ...
and
Spanish imperial eagle The Spanish imperial eagle (''Aquila adalberti''), also known as the Spanish eagle or Adalbert's eagle, is a species of eagle native to the Iberian Peninsula. The binomial commemorates Prince Adalbert of Bavaria. Due to its distinct “epaulet ...
. RHD caused by RHDVa was reported for the first time in the United Kingdom in 1992. This initial epidemic was brought under control in the late 1990s using a combination of vaccination, strict biosecurity, and good husbandry. The newer viral strain RHDV2 was first detected in England and Wales in 2014, and soon spread to Scotland and Ireland. In 2010, a new virus variant called ''rabbit hemorrhagic disease virus 2'' (RHDV2) emerged in France. RHDV2 has since spread from France to the rest of Europe, Great Britain, Australia, and New Zealand. Outbreaks started occurring in the United States and Vancouver Island Canada in 2019. RHD was detected for the first time in Finland in 2016. The outbreak occurred in feral European rabbits, and genetic testing identified the viral strain as RHDV2. Cases of viral transmission to domesticated pet rabbits have been confirmed, and vaccinating rabbits has been recommended.


Oceania

In 1991, a strain of the RHDVa virus, Czech CAPM 351RHDV, was imported to Australia under strict
quarantine A quarantine is a restriction on the movement of people, animals and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been ...
conditions to research the safety and usefulness of the virus if it were used as a biological control agent against Australia and New Zealand's rabbit pest problem. Testing of the virus was undertaken on
Wardang Island Wardang Island, also known as Waralti (also spelled Waraldi or Wauraltee) is a low-lying 20 km2 island in the Spencer Gulf close to the western coast of the Yorke Peninsula, South Australia. It acts as a natural breakwater, protecting the f ...
in Spencer Gulf off the coast of the
Yorke Peninsula The Yorke Peninsula is a peninsula located northwest and west of Adelaide in South Australia, between Spencer Gulf on the west and Gulf St Vincent on the east. The peninsula is separated from Kangaroo Island to the south by Investigator Str ...
,
South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
. In 1995, the virus escaped quarantine and subsequently killed 10 million rabbits within 8 weeks of its release. In March 2017, a new Korean strain known as RHDV K5 was successfully released in a deliberate manner after almost a decade of research. This strain was chosen in part because it functions better in cool, wet regions where the previous ''Calicivirus'' was less effective. In July 1997, after considering over 800 public submissions, the
New Zealand Ministry of Health The Ministry of Health (Māori: ''Manatū Hauora'') is the public service department of New Zealand responsible for healthcare in New Zealand. It came into existence in its current form in 1993. History Origins The Ministry of Health's origin ...
decided not to allow RHDVa to be imported into New Zealand to control rabbit populations. However, in late August, RHDVa was confirmed to have been deliberately and illegally introduced to the
Cromwell Oliver Cromwell (25 April 15993 September 1658) was an English politician and military officer who is widely regarded as one of the most important statesmen in English history. He came to prominence during the 1639 to 1651 Wars of the Three Ki ...
area of the
South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...
. An unsuccessful attempt was made by New Zealand officials to control the spread of the disease. It was, however, being intentionally spread, and several farmers (notably in the
Mackenzie Basin The Mackenzie Basin (), popularly and traditionally known as the Mackenzie Country, is an elliptical intermontane basin located in the Mackenzie and Waitaki Districts, near the centre of the South Island of New Zealand. It is the largest su ...
area) admitted to processing rabbits that had died from the disease in kitchen blenders for further spreading. Had the disease been introduced at a better time, control of the population would have been more effective, but it was released after breeding had commenced for the season, and rabbits under 2 weeks old at the time of the introduction were resistant to the disease. These young rabbits were, therefore, able to survive and breed rabbit numbers back up. Ten years on, rabbit populations (in the Mackenzie Basin in particular) are beginning to reach near preplague proportions once again, though they have not yet returned to pre-RHD levels. Resistance to RHD in New Zealand rabbits has led to the widespread use of Compound 1080 (Sodium fluoroacetate). The government and department of conservation are having to increase their use of 1080 to protect reserve land from rabbits and preserve the gains made in recent years through the use of RHD.


North and South America

Isolated outbreaks of RHDVa in domestic rabbits have occurred in the United States, the first of which was in Iowa in 2000. In 2001, outbreaks occurred in Utah, Illinois, and New York. More recent outbreaks of RHDVa have occurred in 2005 in Indiana and 2018 in Pennsylvania. Each of these outbreaks was contained and was the result of separate but indeterminable introductions of RHDVa. RHDVa does not affect the native cottontail and jackrabbits in the United States, so the virus did not become endemic. The first report of RHDV2 virus in North America was on a farm in Québec, in 2016. In 2018, a larger outbreak occurred in feral European rabbits on Delta and Vancouver Island, British Columbia. The disease was confirmed later that year in a pet rabbit in Ohio. In July 2019, the first case of RHDV2 in Washington was confirmed in a pet rabbit from
Orcas Island Orcas Island () is the largest of the San Juan Islands of the Pacific Northwest, which are in the northwestern corner of San Juan County, Washington. History and naming of the island The name "Orcas" is a shortened form of ''Horcasitas,'' fro ...
. RHDV2 have been reported in domestic rabbits in Washington and New York. In 2020, outbreaks of the disease in domestic rabbits, as well as cottontail rabbits and hares, have been reported in Arizona, New Mexico, Colorado, Texas, Nevada, California and Utah. Affected wildlife include
mountain cottontail The mountain cottontail or Nuttall's cottontail (''Sylvilagus nuttallii'') is a species of mammal in the family Leporidae. It is found in Canada and the United States. Description The mountain cottontail is a small rabbit but its size is rel ...
rabbits (''Sylvilagus nutalli''),
desert cottontail The desert cottontail (''Sylvilagus audubonii''), also known as Audubon's cottontail, is a New World cottontail rabbit, and a member of the family Leporidae. Unlike the European rabbit (''Oryctolagus cuniculus''), they do not form social burrow s ...
rabbits (''S. audubonii''),
antelope jackrabbit The antelope jackrabbit (''Lepus alleni'') is a species of North American hare found in southern Arizona and northwestern Mexico that occupies dry desert areas. Behaviour It is most active during twilight ( crepuscular) and during the night ( no ...
s (''L. alleni''), and
black-tailed jackrabbits The black-tailed jackrabbit (''Lepus californicus''), also known as the American desert hare, is a common hare of the western United States and Mexico, where it is found at elevations from sea level up to . Reaching a length around , and a ...
(''L. californicus''). The virus circulating in the Southwest United States is distinct from the RHDV2 isolated from New York, Washington, Ohio, and British Columbia, Canada. The sources of these outbreaks are unknown. In June 2022, a case occurred in Hawaii. It was first confirmed in a neutered hare on Maui. Department of Agriculture inspectors began testing after becoming aware of 9 rabbit deaths on a Maui farm. Mexico experienced an outbreak of RHDVa in domestic rabbits from 1989 to 1991, presumably following the importation of rabbit meat from the People's Republic of China. Strict quarantine and depopulation measures were able to eradicate the virus, and the country was officially declared to be RHD-free in 1993. A second outbreak of RHD in domestic rabbits began in the state of Chihuahua in April 2020 and has since spread to Sonora, Baja California, Baja California Sur, Coahuila, and Durango. Since 1993, RHDVa has been endemic in Cuba. Four epizootics involving domesticated rabbits were reported in 1993, 1997, 2000–2001, and 2004–2005. As consequence, thousands of rabbits have died or have been slaughtered each time. The virus is also believed to be thriving in
Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...
.


See also

*
Rabbits in Australia European rabbits (''Oryctolagus cuniculus'') were first introduced to Australia in the 18th century with the First Fleet, and later became widespread likely because of Thomas Austin. Such wild rabbit populations are a serious mammalian pest an ...


References

* New outbreak in Canada reported on Vancouver Island


External links


Disease card

RHDV2 in USA
{{DEFAULTSORT:Rabbit Haemorrhagic Disease Animal viral diseases Hemorrhagic fevers Rabbit diseases