New RHDV2 vaccine for rabbits authorized
The State Veterinarian’s Office has authorized use of a new vaccine for RHDV2, developed by Medgene Labs of South Dakota. It is a 2-dose regimen with a booster in 21 days. Only a Washington-licensed veterinarian can administer the vaccine. Veterinarians should contact Medgene at medgenelabs.com or (605) 697-2600 to order the vaccine.
Common questions about rabbit hemorrhagic disease
Where did the virus come from?
The RHD virus was first detected in China in the winter of 1983-84. Outbreaks occur periodically throughout the world and continually in some countries but have been quite rare in North America. In the U.S., sporadic cases have occurred in nine states between 2000 and 2019; British Columbia experienced outbreaks in 2018-2019, primarily on Vancouver Island. Given proximity, ferry traffic, bird migration, wind patterns, and human activity, it is plausible the San Juan Island cases are connected to the ongoing British Columbia outbreak.
Will the virus be here from now on?
The presence of feral domestic rabbits on the islands complicates the situation. It is difficult to control and eliminate diseases that can be spread and maintained in wildlife populations. Perhaps RHD will manifest as periodic die offs of feral domestic rabbit populations. The USDA now considers RHD a “regionally endemic” disease, meaning it is established in certain geographic zones. Those who own rabbits and live in affected areas should just plan on enacting recommended biosecurity practices from here on and consider vaccinating.
What are the differences between the different RHD virus types?
There are many strains of the RHD virus, but three are of most concern. RHD Type 1 has two forms, RHDV and RHDVa. RHD Type 2 has just one form, RHDV2. The two forms of Type 1 are quite similar and their vaccines are cross-protective. They tend to not affect young bunnies but have a very high mortality rate for adult rabbits. RHDV2, on the other hand, seems less deadly than the Type 1 strains, but affects all ages of rabbits. The RHDV2 vaccine only protects against that type.
Is it true Eastern Cottontails are susceptible to the RHDV2 strain of virus?
Experimentally, Eastern cottontails are susceptible to certain strains of RHDV2. However, we have had no reports of cottontail mortalities associated with RHDV during this outbreak. WA Department of Fish and Wildlife is monitoring the situation.
How many cases of RHD have been confirmed in WA?
Four premises with owned domestic rabbits have been confirmed positive for RHD to date. Three were on Orcas Island and one was on San Juan Island. We have had no reports of sickness in owned domestic rabbits on Whidbey or Lopez Islands, just feral domestics. Many domestic rabbits died in Clallam County between late December 2019 and mid-January 2020; we had not had any confirmed cases since then.
WSDA tested dead rabbits from several other western Washington counties and all werel negative for RHD. We appreciate being contacted by concerned citizens regarding sick or dead wild or feral domestic rabbits and will pursue a diagnosis if these rabbits are found in an area where RHD has not yet been diagnosed. WSDA will follow up on all cases of reported domestic rabbit mortalities.
How is RHD transmitted?
Rabbit hemorrhagic disease spreads between rabbits mostly by ingestion or inhalation of the virus. The virus is present in urine and feces from infected rabbits, so contaminated bedding, food, or forage can be a source of infection. The virus can be moved from place to place by flies, predators, scavengers, wild rabbits, vehicle tires, clothing, footwear, equipment, and wind and water movement.
How long can RHD persist in the environment?
The virus can survive for long periods outside the host. Environmental temperature and protection by organic material are important factors in the survival of the virus. Viable virus has been detected for as long as 105 days on a fomite at room temperature, has been found in decaying tissue of infected carcasses for up to 90 days, and may persist in chilled or frozen rabbit meat. The virus can remain viable for 22 to 35 days at 72°F, which is average highs for NW summers. It also survives freeze-thaw cycles.
Can rabbits that have been exposed and recover or never become ill become carriers of the virus for life?
Variable mortality rates have been reported in WA ranging from 33 to 74%. Exposure to a virus does not mean infected with a virus. Some rabbits will just be exposed; others will be exposed and become infected and either die or recover. Infected rabbits will shed the virus for weeks to months. Surviving rabbits will develop antibodies to the virus and become resistant to related calicivirus strains. They will probably be able to be reinfected after their antibody protection wanes.
Does WSDA depopulate domestic colonies that have had confirmed cases of RHD?
WSDA will not depopulate domestic, feral, or wild rabbit colonies where rabbits have been exposed and recovered from RHD. RHD is in the feral domestic population, which makes it impossible to know which rabbitries have been infected or exposed. Depopulation will do little to control the disease because the virus is present in the wild rabbit population in affected areas. WSDA and USDA also have no funding for indemnity to reimburse rabbit owners for their losses.
Why doesn’t WSDA depopulate the feral domestic population?
WSDA does not have the resources to depopulate all feral domestic rabbits. In addition, this population is classified as an invasive species and non-native to the area. Neither WSDA nor the Washington Department of Fish and Wildlife has authority to control non-native feral domestic rabbits.
How can I tell if my rabbit has RHD?
Only laboratory tests can confirm an RHD diagnosis. However, RHD should be considered if a rabbitry experiences illness in most/all rabbits, high fevers, poor appetites, depression, inactivity, bloody discharges, and/or sudden death. Call your veterinarian right away if you have any concerns about your rabbit’s health.
What should I do if I find a dead rabbit?
If an owned rabbit dies and RHD could be the cause, double bag the body in plastic bags and refrigerate it until given more instructions. Do not freeze it. Contact the WSDA at (360) 902-1878 or ahealth@agr.wa.gov for more information. If you find a dead feral domestic or wild rabbit, contact the WSDA to determine whether or not this carcass should be submitted for testing. Always wear disposable gloves when handling a dead animal; dispose of them when done and wash your hands.
Can humans, dogs or other animals contract RHD?
RHD is not a zoonotic disease and there is no public health significance. RHD is specific to rabbits. Dogs, cats and other pets cannot contract the disease, but may act as carriers like vehicles, shoes and equipment can.
What about the cases in the southwestern U.S.?
A large RHD outbreak began in the southwestern U.S. in 2020 and has killed thousands of rabbits in New Mexico, Arizona, Texas, Colorado, Nevada, California and Utah. Unlike the Washington State and British Columbia outbreaks, the southwestern U.S. outbreak has affected both domestic and wild rabbit species. Analysis of the virus revealed it is an RHDV2 virus strain different from the northern U.S./British Columbia strain but the same as a strain active in Mexico.
The RHD virus was first detected in China in the winter of 1983-84. Outbreaks occur periodically throughout the world and continually in some countries but have been quite rare in North America. In the U.S., sporadic cases have occurred in nine states between 2000 and 2019; British Columbia experienced outbreaks in 2018-2019, primarily on Vancouver Island. Given proximity, ferry traffic, bird migration, wind patterns, and human activity, it is plausible the San Juan Island cases are connected to the ongoing British Columbia outbreak.
Will the virus be here from now on?
The presence of feral domestic rabbits on the islands complicates the situation. It is difficult to control and eliminate diseases that can be spread and maintained in wildlife populations. Perhaps RHD will manifest as periodic die offs of feral domestic rabbit populations. The USDA now considers RHD a “regionally endemic” disease, meaning it is established in certain geographic zones. Those who own rabbits and live in affected areas should just plan on enacting recommended biosecurity practices from here on and consider vaccinating.
What are the differences between the different RHD virus types?
There are many strains of the RHD virus, but three are of most concern. RHD Type 1 has two forms, RHDV and RHDVa. RHD Type 2 has just one form, RHDV2. The two forms of Type 1 are quite similar and their vaccines are cross-protective. They tend to not affect young bunnies but have a very high mortality rate for adult rabbits. RHDV2, on the other hand, seems less deadly than the Type 1 strains, but affects all ages of rabbits. The RHDV2 vaccine only protects against that type.
Is it true Eastern Cottontails are susceptible to the RHDV2 strain of virus?
Experimentally, Eastern cottontails are susceptible to certain strains of RHDV2. However, we have had no reports of cottontail mortalities associated with RHDV during this outbreak. WA Department of Fish and Wildlife is monitoring the situation.
How many cases of RHD have been confirmed in WA?
Four premises with owned domestic rabbits have been confirmed positive for RHD to date. Three were on Orcas Island and one was on San Juan Island. We have had no reports of sickness in owned domestic rabbits on Whidbey or Lopez Islands, just feral domestics. Many domestic rabbits died in Clallam County between late December 2019 and mid-January 2020; we had not had any confirmed cases since then.
WSDA tested dead rabbits from several other western Washington counties and all werel negative for RHD. We appreciate being contacted by concerned citizens regarding sick or dead wild or feral domestic rabbits and will pursue a diagnosis if these rabbits are found in an area where RHD has not yet been diagnosed. WSDA will follow up on all cases of reported domestic rabbit mortalities.
How is RHD transmitted?
Rabbit hemorrhagic disease spreads between rabbits mostly by ingestion or inhalation of the virus. The virus is present in urine and feces from infected rabbits, so contaminated bedding, food, or forage can be a source of infection. The virus can be moved from place to place by flies, predators, scavengers, wild rabbits, vehicle tires, clothing, footwear, equipment, and wind and water movement.
How long can RHD persist in the environment?
The virus can survive for long periods outside the host. Environmental temperature and protection by organic material are important factors in the survival of the virus. Viable virus has been detected for as long as 105 days on a fomite at room temperature, has been found in decaying tissue of infected carcasses for up to 90 days, and may persist in chilled or frozen rabbit meat. The virus can remain viable for 22 to 35 days at 72°F, which is average highs for NW summers. It also survives freeze-thaw cycles.
Can rabbits that have been exposed and recover or never become ill become carriers of the virus for life?
Variable mortality rates have been reported in WA ranging from 33 to 74%. Exposure to a virus does not mean infected with a virus. Some rabbits will just be exposed; others will be exposed and become infected and either die or recover. Infected rabbits will shed the virus for weeks to months. Surviving rabbits will develop antibodies to the virus and become resistant to related calicivirus strains. They will probably be able to be reinfected after their antibody protection wanes.
Does WSDA depopulate domestic colonies that have had confirmed cases of RHD?
WSDA will not depopulate domestic, feral, or wild rabbit colonies where rabbits have been exposed and recovered from RHD. RHD is in the feral domestic population, which makes it impossible to know which rabbitries have been infected or exposed. Depopulation will do little to control the disease because the virus is present in the wild rabbit population in affected areas. WSDA and USDA also have no funding for indemnity to reimburse rabbit owners for their losses.
Why doesn’t WSDA depopulate the feral domestic population?
WSDA does not have the resources to depopulate all feral domestic rabbits. In addition, this population is classified as an invasive species and non-native to the area. Neither WSDA nor the Washington Department of Fish and Wildlife has authority to control non-native feral domestic rabbits.
How can I tell if my rabbit has RHD?
Only laboratory tests can confirm an RHD diagnosis. However, RHD should be considered if a rabbitry experiences illness in most/all rabbits, high fevers, poor appetites, depression, inactivity, bloody discharges, and/or sudden death. Call your veterinarian right away if you have any concerns about your rabbit’s health.
What should I do if I find a dead rabbit?
If an owned rabbit dies and RHD could be the cause, double bag the body in plastic bags and refrigerate it until given more instructions. Do not freeze it. Contact the WSDA at (360) 902-1878 or ahealth@agr.wa.gov for more information. If you find a dead feral domestic or wild rabbit, contact the WSDA to determine whether or not this carcass should be submitted for testing. Always wear disposable gloves when handling a dead animal; dispose of them when done and wash your hands.
Can humans, dogs or other animals contract RHD?
RHD is not a zoonotic disease and there is no public health significance. RHD is specific to rabbits. Dogs, cats and other pets cannot contract the disease, but may act as carriers like vehicles, shoes and equipment can.
What about the cases in the southwestern U.S.?
A large RHD outbreak began in the southwestern U.S. in 2020 and has killed thousands of rabbits in New Mexico, Arizona, Texas, Colorado, Nevada, California and Utah. Unlike the Washington State and British Columbia outbreaks, the southwestern U.S. outbreak has affected both domestic and wild rabbit species. Analysis of the virus revealed it is an RHDV2 virus strain different from the northern U.S./British Columbia strain but the same as a strain active in Mexico.
More on Biosecurity and Showing Rabbits
How should I clean and disinfect cages, etc.?
Remove all visible debris from items to be disinfected (cages, feeding equipment, waterers, etc.). Items made of wood are best discarded. Wash thoroughly with soap and water; rinse well and let dry. Submerge or saturate with spray or 10% household bleach solution (1 part bleach to 9 parts water). Allow 10 minutes of contact, then rinse and let dry before allowing animal contact.
The RHD calicivirus is inactivated by 10 minutes of exposure to:
What should we do about large rabbit gatherings like ARBA rabbit shows, 4-H rabbit shows, and fairs?
Show/fair management will need to establish policies for exhibitors who wish to attend their show. It is up to each rabbit show’s management to evaluate their risks and decide what parameters they would like to establish and enforce.
Should rabbit owners consider not bringing rabbits to meetings for biosecurity reasons?
Rabbit meetings with live rabbits can contradict quite a few of the biosecurity check-list items. Biosecurity practices are always a good idea, not just for RHD, but more common contagious conditions such as Pasteurella, mites, etc. Counties on the mainland are considered relatively low risk for RHD at this time. The highest risk areas are those with infected feral domestic rabbits (the four aforementioned islands). Indoor rabbits cared for with excellent biosecurity practices are at very low risk.
Rabbits co-mingled at club meetings or shows have greater risk of contracting snuffles from an infected rabbit compared to RHD. Risk of disease transmission could be reduced at club meetings by only having rabbits from one premise present per meeting.
All club members must wash hands before and after handling the rabbit(s) and arrive at the meeting site with clean clothing and clean/disinfected footwear. After returning home, they should change clothes and footwear and wash their hands before caring for their own rabbits. We all have different levels of risk we are willing to accept; the most conservative will not take animals away from home or allow them to contact other animals. Not every 4-Her is required to show his/her animal if they do not want to for whatever reason.
What biosecurity recommendations should I familiarize myself with?
Rabbit owners should familiarize themselves with the WSDA’s recommendations and enact the following biosecurity measures from here on:
Remove all visible debris from items to be disinfected (cages, feeding equipment, waterers, etc.). Items made of wood are best discarded. Wash thoroughly with soap and water; rinse well and let dry. Submerge or saturate with spray or 10% household bleach solution (1 part bleach to 9 parts water). Allow 10 minutes of contact, then rinse and let dry before allowing animal contact.
The RHD calicivirus is inactivated by 10 minutes of exposure to:
- Household bleach (sodium hypochlorite) at 1:10 dilution
- 1% Virkon-S (by DuPont)
- Sodium hydroxide (1%)
- Beta-propiolactone 0.2–0.5%
- Chlorine dioxide at 10 ppm concentration
- 2% One-stroke Environ® (Vestal Lab Inc., St. Louis, MO)
What should we do about large rabbit gatherings like ARBA rabbit shows, 4-H rabbit shows, and fairs?
Show/fair management will need to establish policies for exhibitors who wish to attend their show. It is up to each rabbit show’s management to evaluate their risks and decide what parameters they would like to establish and enforce.
Should rabbit owners consider not bringing rabbits to meetings for biosecurity reasons?
Rabbit meetings with live rabbits can contradict quite a few of the biosecurity check-list items. Biosecurity practices are always a good idea, not just for RHD, but more common contagious conditions such as Pasteurella, mites, etc. Counties on the mainland are considered relatively low risk for RHD at this time. The highest risk areas are those with infected feral domestic rabbits (the four aforementioned islands). Indoor rabbits cared for with excellent biosecurity practices are at very low risk.
Rabbits co-mingled at club meetings or shows have greater risk of contracting snuffles from an infected rabbit compared to RHD. Risk of disease transmission could be reduced at club meetings by only having rabbits from one premise present per meeting.
All club members must wash hands before and after handling the rabbit(s) and arrive at the meeting site with clean clothing and clean/disinfected footwear. After returning home, they should change clothes and footwear and wash their hands before caring for their own rabbits. We all have different levels of risk we are willing to accept; the most conservative will not take animals away from home or allow them to contact other animals. Not every 4-Her is required to show his/her animal if they do not want to for whatever reason.
What biosecurity recommendations should I familiarize myself with?
Rabbit owners should familiarize themselves with the WSDA’s recommendations and enact the following biosecurity measures from here on:
- Keep rabbits inside if possible.
- Have indoor and outdoor footwear; don’t wear outdoor shoes indoors and vice versa.
- Wash hands before and after handling or caring for rabbits.
- Clean and disinfect feeders and other equipment daily if possible. Clean with soap and water, rinse well, spray with or submerge in 10% bleach for 10 minutes, rinse well, and let dry before re-use.
- Control flies, rats, cats, dogs, birds, etc. that can move the virus around on their feet or body.
- Don't allow visitors who also have rabbits.
- Prevent contact with wild rabbits.
- Do not put rabbits down on the ground to eat grass, etc.
- Do not collect outdoor forage and browse to feed rabbits; stay with pelleted feed for now. Treats can include raw vegetables from grocery stores.
- Don't handle others' rabbits.
- Monitor your rabbits closely for going off feed, looking limp/depressed, or behaving differently in any way. This viral form (RHDV2) is less fatal than the two other versions, so treatment may be successful if started right away. Call your vet ASAP if you note signs of illness in your rabbit.
- Report all unusual mass morbidity (sickness) or mortality (death) events to WSDA.
- Subscribe to updates from the WSDA email list.
Common Questions about Vaccine
RABBIT HEMORRHAGIC DISEASE VACCINE
A vaccine has been developed by Medgene Labs of South Dakota. Their product is an inactivated (killed) recombinant subunit vaccine that builds immunity to RHDV2-specific antigenic proteins in the rabbit. Unlike the Eravac and Filavac vaccines imported from Europe, the Medgene product does not depend on live rabbits for its production and Medgene vaccinated rabbits can be differentiated from infected rabbits on a laboratory PCR test.
LEARN MORE
Is a vaccine available?
Yes, but under emergency and conditional approval with the USDA Center of Veterinary Biologics. While in this status, the vaccine can only be administered by a Washington-licensed veterinarian. The vaccine is administered as a subcutaneous injection and is a 2-dose regimen, with the booster dose being delivered 21 days following the first. Established vaccine withdrawal periods (21 days) must be followed for meat-type rabbits used for human or animal consumption.
Veterinarians who would like to order the Medgene vaccine should contact Medgene labs directly at medgenelabs.com or by calling (605) 697-2600. Veterinarians should maintain vaccination records as for any routine vaccination and conforming to state licensure expectations. Meat-type rabbits vaccination records may be kept at the herd level, similar to other livestock, rather than at the individual animal level.
Commercial RHD vaccines are also manufactured in France and Spain but not currently authorized for manufacture or widespread use in the U.S. During outbreaks, however, the USDA can issue licenses to private veterinarians to import the vaccine if these veterinarians complete a federal application process. Three veterinarians in western Washington State have received one-year licenses permitting them to import and administer the vaccines from Europe. This vaccine is only approved for use in rabbits in or near the western Washington outbreak areas. The vaccine is killed and will NOT cause RHD; it will stimulate vaccinated animals to produce protective antibodies against RHDV2, thereby preventing illness. The immunity is short-lived, though, and booster vaccinations should be given every 6 to 12 months.
Are vaccinated rabbits considered “infected” and shedding virus for life?
The RHDV vaccine is a killed vaccine and rabbits will not shed live virus after vaccination. If vaccinated rabbits are tested for antibodies by the ELISA laboratory test, antibodies to the vaccine will be detected. In the U.S., the only test available to detect viral DNA is PCR. The PCR test cannot be performed for live animals. This test is only available at the Foreign Animal Disease Diagnostic Lab on Plum Island, NY, because RHD is a foreign animal disease.
Can vaccinated rabbits infect other rabbits after vaccination through their saliva?
No. Killed vaccines are inactivated, so there’s no chance of the vaccine causing disease spread to other rabbits via saliva, feces, hair, etc. However, vaccinated or unvaccinated rabbits can passively carry the virus on their feet, hair, whiskers, etc. and move it that way, just as with human feet, car tires, shovels, etc.
Where can I get my rabbits vaccinated?
Private veterinarians who apply to import the vaccine through the USDA or those who obtain the Medgene vaccine can administer it. Contact your veterinarian to see if they have gone through the important process or acquired the Medgene vaccine.
A vaccine has been developed by Medgene Labs of South Dakota. Their product is an inactivated (killed) recombinant subunit vaccine that builds immunity to RHDV2-specific antigenic proteins in the rabbit. Unlike the Eravac and Filavac vaccines imported from Europe, the Medgene product does not depend on live rabbits for its production and Medgene vaccinated rabbits can be differentiated from infected rabbits on a laboratory PCR test.
LEARN MORE
Is a vaccine available?
Yes, but under emergency and conditional approval with the USDA Center of Veterinary Biologics. While in this status, the vaccine can only be administered by a Washington-licensed veterinarian. The vaccine is administered as a subcutaneous injection and is a 2-dose regimen, with the booster dose being delivered 21 days following the first. Established vaccine withdrawal periods (21 days) must be followed for meat-type rabbits used for human or animal consumption.
Veterinarians who would like to order the Medgene vaccine should contact Medgene labs directly at medgenelabs.com or by calling (605) 697-2600. Veterinarians should maintain vaccination records as for any routine vaccination and conforming to state licensure expectations. Meat-type rabbits vaccination records may be kept at the herd level, similar to other livestock, rather than at the individual animal level.
Commercial RHD vaccines are also manufactured in France and Spain but not currently authorized for manufacture or widespread use in the U.S. During outbreaks, however, the USDA can issue licenses to private veterinarians to import the vaccine if these veterinarians complete a federal application process. Three veterinarians in western Washington State have received one-year licenses permitting them to import and administer the vaccines from Europe. This vaccine is only approved for use in rabbits in or near the western Washington outbreak areas. The vaccine is killed and will NOT cause RHD; it will stimulate vaccinated animals to produce protective antibodies against RHDV2, thereby preventing illness. The immunity is short-lived, though, and booster vaccinations should be given every 6 to 12 months.
Are vaccinated rabbits considered “infected” and shedding virus for life?
The RHDV vaccine is a killed vaccine and rabbits will not shed live virus after vaccination. If vaccinated rabbits are tested for antibodies by the ELISA laboratory test, antibodies to the vaccine will be detected. In the U.S., the only test available to detect viral DNA is PCR. The PCR test cannot be performed for live animals. This test is only available at the Foreign Animal Disease Diagnostic Lab on Plum Island, NY, because RHD is a foreign animal disease.
Can vaccinated rabbits infect other rabbits after vaccination through their saliva?
No. Killed vaccines are inactivated, so there’s no chance of the vaccine causing disease spread to other rabbits via saliva, feces, hair, etc. However, vaccinated or unvaccinated rabbits can passively carry the virus on their feet, hair, whiskers, etc. and move it that way, just as with human feet, car tires, shovels, etc.
Where can I get my rabbits vaccinated?
Private veterinarians who apply to import the vaccine through the USDA or those who obtain the Medgene vaccine can administer it. Contact your veterinarian to see if they have gone through the important process or acquired the Medgene vaccine.