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Q&A about the Rabbit Hemorrhagic Disease vaccine

  |   Animal Health

The following is information provided by Dr. Alice McLaughlin, veterinarian in Bothell, who imported the RHD2 vaccine for use in the quarantine and control areas of Washington. For additional questions about the vaccine or the virus after reading this, contact Dr. McLaughlin at 425-486-9000 or the Washington State Department of Agriculture. If any rabbit owners are interested in getting their rabbits vaccinated, please have contact Dr. McLaughlin as soon as possible to sign up for vaccine clinics or to get their rabbits on the vaccine waiting list.

1) Q: Were rabbits actually diagnosed with RHD2 in Washington State? How do vets know that this is the virus strain that has been causing the rabbit deaths?  Couldn’t the virus have mutated?

A: Yes, RHD2 was confirmed to be the cause of multiple rabbit deaths in Washington State from 2019-2020 in all 3 quarantine areas (San Juan Islands, Whidbey Island, and Clallam County – see detailed information here. The disease was identified as RHD2 following rt-PCR testing at the National Veterinary Laboratory of samples taken from deceased rabbits. The state veterinarian’s office made an effort to test every deceased animal suspected of dying from RHD2, and all of the rabbit deaths attributed to the disease by the state veterinarian’s office had positive rt-PCR tests for RHD2. The same genotype was identified in all of the positive tests (i.e., there are NOT multiple strains or mutated strains present). There may have been other deaths from RHD2 that did not have positive tests for various reasons, and there are probably rabbits that survived the disease and are still in the feral rabbit population. Regardless, the disease is definitely here.

2) Q: What type of vaccine was imported?  Is it possible for vaccinated animals to become carriers and infect non-vaccinated animals?

A: The vaccine that the Center for Bird and Exotic Animal Medicine (CBEAM) has imported is Filavac, which protects against both RHD1 and RHD2. Follow this link to see the data sheet for the vaccine.

Filavac is a killed vaccine, meaning that there is zero chance that vaccinated animals can either contract the disease or spread it to others. Vaccinated rabbits will not infect non-vaccinated animals, and they do NOT become carriers of the disease.

However, rabbits surviving a natural infection with RHD2 are believed to shed the virus for at least 30 days, potentially up to 105 days. For more information, see the WSDA Rabbit Hemorrhagic Disease Fact Sheet.

3) Q: How do we know that the imported Filavac vaccine will be effective against this strain of the virus?

A: The Filavac vaccine is specifically developed for use against RHD2. It has been proven safe and effective in protecting rabbits from this disease. Here is a link to a paper looking at protective nature of Filavac vaccine against a wild-type strain of RHD2 in France (the same genotype as the virus identified in WA). In this study, all but one of the unvaccinated rabbits died following exposure to the disease, while all of the vaccinated rabbits remained healthy.

4) Q: If the vaccine has to be administered annually, what’s the point of vaccinating my rabbits when there is no guarantee that additional vaccines will be permitted to be imported next year?

A: The vaccine is licensed overseas to be effective for at LEAST one year for 90% of vaccinated animals (some rabbits had immunity for 18 months according to Morin et al, 2015 in Journées de la Recherche Cunicole), and it is possible that protective immunity will persist for longer than that in some individuals. While we don’t know for certain if importation of the vaccine will be permitted next year, we do have a very high level of suspicion that this disease is going to remain in WA state and continue to infect both feral rabbits and domestic rabbits. The best way to try to protect your rabbits from this deadly disease is to get them vaccinated. Even if the vaccinated rabbits contract the disease after their immunity decreases, they might have a lower risk of fatality from it, as their immune system would have a jump start on recognizing the organism.

5) Q: Since so many feral rabbits have already died from RHD2, won’t the virus just eventually “die out” in WA state?

A: No. The state veterinarian’s office suspects that RHD2 spread here originally from scavenging birds traveling from Canada to the San Juan Islands; there is no way to prevent spread of disease via birds. The virus is also very stable in the environment, potentially surviving for more than three months without a host. It can also be spread by flies. This virus is unfortunately likely to become endemic to WA state. Here is a link to some additional information about RHD:

CBEAM has also received a number of complaints about vaccine prices. The costs, legal challenges, and time involved in importing this vaccine were astronomical, and to their knowledge, they are the only veterinary clinic to successfully import the vaccine so far. Most other veterinarians have stopped trying to obtain the vaccine due to the expense and legal/logistical barriers, although Dr. McLaughlin has personally tried to help several vets who expressed interest in importation. Between international shipping, hiring a private broker, and the costs of the vaccines themselves, CBEAM paid many thousands of dollars to import the vaccines. In addition to Dr. McLaughlin’s personal time, there are associated costs involved in setting up the vaccine clinics; including paying their technician and maintaining proper biosecurity, medical records, travel, and other factors.

This information has not been verified by the WSVMA and is providing it as a service to rabbit owners.

 

Posted February 14, 2020