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Calicivirus update

Our office in Bega has recently received a number of queries regarding Rabbit Haemorrhagic Disease Virus (RHDV), commonly known as calicivirus, from livestock producers interested in reducing rabbit numbers on their land, and from owners of pet or meat rabbits wanting to know how to best protect their animals from this disease.

RHDV

  • RHDV is a viral disease that affects rabbits (both wild and domestic). It damages the liver and interferes with clotting of blood. Affected rabbits typically die within one to two days after infection.
    It is spread primarily via direct contact between infected rabbits and by biting insects (eg. fleas, mosquitoes, flies)
  • A benign strain of the virus has been present in Australia for many years, but this strain does not cause disease in rabbits.
  • A more infective Czech strain (an RHDV-1 virus) was first introduced into Australia in the mid 1990s to reduce wild rabbit numbers. At the time, this was very effective.
  • Over time, the Czech strain has become less effective at reducing wild rabbit populations. Rabbits now need to be exposed to a much larger amount of the virus to become sick.
  • Earlier this year, a new virus (an RHDV-2 virus), which behaves in a very similar way to RHDV-1, was detected in Australia. RHDV-2 first appeared in France in 2010. There have been confirmed cases of RHDV-2 in central west Victoria, ACT, Orange, Goulburn and several locations along the east coast of Australia, including the Bega Valley. This virus was not released by Australian authorities.
  • Researchers have been looking into alternative strains of RHDV-1 to improve rabbit biocontrol. Application for the release of the Korean strain (K5) is underway and release is expected at some point during 2016-17 to assist the control of the wild rabbit population.
  • Further information will be circulated by the NSW Department of Primary Industries and Local Land Services prior to the release to ensure people are aware of how the release may affect them.

I'm a livestock producer. What does this mean for me?

For now, the best strategy for land managers is to continue using conventional methods of rabbit control such as poisoning, warren ripping, and follow-up fumigation of warrens to reduce rabbit populations. RHDV release (of the current Czech strain) can help to slow the rate of population recovery.

To discuss options for wild rabbit population control on your property, contact Jake Tanner, Senior Biosecurity Officer , South East Local Land Services, on 6491 7800.

I own pet/show/meat-producing rabbits. What does this mean for me?

  • Vaccination is one of the main options available to protect your rabbits. The good news is that the current calicivirus vaccine IS effective against the RHDV-1 strains of calicivirus - the Czech strain currently used and the yet-to-be released K5 strain.
  • The current recommendation is to vaccinate rabbits at two and a half to three months of age, then repeat annually. The vaccine label does allow for the use of the vaccine at a younger age where the local disease situation indicates.
  • The current vaccine is less effective against disease from RHDV-2. While there have been deaths recorded in vaccinated rabbits infected with this new virus, evidence indicates that vaccination does increase the chance of survival of infection with RHDV-2.
  • The suggested protocol to protect against RHDV-2 currently causing problems in the area is that kittens should be vaccinated at four weeks of age, with a booster given every four weeks until two and a half to three months of age, then annually. More valuable rabbits can be given boosters every six months as there has been an indication that the more vaccinations a rabbit has received the greater the immunity to the virus.
  • To discuss the best protocol for your rabbit, contact your local veterinary hospital.

Even if your rabbit is vaccinated, it is important to be vigilant with biosecurity. Avoid contact between your rabbit and wild rabbits, aim to prevent exposure to biting insects, contaminated feed (such as fresh feed collected from the paddock) and avoid situations that may cause stress (for example, high stocking densities in farmed meat-rabbit enterprises).