Inquiries came 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.

South East LLS district veterinarian Helen Schaefer said RHDV is a viral disease that affects wild and domestic rabbits.

“It damages the liver and interferes with clotting of blood,” Dr Schaefer said.

“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, for example fleas, mosquitoes and 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 introduced into Australia in the mid-1990s to reduce wild rabbit numbers.

“At the time, this was very effective,” Dr Schaefer said.

“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 and was not released by Australian authorities. 

There have been confirmed cases of RHDV-2 in central west Victoria, ACT, Orange, Goulburn and several locations along the eastern coast of Australia.

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 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,” Dr Schaefer said.

“For now, the best strategy for land managers dealing with wild rabbits is to continue using conventional methods of rabbit control such as poisoning, warren ripping, and follow-up fumigation of warrens to reduce rabbit populations.

“The RHDV release of the current Czech strain can help to slow the rate of population recovery.

“Vaccination is one of the main options available for pet and show rabbit owners and rabbit meat producers to protect their rabbits,” Dr Schaefer said. 

“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,” Dr Schaefer said.  

“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,” Dr Schaefer said. 

“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.”

Dr Schaefer said 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.

To discuss options for wild rabbit population control on your property, contact South East LLS senior biosecurity officer Jake Tanner on 6491 7800.

For further information about calicivirus  contact Dr Schaefer on 6491 7800.