Latest updates on calicivirus release sites in Tasmania can be found on the NRE Tas website: Tasmanian calicivirus release sites.
About Rabbit Haemorrhagic Disease Virus (RHDV)
European rabbits are an introduced pest species that thrives in Tasmanian conditions. Left unchecked, rabbit populations can rapidly increase, outcompeting native wildlife for food and habitat. Their excessive grazing habits often lead to soil erosion, reduced water quality and can degrade landscapes over time.
Biological control (where available) is an important component of holistic management of a pest species. Rabbit Haemorrhagic Disease Virus (RHDV1, also known as calicivirus) is a viral disease that is used to biologically control European rabbits. It was introduced into Australia in 1996 and Tasmania in 1997, and has since spread throughout most of Australia. It is one of the most humane and effective methods of biologically controlling wild rabbit populations - protecting native wildife and Tasmania's unique environment. When rabbit numbers increase and cause significant impact, Biosecurity Tasmania actively releases (when conditions permit) one strain of RHDV1 to achieve localised rabbit control.
Biosecurity Tasmania currently releases a strain of calicivirus called RHDV1-K5, a naturally occurring variant of RHDV1 from Korea. RHDV1-K5 has been released into wild rabbit populations in Tasmania since 2017 to boost the effectiveness of calicivirus biological control. RHDV1-K5 only affects European rabbits and poses no risk to human health or other non-target species.
PestSmart - Boosting Rabbit Control - visit this website for more details on the national release of RHDV1-K5.
An outbreak of a second form of calicivirus, known as RHDV2, was first detected in Australia in 2015 and Tasmania in 2016. It is unknown how RHDV2 entered Australia or Tasmania. RHDV2 is not currently used as a biological control agent for wild rabbits in Australia.
For further information on RHDV2 visit the NRE Tas webpage: RHDV2 - What is it and how to protect your domestic rabbit
RHDV1 and RHDV1-K5 are different strains of the same calicivirus.
Despite the name similarities, and the similar modes of death, RHDV1 and RHDV2 are different types of caliciviruses.
How is RHDV1-K5 Delivered?
In Tasmania, the RHDV1-K5 virus is introduced using baited carrots. Use of the RHDV1-K5 virus is restricted to trained Biosecurity Tasmania staff and other people who are assessed as competent.
RHDV1 is widespread in rabbit populations in Tasmania. The release of the virus may not be the best control option in all situations; it is only considered for use in areas where:
- other control techniques are not suitable; and,
- there has been no evidence of RHDV1 for over 12 months.
How does RHDV1 affect rabbits?
A rabbit infected with RHDV1 will develop the disease within one to three days. Greater than 75 per cent of infected rabbits will die from the disease. Infected rabbits end up with ‘cold-like’ symptoms, become lethargic and then die quickly from multiple organ failure.
It should be noted that some rabbits die very quickly from the disease and can look relatively normal externally. They may also show very few visible changes to the internal organs.
Generally, only rabbits older than 12 weeks are susceptible to the RHDV1 and RHDV1-K5. Rabbits younger than 12 weeks that are infected are less likely to die than older rabbits. Young rabbits that survive infection become immune adults.
Vaccine for domestic rabbits against RHDV1
The vaccine that is used to protect rabbits from RHDV1 (Cylap®) also works with RHDV1-K5 and can be provided by your local vet. Validation trials by the NSW Department of Primary Industries demonstrated that all rabbits vaccinated with the current vaccine survived infection with RHDV-K5 whilst none of the unvaccinated rabbits survived.
The RHDV1 vaccine is safe to use on pet and farmed rabbits. As with any vaccine for animals or humans, only vaccinate your rabbit when it is healthy.
Your veterinarian can advise on other issues to be aware of when having your rabbit vaccinated.
Protecting your pet and farmed rabbits from RHDV
Effects on other species
There is no scientific evidence that RHDV1 infects any other animals.
Australia has tested for the virus in at least 33 representative animal species, domesticated and wild, native and feral. All were given large doses of the virus and no signs of infection were observed. Worldwide, 43 different species have been tested and the virus did not infect any of them.
No evidence of RHDV1 infection has ever been reported for humans. International laboratories confirm that human infection with RHDV is not known to occur and no health effects have been seen, even in people working very closely with the virus.
In addition to rabbits, RHDV2 has been detected in hares in Europe.