In May 2015, a rabbit in Canberra was found to be infected with a new strain of rabbit haemorrhagic disease virus (Calicivirus), known as RHDV2. This new virus strain was first reported in France in 2010 and has been found in several other European countries. It is not known how it entered Australia.
This new virus strain is distinct from RHDV1, the strain released in Australia in 1996 for the control of wild rabbits. Since the effectiveness of the RHDV1 strain as a biocontrol agent has decreased with time, a new naturally occurring variant of RHDV1 (called K5) is proposed for release, pending approvals. This intends to boost the effectiveness of the current RHDV1 strain.
In June 2016 RHDV2 was also detected in European brown hares (Lepus europaeus), a species not previously known to be infected with the virus. The virus has not been found to infect or kill any native or other introduced species. Both the European brown hare and the European rabbit are invasive species and considered a threat to Australia’s environment and agricultural industry.
Protection against RHDV2
The calicivirus vaccine currently used in Australia (for RHDV1) may only provide partial protection against the RHDV2 strain. However, if a more rigorous vaccination programme is used, this may assist in protecting against RHDV2.
Protection against RHDV1 (K5)
A NSW Department of Primary Industries pilot study (through the Invasive Animals CRC) assessed the current calicivirus vaccine for its effectiveness in protecting domestic and production rabbits from K5. Results of this study indicated that the currently registered vaccine is effective against K5 if correct vaccination protocols are followed.
Recommendations for vaccinating rabbits against all strains of calicivirus are available on the Australian Veterinary Association website.