More about RHDV1 K5
European rabbits are significant agricultural and ecological pests in New Zealand. They compete very effectively with livestock for pasture, and 7 to 10 rabbits may consume as much feed as one ewe. Rabbits also provide a stable food source for ferrets, which are carriers of bovine tuberculosis. Burrowing and scrapes cause extensive damage on erosion-prone soils, so much so that agricultural land can be rendered useless and water quality declines. Historically, rabbit-infested farms were abandoned because owners could not make a living.
Rabbits also threaten native biodiversity and conservation values by over-browsing vulnerable plant communities, and, as year-round prey, support increased numbers of mammalian pests (stoats, cats, ferrets) that predate on native birds and animals.
Following extensive research, a new variant of rabbit haemorrhagic virus known as RHDV1 K5 has been approved for registration in Australia by the Australian Pesticides and Veterinary Medicines Authority (APMVA). The Australian release of RHDV1 K5 is currently underway.
RHDV1 K5 is also a potentially significant biological control tool for pest rabbits in New Zealand. While exact figures are unknown, it is expected there will be improved knockdown in those areas where the current strain of RHDV is less effective. This could be anywhere from 0 to 40% and will depend on the location of the rabbit population and the number of susceptible animals within the population.
RHDV1 K5 release project
Environment Canterbury is part of a national consortium of pest management agencies leading a programme to import and release RHDV1 K5 into New Zealand. The consortium, that includes regional councils, Federated Farmers, the Department of Conservation and Land Information New Zealand, is targeting the release of the new strain in March 2018.
RHDV1 K5 is expected to boost the effects of the existing RHDV1 strain and help slow the increase in wild rabbit numbers. While exact figures are unknown, it was expected that there would be improved knockdown in areas where the current strain is less effective. Research shows that autumn is the optimal time to release the virus as immune young rabbit numbers are low and the vectors, such as flies, are active.
Support will be required from landowners, farmers and other stakeholders that are likely to benefit from the release. The highest likelihood for success will be through the combined collaborative efforts of the national consortium, regional councils and landowners working closely together. A controlled release will also ensure that a high quality commercially prepared product can be made available to landowners to improve effectiveness.
Latest update: February 2018: Approval gained to release new rabbit calicivirus strain
The Ministry for Primary Industries (MPI) has approved applications for the importation and release of the new Rabbit Haemorrhagic Virus Disease strain known as RHDV1 K5. This decision is a significant milestone for the national consortium of agencies seeking to release RHDV1 K5 to reduce the significant environmental and agricultural impacts of wild rabbits.
The major nationwide release will be undertaken through March and April 2018, as research suggests this is the optimal time to increase the effectiveness of the virus against wild rabbit populations. The controlled release will use a high-quality commercially prepared product at selected sites identified by participating local councils.
Whilst not the ‘silver bullet’ for rabbit control, it is anticipated that the new strain will greatly assist the control of wild rabbit populations by supplementing more traditional control methods. The impact of the RHDV1 K5 release will be monitored at a range of representative sites.
RHDV1 K5 is not a new virus. It is a Korean strain of the existing RHDV1 virus already widespread in New Zealand and only affects the European rabbit. RHDV1 K5 was selected for release because it can better overcome the protective effects of the benign calicivirus (RCA-A1), which occurs naturally in wild rabbit populations in New Zealand.
A vaccine (Cylap) is available in New Zealand which has been helping to protect rabbits from the current RHDV1 for many years. Studies undertaken by the Australian government indicate this vaccine will help to protect pet rabbits against the RHDV1 K5 strain. Pet rabbit owners are advised to talk to their local veterinarian to ensure their rabbits have the best protection available. Zoetis, the manufacturer of the vaccine has confirmed that additional vaccine supplies have been made available in New Zealand for the release.