New disease strain unleashed against rabbits

A wild rabbit snacking on its favourite food - pasture meant for stock. Photo/George Novak

A new strain of the rabbit-killing calicivirus disease will be introduced into selected Bay of Plenty locations next month.

Regional council biosecurity manager Greg Corbett said four releases were planned for the Bay and the council was working with property owners.

''Like the last release, it will most likely spread across the whole rabbit population over the next year or so," Corbett said.

He said rabbit numbers were reasonably high in areas of the Bay, with Pongakawa Valley probably the most rabbit-prone. The timing of the release was being co-ordinated with the Waikato Regional Council.

The decision to release the Korean strain of Rabbit Haemorrhagic Virus Disease (RHDV) followed Environment Canterbury receiving approval from the Ministry for Primary Industries to import and release the virus that was mainly spread by flies and fleas.

The release of the virus would not affect pet rabbits provided owners continued their vaccination programmes.

The Ministry said New Zealand's existing Cylap vaccine had proved effective in Australia after the Korean strain was introduced in March 2017. There had been no rabbit deaths since the introduction of the new strain.

''However, like all vaccines, Cylap will not provide protection in all cases. Pet owners should continue to vaccinate rabbits and seek advice from their local vet on additional measures to minimise the risk of RHDV infection.''

Federated Farmers Bay of Plenty provincial president Darryl Jensen said the release would get rabbits down to manageable levels in problem areas.

He said Pongakawa was a hot spot because rabbits preferred free-draining sandy soils.

''Rabbits don't like moisture and damp. They like a nice dry environment.''

There were certain hillsides where rabbit numbers had increased so much you could see them going every which way, he said.

Farmers and tried shooting and poisoning but it had not kept on top of the problem. The increase in the rabbit population had led farmers to surmise that rabbits were becoming resistant to the previous strain of the haemorrhagic virus, he said.

Jensen said the big advantage of RHDV was that it was rabbit specific and did not cross over to other species.

The Bay's other hot spots included areas around the Rotorua Lakes where forests and native bush bordered pasture. Rabbits burrowed in the forest margins because it was a safe haven, coming out into the open to feed. Another hot spot was the coastal strip just past Opotiki, he said.

An information sheet released by the Ministry said RHDV caused hepatitis and rabbits died from the rapid onset of multiple organ failure. Death occurred faster with the new strain, with rabbits dying within two to four days of contracting the virus.

The new strain was selected because it better overcomes the protective effects of the benign calicivirus which occurred naturally in New Zealand's wild rabbits.

Protecting pet rabbits from haemorrhagic virus disease
- Vaccinate from 10 weeks of age plus annual boosters.
- Control insects, especially flies and fleas, as much as possible.
- Remove uneaten food every day.
- Rabbit-proof your backyard to prevent access by wild rabbits.
- Regular disinfection of equipment and materials such as hutches and bowls.
- Limit contact with unfamiliar pet rabbits.
- Avoid cutting grass and feeding it pet rabbits if there is the risk of contamination from wild rabbits.
Source: Tauranga Holistic Vets