West Melton sheep tolerate a rabbit making its way through their territory.

The government is about to decide whether to allow a new deadly calicivirus into New Zealand to try and decimate a rapidly increasing wild rabbit population.

The Ministry for Primary Industries (MPI) is mulling over an Environment Canterbury (ECan) request to introduce a powerful new strain of rabbit haemorrhagic disease (RHD) into Canterbury following a reported 40 per cent increase of the wild rabbit population over the last 20 years.

Ecan said rabbits are estimated to cost farmers over $100 million a year in the region by competing with stock for food, causing erosion and degrading water supplies. It expects a decision in February.

Jo McKenzie-McLean A popular recreation spot on the shore of Lake Dunstan is being overtaken by dangerous rabbit holes.

An RHD strain from the Czech Republic was illegally introduced by a group of vigilante farmers in Cromwell in 1997 after the government considered, and then rejected, the application to introduce the bug.

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ECan said the rabbit count in the Mackenzie Country in 1996 was 7 per "night count kilometre" and has increased to 10 in 2017 despite the introduction of the first RHD strain.

stock image This rabbit has kicked the bucket.

The new Korean strain called RHDV1-K5 has been selected by Ecan for its deadliness - it was released at 550 sites in Australia in 2017, with a reported 42 per cent reduction in local populations.

RHD kills rabbits in one or two days. Sometimes there are no symptoms. Other times rabbits squeal incessantly, convulse and spasm, get depressed, become anorexic, struggle to breath, as well as shake or bleed from the nose or anus. Opponents say the virus is cruel and pointless given past viral experiments to control populations had not worked.

ECan plans to buy the virus in vials from the NSW Department of Primary Industries at $250 a pop and have them sent over via courier.

Supplied Rabbit holes at the Cromwell Chafer Beetle Nature Reserve in Central Otago.

There are concerns New Zealand's estimated 130,000 pet rabbits could be at risk from the new strain.

A vaccine called Cylap has protected pet rabbits in the past, but there are questions about what it can do to prevent K5.

Gary Stephenson, member of the Rabbit Council of New Zealand, owns two rabbits - Castle and Becket. Stephenson suffers from multiple sclerosis and the rabbits give him comfort when he is struggling.

CALLUM MCGILLIVRAY/ FAIRFAX NZ Kumeu's Norma Spencer lost 52 pet rabbits in ten days to the calicivirus in 2015.

"People are realising how fun they are, how intelligent they are. They are very, very loving. Rabbits are a great stress reliever," he said.

Stephenson has presented a petition to Parliament with 5000 signatures asking it to delay the introduction of the vaccine until Cylap is proven to protect against the K5 strain.

"We're doing everything we can to protect them and I can't believe from everything I've read that this vaccine will work."

PETER MEECHAM/STUFF A wild rabbit in Mackenzie.

The New South Wales Department of Primary Industries tested Cylap on 30 K5-infected rabbits in 2015 and concluded Cylap could do the job.

Stephenson is concerned that the trials for the effectiveness of Cylap were not adequate. He said the rabbits were only exposed to the virus for 30 days, but organisations like the World Organisation for Animal Health recommend a year before confirming the effectiveness of a vaccine.

"Validation for this work can only be done by field trials. None of this was done."

In March 2017, in response to an Official Information Request, MPI said it did not have any of the information requested about Cylap testing in Australia.

K5 has to make it past two laws to be approved by MPI - the Agricultural Compounds and Veterinary Medicines Act and the Biosecurity Act.

In February 2017 the Environmental Protection Authority gave K5 the green flag because it was not considered a "new organism."

ECan originally planned to release K5 in mid-2017 to be timed with the Australian release, but MPI requested more paperwork. The virus struggles to thrive at hotter temperatures, so autumn or winter is considered the best time for its release.

Prior to the introduction of K5 Australia has introduced two viruses over the past 70 years in a bid to eliminate wild rabbits. Both times a small percentage of the population, which was able to withstand the virus, survived and bred.

Ecan said K5 is not a "silver bullet" for rabbit eradication in New Zealand. It was still looking for a "long-term integrated approach" to controlling pest rabbits.

Public submissions to MPI on the Ecan proposal closed in December.