WELLINGTON -- Rabbit calicivirus disease has been shown to cause health problems in humans, an American expert told Parliament's primary production select committee.

Professor Alvin Smith, who has studied caliciviruses for 25 years, told the committee by teleconference yesterday there was evidence, but no proof, that RCD had affected humans.

A study in Geelong, Australia, had shown people exposed to RCD had double the number of symptoms -- including diarrhoea, vomiting, flu-like illness, and miscarriages -- as people who were not exposed or only lightly exposed, he said.

Dr Smith said the Australian study would be released this month.

The committee is considering the Biosecurity (Rabbit Calicivirus) Amendment Bill, which aims to retrospectively legalise RCD which was illegally imported last year.

Dr Smith, from Oregon State University, told the committee that creating an RCD epidemic was "playing with dynamite".

"There's no rational basis in science in taking this risk."

Like the chicken flu virus, which had recently infected people in Hong Kong, RCD could also cross to humans, Dr Smith said.

Four of the five types of calicivirus were known to infect humans. Experimental work in Geelong had shown antibodies had developed in 11 of 34 species tested, which indicated it was not just specific to rabbits.
Kitchen blenders

As a virus, RCD would mutate into many different forms, which was how it had survived in nature. No two viruses would have exactly the same genetic sequence.

"All of this is not proof, but it is compelling evidence," he said.

He also criticised the practice of farmers using kitchen blenders to make RCD "home brews" to spread the virus. Blenders caused air-borne infectious particles, which could drift on air currents.

He suggested New Zealand could attempt to eradicate RCD in the North Island, where it was less established.

However, Australian scientist Tony Robinson, who has studied the epidemiology of RCD and is involved with the Australian RCD programme, disagreed with Dr Smith's views.

"I don't believe there's any evidence that this virus infects other species and humans, there's no evidence for that."

RCD was one of the most highly scrutinised viruses yet, he told the committee.

It was not reasonable to compare RCD with chicken flu, as influenza was known to infect humans, he said. To compare the two was scaremongering.