UPDATED 8.27AM The New Zealand Olympic Committee says it's taking the Zika threat seriously - but it won't stop New Zealand attending the games.

More than 100 medics and experts have signed a letter to the World Health Organisation, calling for the games to be moved until the disease can be properly controlled.

However, the WHO says there is no public health justification for moving or postponing the Olympics due to the spread of the Zika virus in Brazil.

Olympic Committee chief executive and secretary general Kereyn Smith told Mike Hosking they've made a decision to go and will, unless they get the tough word from the top.

"We'd have to be advised by New Zealand Ministry of Health who work with the WHO and other agencies that it's just not acceptable to go all governments, so that's really what it would take," she said.

"Reality is that it's just one event, and because it's big it's important, significant in the spotlight, it just becomes the focal point for so much debate about all sorts of global issues."

LISTEN: Olympic Committee chief executive and secretary general Kereyn Smith speaks to Mike Hosking

However, President of the American University of Sovereign Nations, Professor Darryl Macer, who is from Christchurch, says the Zika virus is nowhere near under control in Rio - and the Olympics needs to be postponed.

Professor Macer said although Rio has been trying to decrease mosquito-borne illnesses - they're up 600 percent this year.

"They might be able to put it under control if they get more support, but it's really stretching it at the moment."

He said the scary thought about the Olympics in August, is that there's no cure for the Zika disease yet.

"We currently don't have any vaccine, we don't know enough about Zika. If we had another couple of years the situation will be much better for treatment of people."

LISTEN ABOVE: Microbiologist Siouxsie Wiles speaks to Rachel Smalley about Zika

University of Auckland microbiologist Siouxsie Wiles told Rachel Smalley it's a difficult thing because we don't know yet the different kinds of species of mosquitoes that can carry the virus.

"So although it's already present in lots of different countries, we don't know if people who are infected then move back to their home countries, if they have the right kind of mosquitos there to spread it, you know, it could spread much further."

But a virology professor from Nottingham University in the UK says the Olympics won't make much of a dent in Zika's spread.

Jonathan Ball said while the virus can be harmful to certain people like pregnant women, it's not risky for the games to go ahead.

"Without doubt, Zika virus infection can be harmful to certain people, like pregnant women. As long as the mosquitos that it needs for its spread is present, then there is a chance of spread.

"We've not seen that happen so far, we've had huge numbers of people visit the affected countries and leave."