Health authorities in French Polynesnia estimate up to 30,000 people, or about ten per cent of the population, may have been infected by the zika virus over the past six weeks.
The head of the surveillance office, Dr Henri-Pierre Mallet, says the illness is mild but not well understood compared to the concurrent outbreak of dengue fever and the situation is dramatic for the public health system.
He says the authorities may soon need to appeal to regional health authorities and the French government for further assistance.
Dr Mallet says the virus is spread by the Aedes aegypti mosquito and symptoms of the week-long illness include a rash, fever, joint pain and red eyes.
He says it is not as severe as the similar dengue fever but the local population has no immunity to zika.
"So there is a very fast spreading of the infection. And one place is infected with a lot of cases, after that it is better; but another place, again, is infected. And so like that, from place to place, island to island, yes the cases are still increasing and spreading all over the country."
Dr Mallet says people in French Polynesia are getting sick every day, every time and everywhere, but most only need a few days off work to recover.