A new study has revealed French Polynesia is a potential gateway for viruses like Zika entering other parts of the world.
The territory experienced a Zika epidemic between October 2013 and March 2014.
The report in France's Weekly Epidemiological Bulletin said the reasons for the epidemic were not known but favourable conditions existed, including a lack of immunity to the virus and the presence of at least two species of mosquitoes which could be carriers.
The researchers said the Zika strain which has been circulating in South America since 2015 was very close genetically to the one found in French Polynesia, suggesting it was introduced to Brazil from the Pacific.
They concluded the territory was therefore a potential point of entry for the disease to other places especially Europe and metropolitan France where the mosquito type (Aedes albopictus) was established.
Zika was estimated to have attacked two thirds of the French Polynesian population but the researchers said models indicated that figure could be as much as 94%.
From the beginning of November 2013 to early March 2014, 69 neurological complications or cases of auto-immune disease possibly linked to Zika were identified, including 42 cases of Guillain-Barré Syndrome.
French Polynesia usually records less than five cases of the syndrome a year.
Some cases of babies born with abnormally small heads - microcephaly - were also recorded.
Head of Surveillance at French Polynesia's Health Ministry, Henri-Pierre Mallet, said some babies were born during that period with severe brain abnormalities, without microcephaly.
He said a study was underway looking at the effects on babies born to mothers who were infected.