The World Health Organisation (WHO) has declared the Zika outbreak an international public health emergency.
"Members of the committee agree that the situation meets the conditions for a public health emergency of international concern," said Dr Margaret Chan from the WHO.
The mosquito-borne virus is spreading rapidly and has strong links to a serious birth defect, microcephaly, which causes babies to be born with abnormally small heads and brain damage.
More than 4000 suspected cases have been reported in Brazil, and the new state of emergency means fast-tracked research.
"All agree on the urgent need to coordinate international efforts to investigate and understand this relationship better," Dr Chan said.
The WHO is calling on countries around the world to help bring the problem under control - but Health Minister Dr Jonathan Coleman says New Zealanders have no cause for concern.
"This is only transmitted by a species of mosquito which doesn't exist in New Zealand so there's nothing for people to worry about in New Zealand," he said.
Experts agree the risk is very low, but can't rule it out completely.
"We simply don't know whether the mosquito species that are present in New Zealand are capable of transmitting the virus to humans. Absence of evidence is not evidence of absence," Dr Jose Derraik said.
There have been 10 cases reported in New Zealand so far this year, and each of them have been infected overseas.
"We have great border surveillance procedures as well as information at the border which means that people within New Zealand are safe," Mr Coleman said.
The risk is to travellers, particularly those who are pregnant, heading to affected countries such as the Americas, Samoa and now Tonga.
Despite aggressive tactics to stop the spread of the mosquitoes, travellers are advised to take extra precautions.