A New Zealander has been admitted to hospital with symptoms linked to the Zika virus, the Ministry of Health says.
The ministry said this afternoon it had received nine Zika notifications this year.
All of the travellers had been in the Pacific Islands and eight of them had recovered.
A 47-year man was in Waikato Hospital with symptoms of Guillain-Barre, "a condition which can cause paralysis but from which most patients make a full recovery". He was in a stable condition.
The condition has previously been linked to the Zika virus.
Zika virus: What you need to know
The virus is "generally regarded as a mild illness", the ministry said, but has previously had "additional complications" in a small number of cases.
In Brazil, the virus has been linked with an increase in reported cases of microcephaly, in which babies are born with unusually small heads.
Of the nine people who presented with Zika symptoms, four had been in Tonga and four had been in Samoa, and other person's travel destinations were not known.
Four of travellers were women. Two were not pregnant and the other two were being tested.
Pregnant woman are now being warned about travel to Tonga after a case of the virus was detected in that country.
The advisory is already in place for Samoa.
The Ministry of Health's chief medical officer Don Mackie said the cases needed to be seen in the context of the large number of travellers to the Pacific region.
There were 57 notifications in 2014 and six notifications last year.
Border officials were providing advice to travellers and checking for mosquitoes, which carry the virus.
The World Health Organisation (WHO) says the Zika virus, which is linked to severe birth defects in thousands of babies in Brazil, is spreading "explosively" and could affect as many as four million people in the Americas.
Director-General Margaret Chan said the spread of the mosquito-borne disease had gone from a mild threat to one of alarming proportions.
Dr Mackie said he welcomed the WHO's statement, which acknowledged the heightened awareness of Zika's potential link to birth defects.
"The WHO's international co-ordination of information and advice is useful to us and to our Pacific partners.
"Emerging diseases do arise from time to time, and their newness often means that their public prominence may be out of proportion to the actual risk they pose."
"However, until more is known, the Ministry of Health continues to recommend that women who are pregnant or plan to become pregnant in the near term consider delaying travel to areas with Zika virus present."