While a sexually transmitted case of Zika virus in New Zealand would be a concern, it's relatively rare, health experts say.
The Ministry of Health yesterday said it appeared a man who contracted the virus had passed it on to his female partner who had never travelled to a Zika-affected country.
The ministry said the virus had either been sexually transmitted or a mosquito had come in the man's luggage, which had then infected his partner.
University of Auckland senior lecturer Dr Siouxsie Wiles said it was unlikely a mosquito with the virus had reached the country.
There were a handful of cases documenting possible sexual transmission of the virus from men to women, she said.
"Sexual transmission of the virus is not the main route of infection. It is still quite rare."
University of Otago lecturer Professor Michael Baker said if the case was confirmed it would be quite significant.
"There are many unanswered questions about sexual transmission of Zika, including the level of risk, whether asymptomatic cases can transmit the virus, and the period during which transmission can occur."
However, Prof Baker said it was important to remember the main way the virus was transmitted was through mosquito bites in Zika-infected areas.
An investigation into the New Zealand case is ongoing, but both infected people have now fully recovered.
The WHO in January said the virus was "spreading explosively" and could infect as many as four million people in the Americas alone.
Thousands of children in Brazil have been born with suspected cases of microcephaly, in which infants are born with smaller-than-usual brains, which is linked to the Zika virus.
In 2014 there were 57 Zika virus notifications in New Zealand and six in 2015.
As of last Thursday, there had been 12 confirmed cases and two possible ones in 2016, with 11 of those people having been infected in Tonga.