New Zealand mosquitoes may be able to transmit the Zika virus, researchers have found.
Scientists in Brazil have shown Culex quinquefasciatus -- one of 15 mosquito species found in New Zealand -- is able to be infected with the virus in the lab.
They were conducting more research to learn whether the species was transmitting Zika in the wild.
Dr Jose Derraik of the University of Auckland's Liggins Institute said the findings showed it was "potentially dangerous" to assume New Zealand did not have mosquitoes capable of transmitting the virus.
He is warning people arriving from countries with Zika outbreaks to avoid being bitten my mosquitoes in New Zealand, to minimise the chance of local transmission.
His comments come after health authorities this week revealed they are investigating a possible sexually transmitted case of the Zika virus in New Zealand.
Dr Derraik said it was true that the mosquitoes said to have been transmitting the virus overseas -- mainly Aedes aegypti and Aedes albopictus -- do not occur here.
However, the species being studied by Brazilian researchers, Culex quinquefasciatus, is established in much of the North Island and in northern areas of the South Island.
"So, while it is correct to say that the known mosquito vectors of Zika virus are not present in New Zealand, it is misguided [and potentially dangerous] to assume that we do not have mosquito vectors capable of transmitting the virus.
"Zika virus in particular has been very poorly studied until the outbreak in Brazil, which means that we simply do not know whether the species of mosquitoes in New Zealand are able to transmit the virus to humans."
Dr Derraik said Culex quinquefasciatus was the first foreign mosquito to become established in this country, having been here since at least 1848. It was considered to be a species of "domestic" habits, with a tendency to live in association with humans.
"It breeds in a variety of man-made habitats, including polluted waters in drains and septic tanks. Culex quinquefasciatus is considered a pest in some urban areas, and it will often come indoors to bite humans in the night time.
"As a result, even though the risk of mosquitoes transmitting viruses to humans in New Zealand is lower than in other countries, this possibility cannot be simply disregarded."
On Thursday, the Ministry of Health revealed a New Zealand man became ill after visiting a country where the Zika virus was actively transmitted.
Ministry spokesman Dr Don Mackie said the man tested positive for the Zika virus and his female partner, who has not recently travelled to a Zika-affected country, has also tested positive for Zika.
Both have now fully recovered and suffered only mild symptoms.
Dr Mackie said two potential modes of transmission were being considered -- whether the virus was transmitted through unprotected sex, or the woman may have been bitten by an infected mosquito brought into the country in her partner's luggage.
He said there was limited scientific evidence to suggest the virus could be be sexually transmitted.
Surveillance of the property was being carried out to check for any exotic mosquitoes. None have been detected.
Dr Mackie said the risk to the wider public was extremely low. "The species of mosquito that can spread Zika are not native to New Zealand."