Saskatchewan may have Canada's first case of the Zika virus transmitted sexually.

Dr. Denise Werker, the province's deputy medical health officer,  said Thursday that there were already two confirmed cases of the Zika virus in travellers who returned to Saskatchewan from countries that have the virus.

Now, a woman who did not travel outside of the country is also suspected of having the virus.

Werker said the woman had sex with a man who was diagnosed with the Zika virus after travelling to an affected area.

Werker wouldn't say if the woman is pregnant.

Zika mosquito Brazil

The Zika virus is usually transmitted through a specific type of mosquito. Sexual transmission is also possible. (Felipe Dana/Associated Press)

An official from the Public Health Agency of Canada said Thursday it was awaiting laboratory confirmation on the case, which was the only known example in the country linked to sexual transmission.

Werker said there have only been 10 cases elsewhere in the world where transmission of the Zika virus was through sexual contact: six in the U.S. and cases in Argentina, Italy, France and New Zealand.

Men who have been to areas affected by the Zika virus should use a condom during sexual intercourse, she said.

"Men could infect women on their return," she said. "Men should use condoms for six months after return from travel."

She noted that 80 per cent of people who have the Zika virus do not show any symptoms and the virus can live for as long as two months in semen.

In the current case under investigation, Werker said, the man was aware that he had the virus.

"He knew that he had Zika and unfortunately there was sexual contact," she said.

Werker added that women who are pregnant or plan to become pregnant are advised not to travel to areas where the Zika virus is present.

Zika virus is associated with a rare condition called microcephaly, in which the baby's head is smaller than normal and the brain may not develop properly.

The federal government's health agency said the precautions relating to condom use are because of the risks associated with birth defects.

"The Public Health Agency of Canada has placed emphasis on its recommendations for condom use for men returning from Zika-affected countries with partners who could become pregnant due to the possible association between Zika virus and increased risk of serious health effects on unborn babies," the agency said.