Saskatchewan health officials are investigating a possible case of Zika infection that may have been transmitted through sexual activity, one of the province's top health officials says.

"If confirmed this would be the first case of sexual transmission of Zika in Canada," said Dr. Denise Werker, Saskatchewan's deputy chief medical health officer, on Thursday.

The case involves a woman who had sex with a man who had travelled to a Zika-affected country.

Werker emphasized that it is not yet a confirmed case, and said the national microbiology lab in Winnipeg is conducting tests to confirm the diagnosis.

Werker said she decided to publicly disclose the case because many Canadians are travelling for March break, and should be aware of the risks when visiting countries where Zika virus is prevalent.

"We want to make sure persons who are travelling know about the precautions they should take when travelling but also when they return and there has in fact been revised guidance for people when they return because of increasing knowledge that we have about Zika virus," she said.

Werker added that Zika virus can live much longer in semen than it does in the blood and men are advised to use condoms for six months after travelling to an affected country.

The mosquito-borne virus has been potentially linked, in Brazil, to thousands of cases of newborns with abnormally small heads.

Also on Thursday, Health Canada said 33 travel-related cases of Zika virus have so far been reported in Canada.

According to a statement from the agency, there is a very low probability of the disease being transmitted in Canada, since the climate is not suitable to the two species of mosquito capable of transmitting the virus.

There have still been no confirmed cases of locally acquired Zika virus in Canada -- rather people have acquired it elsewhere, then returned to Canada and brought the virus with them.

However, there is evidence to suggest Zika virus will persist and spread in the Americas and the South Pacific, Health Canada said.

Canadians planning to travel to endemic regions are being warned of the ongoing risk posed by the virus.