Zika case confirmed in Ontario, may be sexually transmitted

The first positive case of Zika virus thought to be transmitted sexually within Canada occurred in Ontario, provincial and federal health officials say.

Health officials suspect patient contracted virus from partner who travelled to Zika zone

The Zika virus is primarily spread by the bite of an infected Aedes species mosquito, the U.S. Centers for Disease Control says. (US Centers for Disease Control)

The first positive case of Zika virus thought to be transmitted sexually within Canada occurred in Ontario, provincial and federal health officials say.

Testing at the Public Health Agency of Canada's national laboratory in Winnipeg confirmed the infection. 

"The individual from Ontario is suspected to have contracted the virus from a sexual partner who was diagnosed with Zika virus after travelling to an affected country," PHAC and the Ontario Ministry of Health and Long-Term Care said in a joint statement Monday. 

A spokesman for Ontario's health ministry said they are not able to provide details on the specific patient's case because of privacy requirements. 

Bites from infected mosquitoes are the main way the Zika virus spreads. Sexual transmission is also suspected, health authorities say, and has been reported in other countries. It's not yet known how commonly Zika virus is sexually transmitted.

Canada has no confirmed cases of locally acquired Zika virus through mosquitoes, and the overall risk in this country remains low.

Pregnant women and those planning a pregnancy should avoid travel to countries with ongoing Zika virus outbreaks, health officials advise.

If travel cannot be avoided or postponed, strict mosquito bite prevention measures should be taken given the association between Zika virus infection and increased risk of serious health effects on a fetus.

Advice to travellers returning from countries with ongoing outbreaks of Zika virus includes:

  • Any woman planning a pregnancy should wait at least two months before trying to conceive to ensure that any possible Zika virus infection has cleared the body.

For male travellers, it's recommended:

  • Those with a pregnant partner should use condoms for the duration of the pregnancy because Zika virus can persist for an extended period of time in the semen of infected males.
  • Wait six months before trying to conceive, and use a condom.
  • Consider using condoms with any partner for six months.

In March, health officials in Saskatchewan reported a woman who had not travelled outside the country was suspected of having Zika virus after she had sex with a man diagnosed with Zika after he travelled to an affected area.

"At this point, because the testing takes two to three weeks, and if the testing is non-confirmatory further testing will be required, we are not able to confirm the case under investigation in Saskatchewan. But Ontario has reported their first confirmed case of sexual transmission," Saskatchewan's Chief Medical Health Officer Dr. Saqib Shahab, said Monday. 

To date, there have been 56 other confirmed cases of Zika among Canadians. One is confirmed through sexual transmission and one is under investigation, Shahab said. 

​Last week, health officials in British Columbia said two pregnant women in the province tested positive for Zika virus. The women were among seven positive travel-related cases in B.C. 

The U.S. Centers for Disease Control and Prevention has said Zika virus is confirmed as a cause of the birth defect microcephaly and other serious birth defects. Not all babies will have problems, and research is under way to try to determine what the likelihood could be.

Illness from Zika infection is typically mild and lasts a few days. The majority of those infected do not have symptoms.