The Public Health Agency is telling pregnant Canadian women who visited the Miami area in Florida on or after June 15 to take precautions against the Zika virus.
The warning comes after U.S. health officials said mosquitoes have apparently started spreading Zika on the U.S. mainland.
Chief Public Health Officer Dr. Gregory Taylor said Tuesday that because four million Canadians visit Florida annually, an unknown number could be affected by the latest U.S. discovery.
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Taylor said any pregnant women who visited the area on or after June 15 should see their health care providers for testing.
He said women who have been to the region should wait two months before trying to become pregnant.
And because the virus can linger in sperm, men should wait six months before attempting to impregnate a partner.
The agency is also advising pregnant women and those planning a pregnancy to avoid travel to the area in south Florida and other countries with reported mosquito-born Zika virus.
"Officials from the U.S. Centre for Disease Control and Prevention believe the transmissions are limited to the Miami-Dade county of Florida," Taylor said.
Taylor stressed that 80 per cent of those infected have no symptoms, and that the main risk is the potential effect on a fetus during pregnancy. The virus has been linked to birth defects.
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He said that the risk to Canadians in Canada from Zika remains low.
He said there have been no reported cases of people infected by mosquitoes in Canada. "Mosquitoes known to transmit the virus are not established in Canada and are not well suited to our climate."
Tests have been conducted on six different species of Canadian mosquitoes, and the research shows they are unable to transmit the virus, he added.
Canadian health officials are monitoring the situation with their counterparts in the U.S. and with the World Health Organization, he said.
Meanwhile, it is unclear what the Zika developments will mean when the weather eventually turns colder and Canadian snowbirds begin to look southward.
"What's going to happen in the next few months, we just don't know," said Taylor.
"It could continue to expand or it could just burn itself out."