Canada’s Chief Public Health Officer has released guidelines suggesting all pregnant women who have travelled to countries affected by the Zika virus be tested due to the possible link to birth defects.

Dr. Gregory Taylor made the announcement Tuesday.

“Women, and in particular pregnant women, we are quite aware are quite anxious about what should happen if they come back from these areas and have potentially been exposed to the virus,” he told CTV News. “We wanted to ensure doctors have some guidance.”

He pointed out that although 75 to 80 per cent of those who get the virus have no symptoms at all, their fetuses may still be affected.

“If a woman has been in one of those countries and has no symptoms and didn’t get sick, there’s still a chance she could have been infected,” said Taylor.

In Brazil, public health officials have linked the virus to microcephaly, a condition where babies are born with unusually small heads. This connection has not yet been confirmed by researchers.

The symptoms of Zika include fever, rash, eye pain, muscle pain and red eyes.

The testing available in Canadians takes about three to four weeks to process. However, Infectious Diseases expert Dr. Neil Rau said the test is imperfect, so pregnant women may also need ultrasounds to make sure the babies are developing normally.

While Dr. Taylor is recommending all recent travellers who present with the symptoms of Zika be tested, those without symptoms are being asked not to seek testing.

Dr. Rau said that’s because the National Microbiology Lab in Winnipeg that conducts the test is already busy enough.

Zika is spreading from mosquitos to humans in at least 33 countries, while there is evidence of local transmission in six more, according to the World Health Organization.

Among the nations affected are Brazil, Colombia, Mexico, Dominican Republic, Panama and Costa Rica.

The Aedes mosquitos that spread Zika are not native to Canada so there is little risk of it spreading locally. However, there have been documented cases of sexual transmission. Blood transfusions are a possible source of infection.

With a report from CTV News' Medical Correspondent Avis Favaro and producer Elizabeth St. Philip