At least two Albertans have contracted the Zika virus over the last three years, which is being linked to severe birth defects in Brazil, health officials said Thursday.

The most recent case was a woman who returned from Colombia in December. The other was from 2013 in a person traveling in southeast Asia.

Both people picked up Zika while travelling in areas affected by the virus, which is spread by mosquitoes. But Alberta Health Services won't say where they live in the province.

On Thursday, Dr. Margaret Chan, director general of the World Health Organization, called the spread of the virus "explosive."

But there's little need for concern in Alberta, according to Dr. Martin Lavoie, acting chief medical officer of health for the province.

Pregnant women most at risk 

"Right now there's no risk of acquiring Zika virus in Canada because we don't have the mosquitoes that can carry the virus," Lavoie said.

He says it can't be spread person to person by casual contact and as long as you're not pregnant, you shouldn't be too affected by it.

"Zika is actually a mild infection and usually, actually, for most cases, 80 per cent, eight out of 10 approximately, will have absolutely no symptom that they can identify," Lavoie said.

"In the last 20 per cent, one in five will have some very mild symptoms, so maybe a bit of fever, red eyes, a rash, red patches on the body and some joint pain here and there."

He said it usually goes away within a few days. But Lavoie is urging pregnant women, or those planning on getting pregnant, to avoid travel to areas where the virus is present.

"Obviously that is the best protection. Don't expose yourself during pregnancy."

For people traveling in Zika-affected areas,Lavoie suggests limiting skin exposure and using mosquito repellent containing DEET.

The World Health Organization will be holding an emergency meeting of independent experts Monday to decide if the virus outbreak should be declared an international health emergency.

Canadian Blood Services will soon stop accepting blood donations from people returning from countries hit by Zika.