David Butler-Jones, Canada's chief public health officer, says Canadians shouldn't panic about swine flu. (CBC)

Canadians shouldn't panic about swine flu if the World Health Organization raises its pandemic alert level to the highest level, the country's chief public health officer said Monday

"It’s important to note that should a pandemic alert be raised, this does not mean the virus is more severe or dangerous," said David Butler-Jones during a news briefing in Ottawa.

Earlier Monday, WHO spokesperson Dick Thompson said the organization could raise its pandemic alert level to six — the highest on its risk chart — as more cases of swine flu are reported around the globe.

In an interview with the Spanish newspaper El Pais published Monday, WHO chief Margaret Chan also implied the alert level could be raised.

Butler-Jones said WHO's alert levels are simply a global representation of the outbreak.

The current level, Phase 5, means the virus has spread in more than two countries in the WHO region, he said.

"Phase 6 would simply mean that we are seeing the virus spread locally in countries in additional WHO regions," he said.

Canada is "well positioned" to deal with any future escalation in the alert level, he said.

By Monday afternoon, Canada had 140 cases of the H1N1 flu virus, including 41 new cases in British Columbia, Alberta, Ontario, New Brunswick, Nova Scotia and Prince Edward Island.

Butler-Jones said an Edmonton girl is the country's first severe case of swine flu. The girl, whose age was not given, is in hospital.

Butler-Jones said health officials don't know why she became so ill while most Canadian cases have been mild.

"The news of this first, more severe case, although disconcerting, is not surprising and it does not change the course of action that we are taking," he said.

The case underscores a few things about the disease, he said, including that it does not respect borders or age.

"It is a very, very serious disease that takes its toll on people, young or old. So we need to stay vigilant," said Butler-Jones, who stressed Canadians must wash their hands, cough or sneeze into their sleeves and stay home from work or group gatherings if feeling ill.