Dr. Gerry Predy, senior medical officer of health for Alberta Health Services (left), and Dr. Andre Corriveau, Alberta's chief medical officer of health, address the media Monday in Edmonton. (CBC)

Alberta has six new cases of swine flu, including one that federal officials are calling Canada's first severe case of the illness.

The severe case involves a young girl who was first admitted to hospital in Edmonton on Thursday.

"Canada is reporting its first severe case of the H1N1 flu virus," Canada's chief public health officer, Dr. David Butler-Jones, said at a news conference Monday afternoon. "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."

The girl, whose age was not given, was described as being in "stable condition under care." The girl did not travel to Mexico and health officials are still trying to determine where she might have picked up the illness.

"We are following up on all the contacts and ensuring that we track down anybody else who might have picked up the infection," said Dr. Gerry Predy, the senior medical officer of health for Alberta Health Services.

Predy would not say if the girl's condition was life-threatening nor would he confirm if the girl was of school age, citing a desire to preserve patient confidentiality. No schools will be closed, he said.

While federal officials referred to it as a "severe" case, Alberta public health officials downplayed the extent of the girl's illness at a media briefing in Edmonton earlier in the day.

"We had one young girl that was admitted to one of our hospitals with a more severe form of illness that is currently under care and is doing well," said Dr. Andre Corriveau, Alberta's chief medical officer of health.

In an email to CBC News on Monday afternoon, Alberta Health spokesman Howard May said it was "very premature" to refer to it as a severe case, pointing out that swine flu "may or may not be a contributing factor" to the girl's hospitalization, and that it's too early to say if any underlying medical conditions or other symptoms also played a role.

The other five cases involve adults who had mild symptoms and are recovering at home.

Of the new cases, three are in central Alberta, two are in Calgary and one is in Edmonton. Three are male and three are female. Monday's announcement brings the number of swine flu cases in Alberta to 24.