MONTREAL - Manitoba health officials were investigating a sudden spike in the number of people requiring intensive care for flu-like illnesses Monday, while Quebec reported its first death related to swine flu.

There were 26 Manitobans on ventilators due to flu as of Monday, and that's in addition to the 30 or so people who are on ventilators on an average day for a wide variety of illnesses. The spike prompted the Winnipeg Regional Health Authority to order 15 additional machines.

"We're seeing a number of severe cases of influenza-like illness," said Dr. Joel Kettner, Manitoba's chief public health officer.

"What we've observed is really more severe than what we would expect to see or have seen with typical seasonal influenza in the past."

While the vast majority of people who have contracted the flu have not required hospitalization, the new swine flu seems to be hitting certain groups hard -- aboriginals and people between 20 and 60, Kettner said.

Manitoba did not confirm any new cases of swine flu Monday. The provincial total remains at 40, none of which has been fatal. But Kettner said he expects most, if not all, of the recent serious cases will test positive for swine flu.

More than half of those on ventilators as of Monday were aboriginal. Native leaders have warned that poor housing conditions make it hard to prevent a contagious disease from spreading. One of the hardest-hit communities is St. Theresa Point -- a fly-in reserve 500 kilometres northeast of Winnipeg where some two-bedroom homes house 10 or more people.

More than a dozen reserve residents have been hospitalized in recent weeks, including a pregnant woman who lost her child.

A flu outbreak in Dauphin, Man., forced about one-third of the 280 students at Mackenzie Middle School to stay home last week. Many students were bedridden for a few days, but most have recovered and were back in class Monday.

"We were encouraging students who felt ill to stay at home, (and) hoped that this thing would maybe run its course," said Jack Sullivan, superintendent of the region's school division.

"We put in extra cleaning staff on Friday and really did a thorough cleaning of the school -- you know, hand rails and sinks and fountains."

Quebec health officials, meanwhile, reported the death of a woman over the age of 65. The unidentified woman from Quebec City is the province's first death from swine flu and Canada's fourth.

Dr. Alain Poirier, Quebec's chief public health officer, said the woman had been in fairly good health before she checked into a Quebec City hospital with breathing problems last week. She was treated for bacterial pneumonia.

"She was apparently in good shape and she turned up with an acute respiratory problem," Poirier said, adding he did not know how she became infected with swine flu. She had not travelled recently to Mexico.

Poirier said it was not yet clear whether the virus caused her death or contributed to it.

Quebec has reported 547 cases of swine flu.

The Public Health Agency of Canada has reported more than 2,446 confirmed swine flu cases across the country since early April.