Canadian health officials say eight people have died in a rare outbreak of Legionnaires' disease in the province of Quebec, having identified more than 100 cases of the dangerous strain of pneumonia since July.

Aiming to stop the outbreak, public health workers have inspected and disinfected about 89 cooling towers in Quebec City, the provincial government said in a release on Sunday. All told, 104 cases have been identified so far.

Legionnaires' disease is caused by bacteria that can grow in cooling towers, showers and other water sources. It mostly affects people already in poor health, spreading as they inhale small droplets of contaminated water suspended in the air.

The illness, named for a 1976 outbreak at an American Legion convention in Philadelphia, is rare in Canada, with only about 75 cases reported each year, according to a fact sheet from the federal public health agency.