08/29/2012 04:29 EDT | Updated 10/29/2012 05:12 EDT

Legionnaires' death toll rises to nine in Quebec City

QUEBEC - A ninth person has died of legionnaires' disease in Quebec City.

Health officials said today the nine deaths are included in 141 overall cases of the disease to hit the city since July.

Local authorities have disinfected the cooling systems in more than 100 buildings.

Inspectors are currently revisiting about 30 of them to look at the water and to make sure building owners have complied with clean-up directives.

The deadly bacteria grow in the stagnant water of cooling systems, spreading in little droplets through air conditioning. The source of the current outbreak is believed to be the cooling systems of two building towers.

Heavy smokers and people with weak immune systems are most at risk of catching the disease, which is not contagious.

Symptoms include persistent fever, coughing and difficulty breathing.

It can be treated with antibiotics. There has never been a documented case of drug-resistant legionella.