Quebec's public health board said it is seeing fewer cases of infections caused by legionnaires' disease.

At a news conference on Friday, director of public health for the Quebec City region François Desbiens announced seven new cases of the disease. This brings the overall toll to 158 infections, including nine deaths since July.

Authorities say the number of patients being admitted with the infection seem to be tapering off.

Quebec City Mayor Régis Labeaume wants the public health board to release the locations of buildings that were infected with legionnaires' disease.

According to the public health department, many building owners have not responded to the government's request to inspect their cooling towers.

Labeaume has also asked Desbiens to maintain a high level of honesty while investigating the matter.

Quebec's Public Security Minister Robert Dutil demanded a coroner's inquest into the matter.

Deadly bacteria

The source of the outbreak is believed to be the cooling systems atop two buildings in Old Quebec. Local authorities have disinfected the cooling systems in more than 100 buildings.

Inspectors are currently revisiting about 30 of them for reinspections and to make sure building owners have complied with cleanup directives.

Deadly legionella bacteria can grow in the stagnant water of systems called cooling towers, and then spread in droplets through ventilation.

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. Most people are not at risk.

The disease can be treated with antibiotics if it is diagnosed in time. There has never been a documented case of drug-resistant legionella.