Cases of Legionnaire’s disease have been on the rise in Quebec since 2006, according to the latest Flash Vigie bulletin from the Ministry of Health, which explains the situation, particularly through the aging of the population.
While the incidence of legionnaires’ disease was relatively stable until 2005 (gross incidence rate ranging between 1.5 and 4.6 per 1,000,000 inhabitants), it began an upward trend in 2006, which is still observable. in 2017, notes the Ministry of Health.
Excluding 2012, the year in which Quebec experienced the largest outbreak in its history, with 183 people affected and 13 deaths in the capital, the annual gross incidence rate dropped from 4.7 to 21.6 1,000,000 inhabitants between 2006 and 2017.
According to the Ministry of Health, this increase can be attributed to several factors, including improved detection and reporting of cases, increased vulnerability of the population to the disease (aging population and increased use of immunosuppressive therapy, for example) and greater use of potential sources of legionellosis (air conditioners, fountains, domestic spas, complex piping systems favoring the colonization of bacteria, etc.).
Last summer, 10 cases of legionnaires’ disease associated with a potential exposure in the city of Granby were the subject of an investigation by the Regional Public Health Department of Estrie. The numerous environmental levies carried out did not make it possible to identify a common source at risk, reports the ministry. According to him, hypotheses remain an intermittent environmental source in Granby or more than one source of exposure in Granby or elsewhere.
Also in 2017, the Public Health Department of Mauricie and Center-du-Québec detected an outbreak of 10 cases of Legionnaires’ disease. The investigation identified a water cooling tower located in downtown Trois-Rivières.
The source most often involved
Water cooling towers appear to be the most common source of contamination during major outbreaks (as in Quebec City in 2012). New provisions relating to the maintenance of towers adopted in 2014 now require the owners to send the Régie du bâtiment du Québec precise information concerning their installation and to set up a maintenance program.
Except there are other sources of exposure to Legionnaires’ disease, especially in the home, the ministry said. To prevent the risk of infection, it is particularly recommended to maintain the temperature of the water heater to 60 ° C, to limit the duration of the showers so as not to exhaust the supply of hot water in the water heater and well clean appliances that emit suspended water droplets (showerhead, whirlpool, humidifier, etc.)