Published Date: 2012-08-21 17:21:23
Subject: PRO/EDR> Legionellosis - Canada (02): (Quebec) fatal, cooling tower susp, RFI
Archive Number: 20120821.1255310
LEGIONELLOSIS - CANADA (02): (QUEBEC) FATAL, COOLING TOWER SUSPECTED, REQUEST FOR INFORMATION
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 20 Aug 2012
Source: CBC News/Montreal [edited]
Amid of a total of 40 infections, 2 more people are dead in an outbreak of Legionnaires' disease in Quebec City, public health officials said Monday [20 Aug 2012]. That's more than twice the number of cases that had previously been disclosed, and surpasses the last outbreak in the city, in 1995, when 12 people fell ill and one died. Officials didn't name or provide details about the 2 new fatalities, which bring the death toll to 3. The 1st to die was an 88-year-old Quebec City woman.
Dr. Francois Desbiens, the director of public health for the Quebec City region, said authorities have begun inspecting downtown buildings that use a cooling tower as part of their ventilation. Public-health officials had already sent 2700 letters to building owners in the downtown core asking them to clean their cooling systems, but the emergence of new cases -- a dozen since Friday afternoon -- is prompting the inspections.
"We're still seeing cases despite the fact that we've asked building owners to take steps," Desbiens said. "So we've decided to go further and investigate every tower again, and for those that haven't had maintenance, to identify them, to inspect them to take a water sample. And to order a disinfection."
Legionnaires' disease, also known as legion fever, is a flu-like pneumonia that affects people with lung problems or weak immune systems. It is caused by bacteria that thrive in warm temperatures and can breed in the stagnant water of cooling towers, before spreading in the mist released by those systems.
It's not contagious and presents no risk to people in good health. The disease got its name in the 1970s [in 1976] after an outbreak of pneumonia among people attending a convention of the American Legion [in Philadelphia, Pennsylvania].
Earlier this month, Desbiens guessed there were about 200 cooling towers in the area where people became sick that could be the source of the infection, but officials said Monday they've narrowed their area of concern down to 22 cooling towers in a core area that will be inspected by the end of the week, and 19 more in a different area that will be inspected after.
Tests on the water in those towers will take 2 to 3 days to get results confirming an infection [contamination] with _Legionella_ bacteria.
There are normally 2 to 3 isolated cases of Legionnaires' disease a year in the Quebec City region.
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[For a discussion of Legionnaires' disease, see ProMED-mail post Legionellosis - UK (02): (Scotland) 20120605.1156972.
In the previous ProMED-mail post of this outbreak in Quebec City (Legionellosis - Canada: (Quebec) fatal, cooling tower susp. 20120805.1228680), there were a total of 15 cases, including one fatality, of Legionnaires' disease. Now there are a total of 40 cases, including 3 fatalities. We are not told of the species of _Legionella_ involved in the outbreak or if genotyping of the clinical isolates has been done. We are also not told of the timeline over which the cases have occurred or any commonality linking the cases. A description of the microbiology and the epidemiology of the outbreak would be helpful.
Legionnaires' disease attacks more frequently and is more severe in individuals who are elderly, are smokers or alcoholic, have an underlying illness, such as chronic obstructive pulmonary disease (COPD) or have a weakened immune system as a result of, for example, organ transplant or taking immunosuppressive drugs (e.g., corticosteroid therapy) for other reasons. However, it is important to emphasize that relatively healthy individuals can also be at risk of contracting the disease.
Genotyping of patient and environmental isolates has become a helpful tool to establish transmission pathways. The predominance of one genotype of _Legionella_ isolated from patient specimens would suggest transmission from a common source. Because _Legionella_ may be found in environmental samples without linkage to any cases of legionellosis, the actual causative infectious reservoir can be confirmed by matching the genotype of clinical and environmental isolates (see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC86783/ and http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2730281/).
However, clinical isolates are often not available because the diagnosis of Legionnaires' disease is commonly made on the basis of serology or the _Legionella_ urinary antigen test, and not by culture of patient specimens.
A map of the affected area can be accessed at http://healthmap.org/r/2Z0O. - Mod.ML]