Published Date: 2012-08-25 09:27:15
Subject: PRO/EDR> Legionellosis - Canada (03): (Quebec) fatal, cooling tower susp, RFI
Archive Number: 20120825.1262366
LEGIONELLOSIS - CANADA (03): (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: Thu 23 Aug 2012
Source: castanet.net [edited]
The death toll in Quebec City from Legionnaires' disease has increased to six, with the number of people affected now listed at 65. The latest cases were reported Thursday [23 Aug 2012] by public health authorities.
"We're very worried by the current situation," said Francois Desbiens, director of public health for the Quebec City region. "It's the biggest outbreak of Legionnaires' that Canada has seen in years."
The number of reported deaths has doubled, from three, in a few days. However, officials expressed hope that things might soon improve. They said thorough inspections have been completed in 28 buildings in two different neighbourhoods, near the provincial legislature. The process of checking, and cleaning, the cooling towers in those areas was supposed to have been completed Friday but it ended faster than scheduled.
"We disinfected and cleaned all the towers simultaneously," Desbiens said. "We should be able to see the situation correct itself in five to six or seven days. I'm making that estimate because the incubation period is two to five days. It is very possible that we will have other cases of Legionnaires' disease (Friday), Saturday, Sunday, Monday and Tuesday. These would be people who were contaminated before we managed to disinfect the towers."
The bacteria grows in stagnant water in the cooling units used in large buildings before circulating in the air-conditioning system. It then passes into the air as fine droplets. Inhalation of the droplets is generally not a problem for people in good health but it can affect heavy smokers or those with weakened immune systems. Symptoms include a high fever and breathing problems.
Authorities say there are usually two or three cases of legionnaires' disease every year. They still do not know which building is the origin of the outbreak, although they expect to have a better idea within a month from samples taken in recent days. The municipal government expressed dismay over the cleaning standards in some of the buildings. "We saw it all" during inspections, said Chantale Giguere, assistant director general for public security in Quebec City. She said she wants to see a provincial law that would force building owners to better maintain cooling towers. Mayor Regis Labeaume, who was on holiday, said he was returning early and was expected to meet with reporters Friday morning.
ProMED-mail from HealthMap alerts
[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 (02): (Quebec) fatal, cooling tower susp. 20120805.1228680), there were a total of 40 cases, including 3 fatalities, of Legionnaires' disease. Now there are a total of 65 cases, including 6 fatalities. We are again not told of the species of _Legionella_ involved in the outbreak nor 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.
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