He took months mapping, dozens of sampled locations and weeks of laboratory sequencing to determine the probable culprit behind a recent outbreak of legionary disease in London, Ontario. – One that killed four people and infected about 100 another 100.
It is only the last example of why it is so difficult to identify where the disease is spreading.
Last week, the health officials of the Health Unit of Middlesex-London (MLU) said that the probable source of the outbreak was the Cooling towers of a local meat processing plant at the east end of the city. Health officials also determined that the installation was probably linked to another outbreak last year that left two dead people and another 30 patients.
And in the New York Harlem neighborhood this summer, he also took weeks of meticulous search to identify the cause of an outbreak of the legionaries there, now linked to cooling towers of a hospital and a close construction site.
When it comes to tracking the source of an outbreak of the legionaries, experts say there are a number of challenges that are brought on the road, from a potential sampling of fountains to testing the bacteria.
“It has been shown that a source for an outbreak for Legionella is not found in 50 percent of cases,” said Dr. Joanne Kearon, an associate health officer of the MLU.
“It’s not like an outbreak of food … where all these people may have been in one place and have been exposed in the same place. Everyone may have been exposed in different places, [because] Legionella travels in the air. ”
A source has not been detected in past outbreaks in Canada, including recent years in Quebec and NEW BRUNSWICK.
Bacteria cause ‘atypical pneumonia’
Legionella bacteria are naturally found in fresh water, such as lakes and streams, as well as the ground. Typically, the amount of bacteria In the environment it is not enough for people to get sick, according to the centers for disease control and prevention (CDC) based in the US.
The bacterium becomes problematic when it grows in the stagnant water of the systems made by humans, such as cooling towers, water tanks, even swimming pools or hydromassage bathtubs. If contaminated water is sprayed or biting in the air and people breathe, it is when they can get sick.
Some people will get a mild disease, called Pontiac Fever, which generally includes fever and headache symptoms, often disappears on its own.
Legionary disease is a more serious way of respiratory disease that appears as an “atypical pneumonia” and generally affects older people with weakened immune systems, said Dr. Philippe Lagace-Wiens, a medical microbiologist at St. Boniface Hospital in Winnipeg.
“You will find patches generally in both lungs, which is again, unusual,” said Lagace-Wiens, who is also an assistant professor at the University of Manitoba.
The symptoms of the legionaries include difficulty breathing, fever, cough, phlegm and, sometimes, muscle pains and diarrhea, he said. The disease is not transmitted from person to person.
“People with weakened immune systems can have a fairly serious disease and actually end up in the intensive care unit,” he said.
Cooling towers a common guilty
Past shoots have been linked to Hydromassage bathtub, Spas And even decorative sources.
But most of the time, the big shoots are the cooling towersPart of the HVAC systems that are often found in the ceilings of industrial and high buildings, which use fans to cool water and help eliminate the heat of buildings.
If Legionella grows in that water, fans can create aerosols and extend bacteria in the surrounding area.
“Aerosols can actually travel many kilometers,” said Vincent Brown, a technical advisor of the Magnus cooling towers maintenance company.
“Then, if the system is not well maintained, infections can actually be several kilometers from the source, which is one of the reasons why it is difficult to find the source.”
The investigation has shown that these aerosols can travel up to six kilometers away. And the outbreaks occur more frequently during periods of Warm climate.
How to find a ‘needle in a pile of needles’
When it came to the outbreak in London, Ontario, many of the cases were concentrated in an area with dozens of cooling towers. But as the cases were, health officials reduced their search to a three -kilometer radius.
“In London, there are simply so many potential sources. It is [like finding] A needle in a battery pile, “Kearon said.
One of the problems that Kearon found and his team was to know where each cooling tower was so that they are tested.
“We do not have a list of each place that has a cooling tower. Therefore, we have our inspectors, literally walking through the streets, driving, above the buildings with binoculars, trying to identify where the possible cooling towers are,” he said.
The sample of cooling towers is another tedious task, said Kearon, and takes approximately half a day to try a single location.
And when the outbreak of a legionary is declared, the owners of buildings often rush to disinfect their systems, he said.
“They will put a lot of chlorine … to try a chemical disinfection,” said Kearon, adding that this can temporarily mask Legionella.
“But without that step of cleaning and scrubbing physically, physically the walls of the system, a biofilm can grow again.”
A biofilm is when bacteria bind to a surface with a protective coating, which often makes it chemically resistant.
London tomorrowA warmer climate could lead to more legionaries outbreaks
London is dealing with an outbreak of legionaries’ disease, something that is happening more frequently in North America and Europe. Joan Rose, director of the Water Alliance of the Michigan State University, joined London Morning to talk about how the bacteria spread and what can be done to avoid future outbreak situations.
Even when a positive cooling tower sample for Legionella, it may not be the exact bacterial subtype which is getting sick to people.
“The fact that we find Legionella bacteria in an environmental source and someone is sick in the same geographical region … does not mean that those two are linked,” said Lawrence Goodridge, professor of microbiology at the University of Guelph.
“We have to show that the two strains of bacteria are identical or very similar to each other.”
During the investigation in London, for example, multiple cooling towers in nine separate locations gave positive for Legionella live bacteria, said the Mlhu.
What happens in the laboratory?
These positive samples were managed by Ontario public health. The organization’s laboratory staff grew bacteria and observed its genetic composition. Then they verified if those samples coincided with what people get sick.
This whole process can take a few weeks, experts say.
“It is likely that I identify Legionella in many environments, but again, it is about making that party between clinical cases and the environmental sample,” said Shawn Clark, a clinical microbiologist of the public health of Ontario that was testing samples for the outbreak in London, Ont.
In total, the MLU collected 160 samples of 49 different cooling towers.
At the end of August, seven weeks after the recent outbreak was declared for the first time, the MLU confirmed that he had found a game and was working with the meat processing plant identified to properly clean its cooling towers.
The Ontario Ministry of Health did not confirm whether the company would face any consequence for the outbreak. After previous shoots in Canada, those affected have filed demands.
