Why is it so difficult to find the source of wrath of legoonars?
In London, Onts, many months of mapping cases, dozens of places were sample to determine the potential criminal behind the recent outbreak of Legonaires disease. – One who killed four people and infected about 100 others.
This is just the latest example why it is difficult to indicate where the disease is spreading.
Last week, health officials with Middlesex-Landon Health Unit (MLhu) said that there was a possible source of outbreak Cooling tower of a local meat-processing plant In the eastern end of the city. Health officials also determined that last year the facility was linked to another outbreak, killing two people and 30 others were ill.
And in the summer of this year, in the Harlem neighborhood of New York, it seemed very carefully to identify the cause of the outbreak of a legonaires, Is connected to now Cold the towers from a hospital and nearby construction site.
When it comes to tracking the source of an outbreak of a legonaires, experts say that there are many challenges on the way – from possible sources of samples to really testing for bacteria.
“It has been shown that a source of outbreak for Legionela has not been found in 50 percent of cases,” Dr. Joan Keron said, Associate Medical Officer of Health of MLHUU.
“This is not like an outbreak of a meal … where all these people can be in the same place and are exposed in one place. They can all be really exposed to different places, (because) legionella travels in the air.”
A source has been set in the previous outbreaks in Canada, which includes in recent years Cubec And new Brunswick,
Bacteria causes ‘etipical pneumonia’
Legionella bacteria are naturally found in freshwater, such as lakes and streams as well as soil. usually, Bacteria According to the US-based Center for Disease Control and Prevention (CDC), people are not sufficient to get sick in the environment to get sick.
Bacteria becomes problematic when it grows in the standing water of man-made systems, such as cooling towers, water tanks, even swimming pools or warm tubs. If contaminated water is sprayed or blur in the air and people breathe it, when they can become ill.
Some people will get a mild disease, called pontiaq fever, which usually involves symptoms of fever and headache, and often go on its own.
Legonaires’s disease is a more serious form of respiratory disease that appears as “atapical pneumonia” and usually affects older people with a weakened immune system, Dr. Philip Lagas-Vins, a medical microbiologist at St. Boniface Hospital in Vinypeg, said.
“You will usually find patch on both lungs, which again, unusual,” Lagas-Wines said, who is also an assistant professor at the University of Manitoba.
He said that the symptoms of legionaires include respiratory, fever, cough, phlegm, and sometimes muscle pain and diarrhea. The disease is not sent from person to another.
“People with a weakened immune system can actually be a very serious disease and actually end in intensive care unit,” he said.
Cooling towers a common criminal
Is connected to previous outbreaks hot tubs, Spa More more Decorative fountains,
But most often, there are large outbreaks Kooling towers resultA portion of the HVAC system is often found on industrial buildings and roofs of hyirise, which use cold water to fans and help remove heat from buildings.
If Legonela grows in that water, fans can then make aerosols and spread bacteria in the surrounding area.
“Aerosols can actually travel several kilometers,” said Vincent Brown, a technical advisor with cooling tower maintenance company Magnus.
“So if the system is not maintained well, the infection can actually be several kilometers from the source, which is a reason that is actually difficult to find the source.”
Research has shown that they can visit aerosol Six kilometers awayAnd more often occurs during the outbreak period Hot weather,
Like finding a needle in a pile of needles
When it came for outbreak in London, Onts, many cases were concentrated in an area with dozens of cooling towers. But based on where the cases were, the health authorities limited their discovery to a three -kilometer radius.
“In London, there are just a lot of potential sources. This (such as finding the needle) has a needle in the needle,” Keron said.
One of the issues that took part in Kairan and his team was knowing where every cooling tower was, so that they could be tested.
“We do not have a list of every place that has a cooling tower. So we have our inspectors – literally – driving on the streets, driving around, above the buildings with binoculars, trying to identify where the potential cooling towers are,” he said.
Taking a sample of cooling towers is another tedious task, said that it takes about half a day to test the same place with it.
And when the outbreak of a legendyers is declared, the building owners will often run to disinfect their system, he said.
“They will put a lot of chlorine … to attempt a chemical disinfection,” Keron said, adding it may temporarily lead to the mask of the appearance of Legionela.
“But manually, a biofilm can grow back, without that step of physically cleaning and scrubbing the system walls.”
A biofilm occurs when bacteria connect to a surface with a protective coating, which often makes it chemically resistant.
London morningA hot climate may give rise to outbreaks of more legionaires
London is working with an outbreak of a lehenogenic disease, something that is happening more frequently in North America and Europe. Joan Rose, director of Water Alliance at Michigan State University, joined the London Morning, to talk about how the bacteria spread and what could be done to prevent future outbreak conditions.
Even when a cooling tower sample conducts positive tests for lesella, it may not be an accurate bacterial subtype that is making people sick.
“Because we find Legionela bacteria in an environmental source and someone is ill in the same geographical area … that does not mean that they are both connected,” said Lawrence Gudrij, a microbiology professor at the Gelph University.
“We have to show that two strains of bacteria are similar or similar to each other.”
For example, during investigation in London, several cooling towers at nine separate places conducted a positive test for live legionela bacteria, MLhu said.
What happens in the lab?
These positive samples were controlled by public health ontario. The lab staff of the organization increased the bacteria and saw its genetic makeup. He then checked to see if the people who are getting sick.
Experts say that the entire process may take a few weeks.
“You will probably identify Legyonella in many environments, but again, all of this is about making that match between clinical matters and environmental samples,” said Sean Clarke said, “you probably clinical microbiologist Sean Clarke said.
Overall, Mlhu collected 160 samples from 49 separate cooling towers.
In late August-Seven weeks after the outbreak, MLHU confirmed that he had a match and was working with the meat-transmission plant that was identified to properly clean its cooling towers.
Ontario’s Health Ministry did not confirm whether the company would face any result for outbreak. After the previous outbreaks in Canada, the affected people have filed trial.
