Guess where researchers found the bacteria that cause Legionnaires’ disease?
Now a researcher at Arizona State University has discovered that the bacteria can live in some brands of windshield washer fluid and flourish in the motor vehicle reservoirs that contain it. When sprayed, some of the droplets can be inhaled by vehicle occupants, especially people like bus drivers who are behind the wheel for extended periods.
Legionella pathogen thrives in windscreen wiper fluid, can find its way into vehicles, researchers say
The potentially deadly legionella pathogen can thrive in car windscreen wiper fluid, new research in the United States has found.
Arizona State University researchers examined a series of school buses across different seasons and found high concentrations of legionella bacteria in the fluid, which also found its way into the cabins of the buses at high levels.
Doctoral student Otto Schwake said the research uncovered some "pretty startling stuff".
"I was actually surprised by the positivity and concentration we were seeing," he said.
"Every single bus we looked at, on at least one sampling period, had live, culturable legionella."
Those recordings came from inside the fluid containers but "probably more disturbing" were the findings inside the buses after the windows had been sprayed, Mr Schwake said.
"When we performed air sampling while the buses were washing their windows, we found concentrations as high as 120 cells per cubic metre," he said.
"Just as a point of reference, a lot of outbreaks that occur for legionnaire's disease report concentrations from 10 to 200 ... so it falls within that range."
Mr Schwake said one bus was found to be carrying almost one billion legionella pneumophila, a known human pathogen species.
What is Legionella Pathogen
From Wikipedia, the free encyclopedia
The genus Legionella is a pathogenic group of Gram-negative bacteria that includes the species L. pneumophila, causing legionellosis (all illnesses caused by Legionella) including a pneumonia-type illness called Legionnaires' disease and a mild flu-like illness called Pontiac fever.
Legionella may be visualized with a silver stain or cultured in cysteine-containing media such as buffered charcoal yeast extract agar. It is common in many environments, including soil and aquatic systems, with at least 50 species and 70 serogroups identified. The bacterium, however, is not transmissible from person to person: furthermore, most people exposed to the bacteria do not become ill.
The side chains of the cell wall carry the bases responsible for the somatic antigen specificity of these organisms. The chemical composition of these side chains both with respect to components and arrangement of the different sugars determines the nature of the somatic or O antigen determinants, which are essential means of serologically classifying many Gram-negative bacteria.
Legionella acquired its name after an outbreak of a then-unknown "mystery disease" sickened 221 persons, causing 34 deaths. The outbreak was first noticed among people attending a convention of the American Legion—an association of U.S. military veterans. The convention occurred in Philadelphia during the U.S. Bicentennial year in July 21–24, 1976. This epidemic among U.S. war veterans, occurring in the same city as—and within days of the 200th anniversary of—the signing of the Declaration of Independence, was widely publicized and caused great concern in the United States.
On January 18, 1977, the causative agent was identified as a previously unknown bacterium subsequently named Legionella. See Legionnaires' disease for full details.
Sources of Legionella
Documented sources include cooling towers, swimming pools (especially in Scandinavian countries), domestic water systems and showers, ice-making machines, refrigerated cabinets, whirlpool spas, hot springs, fountains, dental equipment, soil,automobile windshield washer fluid, and industrial coolant.
Airborne transmission from cooling towers
The largest and most common source of Legionnaires' disease outbreaks are cooling towers (heat rejection equipment used in air conditioning and industrial cooling water systems) primarily because of the risk for widespread circulation. Many governmental agencies, cooling tower manufacturers, and industrial trade organisations have developed design and maintenance guidelines for controlling the growth and proliferation of Legionella within cooling towers.
Research in the Journal of Infectious Diseases (2006) provided evidence that L. pneumophila, the causative agent of Legionnaires' disease, can travel at least 6 km from its source by airborne spread. It was previously believed that transmission of the bacterium was restricted to much shorter distances. A team of French scientists reviewed the details of an epidemic of Legionnaires' disease that took place in Pas-de-Calais, northern France, in 2003–2004. Of 86 confirmed cases during the outbreak, 18 resulted in death. The source of infection was identified as a cooling tower in a petrochemical plant, and an analysis of those affected in the outbreak revealed that some infected people lived as far as 6–7 km from the plant.
Australian researchers set to help probe risk
While the high level of pathogens in the air is concerning, Mr Schwake says it is not yet conclusive that it is a significant risk and that it leads to people getting sick or dying from legionella.
"Whether or not it's posing a significant risk or even a risk at all we won't know until we do more research," he said.
The research says legionella is often under-reported, except in Australia where greater knowledge of the pathogen has led to higher reporting. Mr Schwake says Australian researchers are going to help test his findings.
"We actually have a nice collaboration hopefully going on with a public health group from Australia that are planning to look at sources of legionella transmission, including washer fluid," he said.
It is hoped the Australian group will help Mr Schwake identify whether this is a significant problem that needs to be investigated, or whether the fact that legionella survives in washer fluid is just an interesting anomaly with no significant public health concerns.
But given that winding up the windows appears to do little to protect against the pathogen's entry into a vehicle, Mr Schwake says it is a case of "picking your poison".
Other research has previously found windscreen washing fluids introduce potentially toxic levels of methanol into the cabin of cars.
Mr Schwake says legionella, which has previously been identified in air conditioners, water cooling towers and bags of potting mix, can also grow on air filters and even sterilizing the water is not a clear-cut solution.
"We chlorinate our water in America, probably in Australia as well, to reduce pathogens," he said.
"But legionella's unique in that ... a single cell gets past the treatment process, establishes a foothold in a new environment, and it can actually grow."
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