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Windshield washer fluid possible exposure route for Legionnaires' disease
Researchers have identified windshield washer fluid as a possible source of Legionella, according to data presented at the 2014 General Meeting of the American Society for Microbiology.
“Washer fluid spray can release potentially dangerous numbers of these bacteria into the air,” study researcher Otto Schwake, a PhD student at Arizona State University, said in a press release. “These results suggest that automobiles may serve as a source of transmission for Legionella infections.”
Legionella has been found to flourish in vapor generated from engineered water systems. Specifically, cooling tower vapor was implicated as the primary source of human transmission in a 2013 outbreak in Milwaukee. However, there have been several epidemiological studies that found that automobiles were associated with increased risk for the disease as well. According to one report published in the European Journal of Epidemiology, one in five community-acquired cases of Legionella in the United Kingdom can be attributed to exposure to windshield washer fluid. These studies prompted Schwake and colleagues to investigate the potential for washer fluid serving as a source of exposure.
In their study, the researchers inoculated several types of washer fluid with L. pneumophila and found that concentrations of the bacteria increased with time and maintained stable populations for up to 14 months. Survival rates were higher in one particular type of washer fluid compared with sterile water, they said.
Schwake and colleagues also conducted an additional field study that tested the washer fluid collected from school buses in central Arizona. Curable Legionella bacteria were isolated in approximately 75% of the buses sampled, with L. pneumophila concentrations as high as 1.5x105 colony-forming units/mL.
“This study is the first to detect high levels of Legionella in automobiles or aerosolized by washer fluid spray,” Schwake said. “While potential transmission of a deadly respiratory disease from a source as common as automobile windshield washing systems is significant, the study also points to the fact people can be exposed to pathogens — particularly those occurring naturally in the environment — in previously unknown and unusual ways.”
For more information:
Schwake O. Abstract 135. Presented at: 2014 General Meeting of the American Society for Microbiology; May 17-20, 2014; Boston.
Wallensten A. Eur J Epidemiol. 2010;25:661-665.
Disclosure: The researchers report no relevant financial disclosures.