Outbreaks of Legionnaire’s disease are most often linked to large-scale air conditioning systems, but new research shows that automobile windshield washers can harbor the Legionella bacteria for long periods and release potentially dangerous numbers of these bacteria into the air. The findings, presented yesterday at the annual meeting of the American Society for Microbiology, suggest that automobiles may serve as a source of transmission for Legionellainfections.
Legionella are bacteria that are found naturally in the environment, usually in water. In humans, Legionella can trigger respiratory illness, including the deadly pneumonia known as Legionnaire’s disease. The bacteria are not spread from person to person, but instead are transmitted via mist or vapor containing the bacteria. Most people exposed to the bacteria do not become ill, but in some people it can cause Legionnaires’ disease, a severe form of pneumonia. The bacteria can also cause Pontiac fever, a milder illness that resembles the flu.
The new findings come from a series of experiments conducted by Arizona State University researcher Otto Schwake in 2012. Schwake and his colleagues attempted to grow Legionella bacteria in a variety of different washer fluid preparations. They found that the bacterial concentrations increased over time and they were able to maintain stable populations for up to 14 months. In a second related study, Schwake tested the washer fluid from school buses in central Arizona and found culturable Legionella in around 75 percent of the samples.
“This study is the first to detect high levels of Legionella in automobiles or aerosolized by washer fluid spray,” says Schwake. “These results suggest that automobiles may serve as a source of transmission for Legionella infections. 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.”