In 1976, thirty-four members of the American Legion attending a convention in Philadelphia mysteriously died from pneumonia-like symptoms. More than two hundred others were sickened but recovered. Medical authorities were initially baffled. A month later, as this Science News piece shows, they were still racing to find the cause: was it a virus, a weed-killer, cadmium, or some other poison (intentional or not)? The report’s “No signs of a bacterium” however, proved to be immature.

It turned out to be bacteria. The American Legion gave its name to both the common name of the disease and the genus name of the bacteria that causes it, Legionella. Since then, Legionnaire’s Disease has periodically struck across the world, most recently in the Bronx, NY, where twelve people died this month.

The disease is rare, however, with fewer than 20,000 U.S. cases per year. Those at the highest risk include males, smokers, the immunosuppressed, and people with chronic disease. But Legionnaire’s tends to make headlines, perhaps because its method of transmission seems insidious; the bacteria spreads through aerosolized water particles from air conditioning systems, cooling towers, fountains, misting systems, showers, whirlpools, humidifiers, and the like. The inhalation of contaminated water droplets delivers the bacteria to the lungs.

But this European Journal of Epidemiology study notes that sources of the disease are rarely identified for sporadic cases of the disease. In their case study, they pinpointed windshield wiper fluid as a potential source of contamination when it doesn’t contain a detergent screenwash. (Most American windshield wiper fluids seem to come with detergents included.)

This study corresponded to other studies of professional drivers in both the Netherlands and Japan. The EJW authors concluded with some simple public heath advice: “We estimate that 20% of community acquired sporadic cases under the age of 70 years in England and Wales could be prevented by using screen wash.” This sounds somewhat akin to the time-tested advice of washing your hands.