Legionnaires Disease in NYC and the Plague in Yosemite. The microbes are restless this summer. Must be the heat that has put them in a frenzy. Plague is caused by Yersinia pestis, a bacterium that is carried by fleas that transmit it to human or other mammals when they feed. Plagues was called the Black Death in the Dark Ages and is estimated to killed up to 200 million people between the years 1346–1353.
Legionnaires Disease is caused by bacteria in the genus Legionella. People contract it by breathing in airborne Legionella vegetative cells that become aerosolized from common sources such as cooling towers, sinks, showers and hot tubs. It is also known to colonize the lines of ice machines and in-line water fountains.