What is the unusual medical name for the fatal disease which appeared in 1976 among persons attending a convention in Philadelphia?

The name of this severe, pneumonia-like illness is a direct reference to its first identified victims. In the summer of 1976, a mysterious and deadly respiratory sickness broke out among people attending an American Legion state convention at a hotel in Philadelphia. As the media reported on the frightening outbreak, which sickened over 200 people and ultimately caused 34 deaths, the press and investigators began referring to it by the name of the group most affected. The term stuck, becoming the official name for the new disease.

It took months of intense investigation by the Centers for Disease Control and Prevention (CDC) to finally isolate the culprit: a previously unknown bacterium. It was fittingly named *Legionella pneumophila*, with *pneumophila* being Greek for "lung-loving." The bacteria thrive in complex man-made water systems, and the 1976 outbreak was traced to the hotel's air-conditioning cooling tower. The disease spreads not from person to person, but through the inhalation of contaminated water vapor or mist from sources like cooling towers, hot tubs, and large plumbing systems. This landmark epidemiological investigation transformed how public buildings manage their water systems to prevent future outbreaks.