Fifty-eight people have been infected—and two have died—in a New York City outbreak of Legionnaires’ disease—a severe type of pneumonia caused by a bacterium commonly associated with air-conditioning

An outbreak of Legionnaires’ disease in New York City has killed two people and sickened 58 since late July. City health officials link the Central Harlem outbreak to cooling towers, structures containing water and a fan that are used to cool buildings.

Legionnaires' disease is caused by Legionella, a bacteria that can travel through water systems and devices. Although most healthy people don't contract it, it can be deadly for those who do.