Legionnaires' Outbreak Sickens Dozens on Upper East Side

Legionnaires' disease is caused by Legionella pneumophila, a bacterium that thrives in warm, damp environments such as cooling towers, air-conditioning systems, hot tubs, and large plumbing networks. People become infected only by breathing in contaminated water vapor or mist; the illness does not spread from person to person. Officials stressed that residents can still safely drink tap water, shower, cook, and run their home air conditioners. Dr Alister Martin, the city's health commissioner, called the chances of falling ill "extremely rare" but said the city had responded aggressively. Experts also link the rising frequency of such outbreaks to a warming climate, which creates more of the warm conditions in which the bacteria flourish. Past New York clusters have disproportionately affected poorer, predominantly Black and brown neighborhoods.

In response, the health department has sampled water from roughly 160 building cooling towers and ordered at least 19 buildings to drain, clean, and disinfect their systems. Investigators have not yet pinpointed the exact source, and officials cautioned that finding it could take another month; in many outbreaks the source is never identified. The bacteria pose the greatest danger to people over 50, smokers, and those with chronic lung disease or weakened immune systems. Doctors can treat the illness effectively with antibiotics, especially in its early stages. Authorities urged anyone who has recently been in the affected neighborhoods and develops flu-like symptoms — fever, chills, cough, or body aches — to seek medical care promptly, while stressing that residents should stay alert rather than alarmed.