New York City reports first death in Legionnaires outbreak

Central Harlem’s Legionnaires outbreak reached its first death as New York City health officials traced a water source and warned residents. The cluster, centered in Central Harlem, was tied to contaminated building systems and could turn severe fast in older adults, smokers and people with weakened immune systems.

Legionnaires’ disease is caused by Legionella bacteria, which thrive in warm water and can travel in mist from cooling towers, air-conditioning systems, hot tubs, decorative fountains and other large plumbing systems. The illness is usually not spread from person to person, so the main public-health defense is environmental, finding the contaminated equipment, cleaning it and stopping more exposure. Anyone with fever, cough, shortness of breath or muscle aches should get medical care quickly, since early treatment matters.

The Harlem outbreak began after the first case was identified on July 25, 2025. NYC Health said 58 people had been diagnosed and two people had died since that date. By Aug. 14, NYC Health said the cluster had reached 99 cases and four deaths. The outbreak involved city-run buildings, including a hospital.

City health officials said all operable cooling towers in the investigation area were being sampled and remediated if contaminated. In New York City, which typically records 200 to 700 Legionnaires’ diagnoses each year, NYC Health described the Harlem episode as the city’s largest Legionnaires’ outbreak in a decade.