New York City health officials are investigating a Legionnaires’ disease outbreak in Harlem that has left one person dead and 22 others sick. The cluster, first detected on July 25, spans five Harlem ZIP codes—10027, 10030, 10035, 10037, and 10039—and bordering communities.
Legionnaires’ is a severe form of pneumonia caused by inhaling water vapor contaminated with Legionella bacteria, which thrive in warm water systems like cooling towers, hot tubs, humidifiers, and large-scale air-conditioning units. The NYC Health Department has tested all cooling towers in the affected area and ordered immediate remediation in any buildings with positive results.
Officials are urging anyone who has been in the area since late July and is experiencing flu-like symptoms, fever, cough, or difficulty breathing to seek medical attention immediately. Legionnaires’ is not spread person-to-person and is treatable with antibiotics, though it often requires hospitalization.
Those at highest risk include adults over 50, smokers, and people with chronic lung conditions or weakened immune systems. “Early detection and treatment save lives,” the Health Department stressed in its warning.
Legionnaires’ symptoms typically appear within two to 10 days of exposure and can mimic COVID-19 or the flu, making testing crucial. A milder form, known as Pontiac fever, can also develop, presenting with similar symptoms without causing pneumonia.
This is not New York’s first encounter with the deadly bacteria. In 2022, a Manhattan nursing home outbreak killed five, and in 2015, a Bronx cooling tower outbreak led to 16 deaths—the city’s deadliest to date.
With an average of 200–700 cases annually, officials are reminding New Yorkers to stay alert. Anyone experiencing symptoms and with recent exposure to hot tubs, cooling towers, or large water systems in the affected area should contact a doctor immediately.
