NYC Legionnaires’ Outbreak Reaches 90 Cases, Spurs Proposed Cooling Tower Rules

Health officials in New York City reported Monday that a Legionnaires’ disease cluster in Central Harlem has expanded to 90 cases, with three confirmed fatalities.

The announcement follows a recent proposal from the city’s health department for stricter testing regulations on cooling towers, which are suspected to be linked to the outbreak.

Cooling towers, found on rooftops of large buildings, release mist as part of the cooling process. If the water within them becomes warm, stagnant, or inadequately disinfected, Legionella bacteria can grow and spread to people who inhale the mist.

A health department spokesperson told CNN the new testing rules “were in development well before the Legionnaires’ cluster in Central Harlem.”

Under current New York City law, building owners must register and maintain cooling towers, which are routinely inspected. The proposed changes would set specific testing intervals, require samples to be analyzed by state-certified labs, and impose financial penalties for noncompliance. The proposal did not specify the penalty amounts, but currently, failing to follow routine maintenance can result in fines from $500 to $2,000.

Enforcing the proposed rules may prove difficult. City data shows inspection numbers dropped to a record low in 2024—less than half the total conducted in 2017, when records began. Gothamist first reported the decline.

Officials first disclosed the current Legionnaires’ cluster on July 25. They say every operational cooling tower in the affected area has been tested, and any that tested positive for Legionella were ordered cleaned. The department confirmed the required cleanings were completed.

Legionnaires’ disease presents with flu-like symptoms, including cough, fever, headaches, muscle aches, and shortness of breath. It can be treated with antibiotics, but untreated cases may progress to shock and multi-organ failure. The World Health Organization notes that older adults and people with weakened immune systems are at greater risk, and the US Centers for Disease Control and Prevention estimates that about 10% of patients die from complications.