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Published: August 20, 2025
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In Healthbeat, Dr. Jay Varma reflects on New York City’s second-largest outbreak of Legionnaires’ disease — more than 100 people sickened and five deaths — and draws lessons from the city’s 2015 South Bronx outbreak, which he led as incident manager. Varma explains how cooling towers became recognized as a major source of airborne Legionella bacteria, why regulations requiring registration, quarterly testing, and remediation were passed in 2015, and how reduced inspections during COVID and staffing shortages have left the city vulnerable once again. His central message: infections may be inevitable, but outbreaks are preventable — if regulations are enforced and public health is adequately funded.
A Deadly Reminder of 2015
The latest Legionnaires’ disease outbreak in New York City — the second largest in the city’s history — recalls the summer of 2015, when 138 people were infected and 16 died. That crisis, traced to a South Bronx hotel cooling tower, forced the city to acknowledge a long-ignored risk: poorly maintained cooling towers as vectors of disease.
What Is Legionnaires’ Disease?
Legionnaires’ disease is a severe pneumonia caused by Legionella bacteria. It is not transmitted person-to-person, but rather through inhaling contaminated water droplets, often from cooling towers, hot tubs, or large plumbing systems. Older adults, smokers, and people with chronic illness are at highest risk.
How Cooling Towers Spread Infection
Cooling towers expel mist into the environment as part of building air-conditioning systems. If Legionella grows in the tower’s warm, stagnant water, it can be dispersed into the surrounding community. Because DNA fingerprinting is required to prove the link between environmental and human samples, outbreaks often go undetected until many people fall ill.
“Infections may be inevitable, but outbreaks are a choice.” —Dr. Jay Varma
The 2015 Outbreak and New Regulations
The South Bronx outbreak triggered New York City’s first-ever regulations requiring:
- Registration of all cooling towers with the Health Department
- Quarterly water testing and mandatory remediation if Legionella was detected
- Dedicated city inspectors to enforce compliance
Within a year, nearly 80% of towers were inspected, contamination was reduced, and large outbreaks disappeared — until now.
Inspections Fall, Outbreaks Return
COVID-19 diverted resources, routine inspections dropped, and staffing never fully rebounded. In 2025, inspection numbers fell to their lowest since the law passed. Following this year’s outbreak, 11 towers tested positive for Legionella, including several operated by city agencies and hospitals.
Outbreaks Are a Choice
Varma underscores a fundamental truth: public health protection requires sustained investment and enforcement. Regulations are only as effective as the systems that uphold them. With government budgets slashed and authority weakened, preventable outbreaks become inevitable. “Infections may be inevitable, but outbreaks are a choice,” he writes.
📅 Publication Date & Outlet
August 20, 2025 | Healthbeat (Guest Essay by Dr. Jay K. Varma)
Read the full essay on Healthbeat
Source note
Original source: What we learned from NYC’s 2015 Legionnaires’ outbreak about cooling towers and inspections, published August 20, 2025.
Related reading
- Building Relationships Before the Next Outbreak
- Legionnaires’ disease outbreaks and cooling towers, New York City, New York, USA
- A large community outbreak of Legionnaires’ disease associated with a cooling tower in New York City, 2015
