---
title: Most Legionnaires' Cases Never Get the Scrutiny New York's Outbreak Received
description: New York tested 183 cooling towers to close its Upper East Side Legionnaires' cluster, while a coalition says 96 percent of US cases are single infections.
author: Dr Marina Nani (Editor-in-Chief)
updated: 2026-08-11T23:16:56.429Z
canonical: https://richhealthmagazine.com/article/legionnaires-sporadic-cases-nyc-cooling-towers
image: https://cdn.nanimediahouse.com/rooftop-cooling-towers-illustration-140658.webp
categories: Everyday Wellness
content_type: Analysis
region: United States
publication: Rich Health Magazine
schema_type: Article
---

New York City's health department has closed its investigation into the Legionnaires' disease cluster that spread through the Upper East Side this summer. Ninety two people tested positive in the Carnegie Hill and Yorkville neighborhoods, ZIP codes 10028, 10128 and 10075, and seven of them died. No case has been diagnosed since July 21, and the department says it is confident the source of the bacteria has been eliminated.

Legionnaires' disease is a form of pneumonia caused by Legionella bacteria that grow in warm water and reach people through mist they breathe in. The health department says it is not contagious and cannot be caught from another person, from drinking water, from cooking, or from the cooled air an air conditioner produces.

## Inspectors Tested 183 Cooling Towers Across Three ZIP Codes

The department [tested 183 cooling towers at 160 buildings](https://www.nyc.gov/site/doh/health/health-topics/legionnaires-disease.page). Seventy seven towers at 75 buildings came back positive on the initial screen, and 59 towers at 58 buildings then tested culture positive, meaning live bacteria rather than genetic traces. All 59 have been cleaned and disinfected, and the remaining 124 towers tested negative. A culture positive tower may or may not have been the source of anyone's exposure, the department notes. Of the people who fell ill, 67 have left hospital, 13 were never admitted and five were still being treated when the final update went out on July 30.

## Almost All Cases in the Country Happen One at a Time

Outbreaks are the visible part of the disease. The Alliance to Prevent Legionnaires' Disease, a nonprofit coalition of health advocates, providers, building engineers, scientists, water treatment experts and manufacturers, says that about 10,000 cases are reported in the United States each year, citing the CDC, and that the real figure is likely higher because the disease is underdiagnosed. About one in ten people who fall ill die of complications. The coalition puts the share of cases that are single or sporadic, rather than part of a recognized cluster, at 96 percent, and says those cases seldom get the kind of investigation New York has just finished.

Dr. Hung Cheung, a board member and medical advisor at the alliance who teaches at the University of Pennsylvania's Perelman School of Medicine and previously served as Maryland's state medical director, said the science has moved further than the response. "Fifty years after the historic outbreak that first brought Legionnaires' disease to the nation's attention, we know far more about how it spreads but we must take a more integrated, holistic approach to this waterborne disease," Cheung said. The illness took its name from a 1976 outbreak among people attending an American Legion convention in Philadelphia.

Gwen Hanlon, a volunteer with the alliance whose husband Kevin died of the disease, said no family should have to experience a preventable loss.

## New Jersey Wrote a Source to Tap Approach Into Law in 2024

The alliance wants water utilities, building owners and public health agencies to treat prevention as one chain, from source water through treatment plants and distribution networks to the plumbing and water equipment inside a building. New Jersey passed legislation along those lines in 2024, and the group says similar bills have since been introduced in New York, Pennsylvania and Maryland. Passing a law is not the same as enforcing one, it argues, and implementation is where prevention tends to fall down.

## FAQ

**Q: What is Legionnaires' disease?**
A type of pneumonia caused by Legionella bacteria that grow in warm water. It brings on flu like symptoms, and complications can be serious or fatal if it goes untreated.

**Q: Can you catch it from another person?**
No. New York's health department says the disease is not contagious, and that you cannot get it from drinking water, from cooking or from the cooled air an air conditioner produces.

**Q: How do people become infected?**
By breathing in water vapor that carries the bacteria. Most people who are exposed do not fall ill, and illness usually follows high or repeated exposure, especially among people already at increased risk.

**Q: Is the New York cluster still spreading?**
No. The health department says no case has been diagnosed since July 21 and that transmission tied to the cluster has ended, though it describes its data as preliminary.