Testing has confirmed that the source of this summer’s second Legionnaires’ disease outbreak, which infected at least 13 people and killed 1 in the 10461 zip code of Bronx, New York, was a cooling tower at the Bronx Psychiatric Center.

Earlier in the summer, an initial large-scale outbreak in the South Bronx generated world-wide attention when it sickened more than 120 people and directly caused 12 fatalities. This outbreak was linked to the Opera House Hotel.

Timeline of New York’s Follow-up Actions

In response to the Legionnaires’ disease outbreaks in the Bronx, The New York City Department of Health and Mental Hygiene (DHMH) has launched a webpage, “Legionnaire’s Disease,” detailing the diagnosis dates and onset dates of disease clusters, providing a Legionnaires’ Disease Outbreak Timeline, and offering answers to questions residents might have about the outbreak.

July 20, 2015: After the first clusters of Legionnaires’ disease were reported to the Centers for Disease Control, the New York City Department of Health and Mental Hygiene (DHMH) initiate investigative processes.¹

July 28, 2015: Sampling of suspected cooling towers begins.²

August 5, 2015: The Bronx Psychiatric Center starts testing its cooling tower for Legionella in compliance with newly issued city and state regulations.³

August 17, 2015: Tests of the Bronx Psychiatric Center yield negative results for Legionella.⁴

August 20, 2015: The historic Opera House Hotel is officially declared the source of the first Bronx outbreak.⁵

September 2015: 13 people become ill in the second, zip code 10461 (Morris Park) outbreak; 1 dies.⁶

November 20, 2015: NYC DHMH confirms the Bronx Psychiatric Center as the most likely source of the 2^nd outbreak: “After extensive sampling of cooling towers and testing of Legionella Bacteria, the city’s Public Health Laboratory, in collaboration with the state’s Wadsworth Center laboratory, identified a cooling tower at the Bronx Psychiatric Center as the likely source of the outbreak. The Legionella strain found in the cooling tower matched samples taken from four patients.”⁷

Why Is Legionella Control So Essential?

As this summer’s Bronx fatalities prove, it is essential that building owners provide ongoing and thorough maintenance and testing of their water systems in order to avoid the proliferation of Legionella. The bacteria can colonize very quickly, given the right conditions:

“In general, the concentrations of Legionella bacteria in building water supplies are very low. They may not be detectable in routine sampling and testing of the water supply. However, a small amount of Legionella bacteria may colonize the water system if they find their way into the system. Older water systems are more likely to have Legionella colonization because of thicker biofilm buildup and the increased probability that Legionella bacteria may reach the system.”⁸

This is particularly true in high-density urban areas where the potentially deadly bacteria, once aerosolized by aging cooling towers, can travel more than 4 miles, infecting populations weakened by respiratory diseases, smoking, and other underlying medical conditions.

Sources:

1. “Major Events in South Bronx Legionnaires’ Disease Outbreak.” Legionnaires’ Disease, New York City Department of Health and Mental Hygiene. Web. 2 Dec. 2015 (date of access).
2. Ibid.
3. “Bronx Psychiatric Cooling Tower Blamed for Morris Park Legionnaires’ Outbreak.” CBSNewYork. Web. 20 Nov. 2015.
4. Ibid.
5. “Major Events in South Bronx Legionnaires’ Disease Outbreak.” Legionnaires’ Disease, New York City Department of Health and Mental Hygiene. Web. 2 Dec. 2015 (date of access).
6. “Legionnaires’ Disease Cluster in Morris Park, Bronx.” Legionnaires’ Disease, New York City Department of Health and Mental Hygiene. Web. 2 Dec. 2015 (date of access).
7. “Press Release #055-15: Health Department Identifies Likely Source of East Bronx Legionnaires’ Disease Outbreak.” New York City Department of Health and Mental Hygiene. Web. 20 Nov. 2015 (2 Dec. 2015 date of access).
8. Yang, CS. “Sampling and Controlling Legionella Bacteria in Domestic Water Systems,” EM Lab P&K: 1-6. 2004. https://www.emlab.com/media/resources/Sampling-Controlling-Legionella-Domestic-Water-System.pdf