The New York City Health Department announced in late July that there was a cluster of Legionnaires’ disease outbreaks in Harlem, New York. Concentrated in five zip codes in Harlem: 10027, 10030, 10035, 10037 and 10039, the outbreak is not expected to reach other communities.

Health officials suspect the bacteria that cause the disease, Legionella, originated in a cooling tower. A cooling tower can cause Legionnaires’ disease when it becomes contaminated with Legionella bacteria and then releases them into the air through water droplets (aerosols) that people inhale.

According to an update on August 6 from the New York City Department of Health, “people living or working in the area with flu-like symptoms, such as cough, fever, chills, muscle aches, or difficulty breathing should contact a health care provider immediately.” The department warned that high-risk individuals, including those who are 50 and older, cigarette smokers, and people with chronic lung disease or compromised immune systems, should remain extra vigilant. Three people have died from the disease outbreak, and more than 20 have been hospitalized, according to the latest data from CNN.

Officials have made it clear that this outbreak is not due to an issue with the building’s plumbing system and that residents in these ZIP codes can continue to drink water, bathe, shower, cook, and use air conditioners.

According to the Occupational Safety and Health Administration, around 6,000 Legionnaires’ disease cases are reported each year in the United States. A recent whitepaper from Special Pathogens Lab, written by Dr. Janet Stout and Abraham Cullom,  between the mid-90s and around 2018, reported cases increased exponentially, partly due to better awareness and diagnosis, but the upward trend itself was still deeply concerning.

Cullom points out that categorizing Legionella as a "cooling tower disease" is a common misconception. “While cooling towers have been linked to high-profile outbreaks, most Legionnaires’ disease cases come from domestic water systems—showers, sinks, and plumbing in everyday buildings," he said.

"And while I’d always prefer to see a building over-reacting than under-reaching, some people tend to think that any Legionella presence is a cataclysmic threat. The reality is that it’s a normal part of our building water microbiomes, present in probably about 50% of large buildings. So, it’s something most of us live with regularly. Keeping an eye on it, keeping it under control, is the key to disease prevention, not necessarily chasing every positive everywhere down to zero.”