Health officials in New York City are sounding the alarm after confirming a Legionnaires’ disease outbreak on Manhattan’s Upper East Side, with 23 reported cases and 17 hospitalizations.

No deaths have been recorded so far, but authorities are warning residents to stay alert for symptoms of the potentially deadly bacterial pneumonia.

The New York City Health Department has urged anyone who has visited the east side of Central Park or nearby areas since late June to monitor their health closely.

Investigators are focusing on contaminated cooling towers as the likely source of the infection.

Here's What They're Not Telling You About Your Retirement

Officials emphasized that the disease is not spread from person to person and is unrelated to the city’s drinking water.

Legionnaires’ disease is caused by Legionella bacteria, which naturally occur in freshwater environments such as lakes and streams but can multiply in stagnant water systems.

According to the Centers for Disease Control and Prevention, the bacteria can grow in places where water has been standing for long periods, including shower heads, hot tubs, decorative fountains, plumbing systems, and cooling towers.

Infection can occur when people breathe in or swallow tiny water droplets that contain the bacteria.

This Could Be the Most Important Video Gun Owners Watch All Year

Dr. Alister Martin, New York City’s health commissioner, said in a press release, “Legionnaires’ disease is deadly but can be effectively treated if diagnosed early.” He encouraged those most at risk—people aged 50 and older, smokers, and those with chronic lung disease—to take any respiratory symptoms seriously and seek medical attention immediately.

Dr. Andrew Handel, a pediatric infectious disease specialist at Stony Brook Children’s Hospital, explained that Legionnaires’ symptoms resemble other forms of pneumonia.

Common signs include fever, cough, shortness of breath, and chest pain. Some patients also experience gastrointestinal issues like nausea and diarrhea, as well as confusion.

Symptoms usually develop between two and 14 days after exposure. Because the illness shares many characteristics with other respiratory infections, diagnosis typically requires laboratory testing and chest imaging.

Treatment involves antibiotics such as Levofloxacin or Azithromycin, according to experts. In mild cases, oral medications may be sufficient, but severe infections can require hospitalization for intravenous antibiotics, fluids, and breathing support.

Dr. Nathan Goodyear, an integrative medicine practitioner based in Arizona, described the infection as “intracellular,” emphasizing that “treatment needs to be early and aggressive.”

He said timely antibiotic therapy plays a critical role in preventing complications and saving lives.

The CDC estimates that roughly 10% of people infected with Legionnaires’ disease will die from related complications. The fatality rate climbs to around 25% among those who contract the disease while hospitalized or in long-term care facilities.

While no vaccine currently exists, public health experts stress prevention through the management of building water systems. The CDC recommends that property owners implement water management programs to minimize bacterial growth.

City officials reiterated their message to residents, encouraging high-risk individuals to promptly address any new respiratory symptoms. “New Yorkers at higher risk, including anyone who is 50 and older, those who smoke or people with chronic lung conditions should be especially mindful of their symptoms and seek care as soon as symptoms begin,” the health department stated.

For now, the investigation continues as health teams test potential water sources and monitor for new cases.

Officials said early recognition and fast treatment remain key to preventing severe outcomes from this outbreak.