New York City health officials ordered the immediate cleaning and disinfection of 10 rooftop cooling towers in the South Bronx after preliminary testing detected Legionella bacteria during a growing Legionnaires’ disease cluster. Nine people have become ill and one person has died.

The New York City Department of Health and Mental Hygiene identified the cluster after a surge in cases dating to late August. City health officials said tests found traces of Legionella in 10 of 24 sampled towers.

The affected structures include cooling towers at major locations such as Yankee Stadium and Lincoln Hospital. Officials ordered immediate remediation at the sites as public health workers moved to clean the equipment.

Initial testing relied on PCR, or polymerase chain reaction, which can return results quickly but cannot distinguish between live and dead bacteria. Culture tests can confirm whether bacteria are alive, but those results may take up to two weeks.

Because of that delay, city officials ordered the towers cleaned immediately as a precaution rather than waiting for culture results. The rapid response comes as experts point to recurring outbreaks and broader vulnerabilities affecting certain New York City neighborhoods.

Dr. Tyler Evans is CEO of the Wellness Equity Alliance and former first chief medical officer for New York City. He told Fox News Digital that outbreaks repeatedly appear in particular communities.

"When we look at outbreaks of Legionnaires' disease, in New York City, we almost always see it in the Bronx or Harlem," Evans said. "A lot of times, we see risk of infections taking place in historically marginalized communities."

Late summer weather may compound the danger inside industrial air conditioning systems. Evans said high temperatures can create ideal breeding conditions for bacteria in systems that add water to the surrounding air.

He said record temperatures can accelerate the risk as bacteria grow, become vaporized and create the potential for human exposure. Legionnaires’ disease spreads when people inhale contaminated vapor.

The illness is a severe form of pneumonia, but it cannot spread from one person to another. Evans also noted that people do not contract the disease by drinking tap water.

Most healthy people do not become sick after exposure, but certain groups can face severe health consequences. Evans said adults age 65 and older and people living with comorbid conditions should be especially concerned.

He identified diabetes, chronic obstructive pulmonary disease, also known as COPD, and compromised immune systems as underlying risk factors. These conditions can place exposed individuals at greater risk of serious illness.

Health officials urged anyone who has lived in, worked in or visited ZIP codes 10451 and 10456 since late August to monitor their health. The guidance applies to people with a connection to those areas during the period under investigation.

Symptoms requiring attention include high fevers, severe shortness of breath, chest pain and coughing up bloody mucus. Evans stressed that seeking medical attention early is important because the illness responds well to standard antibiotic treatment when detected promptly.

Evans explained that bacteria can be targeted with antibiotics, making Legionnaires’ disease treatable. "Bacteria are alive. Antibiotics are effective against bacteria because you can kill them, which makes it very treatable."

While city officials moved quickly to inspect and clean the towers, Evans said preventing future outbreaks requires sustained public investment. He raised the possibility of regularly testing cooling towers throughout New York City during periods of hotter weather.

"Could we test all cooling towers across New York City on a regular basis during times of risk when it's hotter? Yes," Evans said. He added that such work costs money and that reduced federal public health funding makes it difficult for local officials to expand efforts with fewer resources.

The investigation and cleaning orders remain focused on the affected South Bronx cooling towers while culture testing determines whether live bacteria were present. Fox News Digital contacted Yankee Stadium and Lincoln Hospital to request comment.