New York City health officials are investigating a Legionnaires’ disease cluster on Manhattan’s Upper East Side that has grown to 36 reported cases, according to local reports, as testing continues to identify the source of the outbreak.
The illness is a severe form of pneumonia caused by inhaling small droplets of water contaminated with Legionella bacteria. It does not typically spread from person to person. People can become sick after exposure to mist from building water systems, cooling towers, hot tubs, decorative fountains or plumbing systems where the bacteria can grow.
City investigators have focused in part on cooling towers, which are commonly used in large buildings and can disperse contaminated water vapor if not properly maintained. Health officials have been collecting samples and reviewing possible exposure sites in the affected area, according to the reports.
Legionnaires’ disease can cause cough, fever, chills, muscle aches and shortness of breath. Symptoms usually begin two to 14 days after exposure. The disease is treatable with antibiotics, but it can be serious, especially for adults 50 and older, current or former smokers and people with chronic lung disease, weakened immune systems or underlying medical conditions.
Cooling towers under scrutiny
Cooling towers have been linked to previous Legionnaires’ outbreaks in New York and other cities because they provide the warm, wet environment where Legionella can multiply. When contaminated water becomes aerosolized, people nearby may inhale the bacteria. Routine cleaning, disinfection and monitoring are key parts of prevention.
New York City has rules requiring building owners to register and maintain cooling towers. Those regulations were strengthened after earlier outbreaks, including a major 2015 outbreak in the Bronx. Even so, clusters can still emerge when equipment is poorly maintained or when environmental conditions allow bacteria to spread.
Health officials have not publicly confirmed a definitive source in the current Upper East Side cluster. Investigations of this type can take time because patients may have been exposed in different locations and because water sampling must be matched with laboratory testing.
Climate concerns add urgency
Public health experts have warned that climate change may contribute to a higher risk of Legionella growth by increasing temperatures and creating conditions that favor bacteria in built water systems. Heavy rain, flooding and infrastructure disruptions can also affect water quality, while longer warm seasons may extend the window for outbreaks.
The Centers for Disease Control and Prevention has reported that Legionnaires’ disease cases have increased nationally over the past two decades, though improved diagnosis and reporting may explain part of that rise. Urban density, aging infrastructure and widespread use of complex water systems also play a role.
Residents who live, work or spend time near the affected area are being urged to monitor for pneumonia-like symptoms and seek medical care if they become ill, particularly if they are at higher risk. Doctors can order urine or respiratory tests to help diagnose Legionnaires’ disease.
For now, the city’s investigation remains focused on identifying and remediating any contaminated source. Officials generally advise that drinking water is not the main concern unless it is aspirated into the lungs, and routine activities such as being near other people with the illness are not considered a transmission risk.
Key questions
- What is Legionnaires' disease?
- Legionnaires' disease is a serious type of pneumonia caused by breathing in water droplets contaminated with Legionella bacteria. It is usually treated with antibiotics and is not typically spread from person to person.
- Who is most at risk during a Legionnaires' disease outbreak?
- Adults 50 and older, smokers, people with chronic lung disease, those with weakened immune systems and people with certain underlying health conditions face a higher risk of severe illness.
