What’s known so far

According to local health authorities and media reports, at least 35 people have been diagnosed with Legionnaires’ disease in Westchester County, and two individuals have died. Investigators are tracing potential environmental sources, such as cooling towers and building water systems, and advising residents—especially those at higher risk—to watch for symptoms and seek medical care if they feel unwell.

Clusters of Legionnaires’ disease are not uncommon in densely populated areas with large building infrastructure. New York State has some of the strongest Legionella control regulations in the country, and when cases rise, public health teams typically move quickly to sample water systems and implement control measures.

What is Legionnaires’ disease?

Legionnaires’ disease is a form of pneumonia caused by Legionella bacteria, most often Legionella pneumophila. People become ill by inhaling small droplets of water (aerosols) that contain the bacteria. It is not spread by drinking water, and it generally does not spread from person to person.

Legionella lives in natural freshwater environments but can grow to dangerous levels in man-made water systems if those systems are not properly designed, maintained, and disinfected.

How Legionella spreads

• Inhalation of aerosolized water from sources like cooling towers, decorative fountains, showers, hot tubs, and misting systems.
• Exposure to building plumbing where warm water can stagnate and disinfectant levels are inadequate.
• Less commonly, aspiration of water (accidentally swallowing water “down the wrong pipe”), typically among people with swallowing difficulties.

Legionella does not spread via casual contact. Everyday activities like drinking tap water are not typically a risk for infection; the risk comes from breathing in contaminated mist.

Symptoms and when to seek care

Symptoms usually begin 2–14 days after exposure and can include:

• Fever, chills
• Cough (can be dry or productive), shortness of breath, chest pain
• Muscle aches, headache, fatigue
• Gastrointestinal symptoms such as nausea, vomiting, or diarrhea
• Confusion in older adults

Seek medical care promptly if you develop pneumonia-like symptoms, especially if you are older than 50, smoke, have chronic lung disease, are immunocompromised, or were recently exposed to large buildings, healthcare facilities, or devices that produce water mist. Tell your clinician that Legionnaires’ disease has been reported locally—this can guide testing and treatment decisions.

Who is most at risk?

• Adults over 50
• Current or former smokers
• People with chronic lung disease (COPD, emphysema, asthma)
• People with weakened immune systems or on immunosuppressive medications
• Those with chronic illnesses such as diabetes, kidney disease, or cancer

While healthy people can become ill, severe disease and complications are more likely in these groups.

What authorities are doing

Public health responses to a Legionnaires’ cluster typically include:

• Case interviews to map where patients live, work, and visited during the incubation period.
• Environmental sampling of likely sources such as cooling towers, large building plumbing, fountains, and hot tubs.
• Immediate control measures (e.g., disinfection, system shutdowns, hyperchlorination, thermal shock) when a source is suspected or confirmed.
• Notifications to building owners and facility managers about required maintenance and testing under New York State regulations.
• Public advisories with guidance for residents, healthcare providers, and congregate settings.

New York’s cooling tower rules require registration, routine Legionella testing, and corrective actions when results exceed thresholds. Hospitals and nursing homes also follow water management standards designed to reduce risk.

What residents can do right now

• Know the symptoms and act early if you feel ill. Prompt antibiotics improve outcomes.
• If you haven’t used certain taps or showers recently, run hot water for several minutes with good ventilation before use. Clean showerheads and faucet aerators.
• Set home water heaters to at least 120–140°F (49–60°C) if safe to do so; use anti-scald measures and caution to prevent burns.
• Maintain and regularly disinfect humidifiers, CPAP/BiPAP humidifiers, and portable misters; use distilled or sterile water, not tap water.
• Avoid sitting close to visible mists (e.g., from decorative fountains) until authorities provide further guidance.
• If you manage a multi-unit residence, review your water management plan and communicate with your water service professionals.

These steps are general risk-reduction measures. Follow any specific instructions provided by local health officials during the investigation.

Guidance for building owners and managers

Large buildings, healthcare facilities, and sites with complex water systems should ensure that water management plans are current and implemented. Key elements include:

• Maintaining hot water temperatures and cold water temperatures within recommended ranges to limit Legionella growth.
• Maintaining disinfectant residuals and monitoring routinely.
• Preventing water stagnation by flushing low-use outlets and balancing the system.
• Regularly cleaning and replacing fixtures, showerheads, and aerators.
• Cooling tower maintenance: registration, routine Legionella testing, proper biocide programs, inspection, and documentation.
• Corrective actions (e.g., hyperchlorination, thermal disinfection, copper-silver ionization) when thresholds are exceeded.

If your building is contacted by health authorities, respond promptly, provide access for sampling, and implement interim control measures as directed.

How investigators identify the source

Public health teams look for overlap in where patients spent time during the incubation window. Suspect sites are sampled, and laboratory testing is performed to detect Legionella. When possible, bacteria isolated from patients are compared to environmental samples using molecular methods to confirm a match. Because multiple sources can be positive for Legionella, the combination of epidemiology, environmental results, and timelines guides decisions about remediation and public communication.

Treatment in brief

Legionnaires’ disease is treated with antibiotics prescribed by a clinician, commonly a macrolide (such as azithromycin) or a respiratory fluoroquinolone (such as levofloxacin). Many patients require supportive care, and severe cases may need hospitalization. If you have symptoms, do not delay seeking care.

Frequently asked questions

Is my tap water safe to drink?

Yes. Legionella risk is from inhaling contaminated mist, not from drinking water. People with high risk should avoid creating aerosols (very hot steamy showers) until more is known.

Should I buy bottled water?

Not for Legionella risk. Bottled water is not necessary unless directed by officials for other reasons.

Can I catch it from someone who is sick?

Person-to-person spread is exceedingly rare. Legionnaires’ disease is generally acquired from environmental water sources.

Do home air conditioners spread Legionella?

Standard window or split-unit air conditioners do not aerosolize water and are not a typical source. Large building cooling towers, which use water for heat rejection, can be a source if not properly maintained.

Staying informed

For authoritative updates, consult announcements from the Westchester County Department of Health and the New York State Department of Health. Healthcare providers will receive clinical guidance through official health alerts.

Because investigations evolve quickly, details such as the number of cases, affected neighborhoods, and identified sources may change as new information emerges.