New York City health officials are investigating an outbreak of Legionnaires' disease on the Upper East Side that has resulted in five deaths and 82 confirmed cases, with eight patients remaining hospitalized. The New York City Department of Health and Mental Hygiene reported that no new cases had been recorded in the six days prior to July 21, suggesting the source of exposure may have been identified and mitigated, though the investigation is ongoing.
Legionnaires' disease is a severe form of pneumonia caused by Legionella bacteria, typically spread through airborne water droplets. Common sources include contaminated building water systems like cooling towers, hot tubs, and plumbing. The illness is not generally transmitted from person to person.
"We get infected when it gets aerosolized in the water droplets, usually, and we breathe those droplets in," explained Dr. Dana Mordue, associate professor of pathology, microbiology and immunology at New York Medical College. "You can also get infected if you have water that's been contaminated and you aspirate it and swallow it into your lungs, but most often you get it from air droplets that are contaminated from various types of water sources."
While exposure can occur at home, outbreaks are almost always associated with water systems in commercial buildings. Mordue noted that while residential humidifiers can become contaminated if not cleaned, typical home and car cooling systems are less likely sources.
Symptoms of Legionnaires' disease, which usually appear 2 to 14 days after exposure, include cough, shortness of breath, fever, muscle aches, and headaches. Some individuals may also experience diarrhea, nausea, and confusion. The illness is treatable with antibiotics, and early diagnosis is crucial for reducing the risk of severe outcomes.
"The mortality rate is not particularly high for this disease if you are immune-competent and young and healthy," Mordue stated. However, the risk is elevated for older adults, smokers, and individuals with compromised immune systems.
Preventative measures recommended by the Centers for Disease Control and Prevention focus on maintaining building water systems. Comprehensive water management programs can inhibit Legionella growth in cooling towers and plumbing. Routine cleaning, monitoring, and disinfection of cooling towers are advised. Preventing stagnant water by ensuring proper water flow and flushing infrequently used pipes can also help control bacterial multiplication. Maintaining appropriate water temperatures, ideally between 77°F and 113°F, and adequate disinfectant levels further limits bacterial growth.
Health experts urge individuals who may have been exposed and develop symptoms to seek immediate medical attention. Prompt diagnosis and antibiotic treatment are key to managing the illness, particularly for those with underlying health conditions or advanced age.