Five people have died and 82 have been diagnosed in a Legionnaires' disease outbreak centered on New York City's Upper East Side, according to a report by Fox News. Eight patients remain hospitalized as of July 21.
Health officials said no new cases had been reported in the six days before that date, suggesting the source of exposure has likely been eliminated. The investigation remains ongoing.
Legionnaires' disease is a serious type of pneumonia typically spread by tiny water droplets containing Legionella bacteria, according to the Centers for Disease Control and Prevention. Common sources of infection include contaminated building water systems such as cooling towers, hot tubs, and plumbing. Cases have also been reported on cruise ships and in spas. The disease is not generally spread from person to person.
Dr. Dana Mordue, associate professor of pathology, microbiology and immunology at New York Medical College, explained how the bacteria enters the body.
"We get infected when it gets aerosolized in the water droplets, usually, and we breathe those droplets in," Mordue said. "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."
Mordue said that while home infection is possible, outbreaks are almost always linked to water droplets coming from a water system in a commercial-type building.
"The good news is you usually don't get it from the types of cooling systems that we have in our cars or our homes," she said. "But if you don't clean your humidifiers, technically any water source can get contaminated with Legionella."
Symptoms of Legionnaires' disease include cough, shortness of breath, fever, muscle aches, and headaches, according to the CDC. Some people may also experience diarrhea, nausea, and confusion. Symptoms typically appear two to 14 days after exposure. The illness often requires treatment with antibiotics.
Mordue said the risk is not equal across all groups.
"The mortality rate is not particularly high for this disease if you are immune-competent and young and healthy," she said.
Risk is higher for older adults, smokers, and people with compromised immune systems, "a lot of the same risk factors you might see for COVID," Mordue noted.
The CDC recommends that building owners maintain comprehensive water management programs to help prevent the spread of the bacteria. Those programs can reduce the conditions under which Legionella grows and spreads through building water systems.
