City health officials say they are still investigating a cluster of cases of a poorly understood type of pneumonia known as Legionnaires’ disease.
As of July 6, there were 23 confirmed cases in two Upper East Side neighborhoods, Carnegie Hill and Yorkville. Of those, 17 people have been hospitalized, according to the New York City Department of Health.
The disease can cause flu-like symptoms such as cough, fever or trouble breathing. In some cases, it can lead to severe pneumonia and be fatal, even when treated. People 50 and older and those who smoke or vape, have chronic lung disease or are immunocompromised are more at risk of both contracting Legionnaires’ disease or developing severe illness.
How it’s caused and investigated
Legionnaires’ disease is caused by people breathing in mist contaminated by Legionella bacteria. In the warm water found in cooling towers, hot tubs and spray fountains, the bacteria can grow and spread to humans through the mist they produce if the water systems are not properly cleaned and maintained.
When city health officials investigate community clusters, they’re largely looking for the source of the contamination, with the goal of preventing more people from getting sick. Their tool: a requirement that building owners register cooling towers. Owners are also required to conduct routine Legionella bacteria testing of water in cooling towers and inspect the systems.
If you live in a New York City building, you can look up Health Department inspection results for cooling towers by address or building ID here.
No need for most people to worry “excessively”
City health officials say New Yorkers experiencing flu-like symptoms who live or work in Carnegie Hill and Yorkville or have visited them since late June should contact a health care provider immediately. While there’s no vaccine or preventive medication for Legionnaires’ disease, it can be treated with antibiotics, which are more effective if treatment is begun early.
When Epicenter NYC spoke with infectious disease experts on Monday, they cautioned people outside these neighborhoods against panicking.
“I don’t think people should be excessively worried about it,” said Dr. Aaron Glatt, professor and chairman of the Department of Medicine at Mount Sinai South Nassau in Oceanside. “Even one case is too many, but this relatively small cluster […] in a very specific neighborhood, it’s probably due to a very specific exposure.”
He added that while Legionnaires’ can develop elsewhere, “right now we have no evidence that it is occurring in other places. So people that aren’t in that direct area really are no more at risk for it than at any other time.”
Epicenter also spoke with Dr. Andrew Handel, pediatric infectious disease specialist at Stony Brook Children’s Hospital on Long Island, about what else to keep in mind while the city investigates this cluster. Excerpts of the conversation below have been edited for clarity and length.
Epicenter NYC: For the average New Yorker who’s seeing all these headlines about another outbreak — NYC experienced one last summer — how worried should people be about this Legionnaires’ cluster right now?
Dr. Handel: I don’t think this is a reason for people to have extreme alarm. Of course, it’s concerning, and we need to monitor for additional cases. Those who are in the area where cases have been identified should self-monitor for any symptoms that can suggest the infection.
Epicenter NYC: For anyone who works or lives in the area, is there anything preventive they can do? Is there any evidence that an N95 mask while walking around might help minimize exposure to the mist?
Dr. Handel: It hasn’t been studied to say those are particularly effective, but it’s not unreasonable to think [N95 masks] could provide some protection.
That said, it’s not something we standardly recommend. It’s also been very hot and very humid, and wearing a tight-fitting mask can make it more difficult to breathe in those conditions. You have to weigh the risks and benefits.
The Department of Health and the CDC have not recommended that people wear masks to prevent these infections.
Epicenter NYC: So for people who live in that area or can’t avoid it, what are some ways to minimize exposure?
Dr. Handel: The key is really the Department of Health conducting its investigation as quickly as possible to get to the bottom of where this is coming from and address that water source.
Since we’re seeing 18 cases, that actually makes it easier for investigators to focus on exactly where the exposures may have occurred. Legionella is not contagious from person to person. It’s likely the people who were affected were walking by some shared contaminated water system. When you have that many people, it makes it easier to locate exactly where that is.
Epicenter NYC: If you work or live in the area, would you recommend trying to stay indoors as much as possible?
Dr. Handel: It’s difficult to make a recommendation like that. One thing to keep in mind is who’s actually at risk. Many of us come across Legionella from time to time and never know we were exposed because it’s an opportunistic infection. It primarily affects people who are at higher risk.
That includes people over 50, smokers and people with lung disease. In those circumstances, the bacteria has an opportunity to get into the lungs and cause a severe infection.
Epicenter NYC: It has that opportunity because the immune system isn’t working as well to keep out a pathogen?
Dr. Handel: Exactly. For people who are otherwise healthy and not in that older age group, if we come across the bacteria, our immune system is able to fight it off before it causes a problem.
People with compromised immune systems have less ability to fight it off if they inhale the bacteria. People with chronic lung disease or smokers have microscopic damage to the lungs that makes it easier for the bacteria to invade once it’s been inhaled. Those risk factors are important when we’re thinking about how concerned someone should be.
For people living in the area who have those risk factors, it’s difficult to say they should never go outside until this is figured out. If they’re most comfortable wearing a mask, I don’t think that’s unreasonable. They just have to weigh that against the challenges of wearing a tight-fitting mask when the weather is already making it difficult for some people to breathe.
Epicenter NYC: For people who go to gyms, saunas, spas or steam rooms, is there anything they should know about Legionnaires’ risk?
Dr. Handel: If you’re exposed to those water systems, it’s a bit of a conundrum because you’re really at the whim of the location that’s maintaining that water system, hot tub or sauna. Could you get Legionella from those areas? Absolutely. It’s warm, moist air that’s aerosolized from water systems that spreads it. The key is proper maintenance of those water systems.
For someone going to the gym and spending time in the sauna, there’s only so much they can do to prevent it. If you’re immunocompromised, spending time in a sauna may pose health risks that you may choose to avoid.
Epicenter NYC: Or if you’re over 50 or have other risk factors?
Dr. Handel: It’s difficult to tell everyone over 50 to stop using saunas. The key is that the business or organization maintaining that water system makes sure it’s up to code and properly maintained. If you have risk factors for Legionella, you can choose to avoid those locations.
Epicenter NYC: Why does it seem like Legionnaires’ disease keeps coming back in New York even after regulations and inspections?
Dr. Handel: I think it’s a factor of how large the city is and how many different water sources can become contaminated. Legionella is in the environment. It can make its way into these water systems. When you think about the size of New York City, if you have one water system that’s not being fully maintained, there’s an opportunity for an outbreak.
On the flip side, think about how many cooling towers, saunas and hot tubs there are. It’s kind of remarkable that we don’t see more of these. Could regulations be tighter? That’s possible. I’m not an expert on water maintenance procedures. Making sure every cooling tower is perfectly maintained is a challenge. There are a lot of human factors involved.
The classic source we hear about is cooling towers, but it can happen anywhere water is aerosolized.
Epicenter NYC: Is there a specific diagnostic test that distinguishes Legionnaires’ disease from the flu or another respiratory illness?
Dr. Handel: Yes. There is a specific test, but it’s not routinely performed unless there’s substantial suspicion. If you walk into urgent care with cough and fever, you’ll often be treated for a typical pneumonia. But if we know you’ve been in an area with a Legionella outbreak, we’re going to test you for Legionella as well.
People with those risk factors may also be tested earlier. The test is readily available and easily ordered in the hospital, but it’s not done on every patient who comes in with pneumonia.
Epicenter NYC: So there isn’t a specific symptom that separates Legionnaires’ disease from other respiratory illnesses early on?
Dr. Handel: That’s correct. If you come into the office and tell a doctor your symptoms, they won’t be able to distinguish Legionella from another respiratory infection based on symptoms alone. That’s one of the challenges in making the diagnosis.
Epicenter NYC: How accurate is the diagnostic test?
Dr. Handel: The test we usually do is a urine test that detects fragments of the Legionella bacteria in someone who has pneumonia. It’s very specific, meaning that if it’s positive, it’s very unlikely to be a false positive. In terms of sensitivity, it detects about 80% of cases.
Epicenter NYC: So if someone doesn’t have symptoms but was exposed, preventive screening isn’t recommended?
Dr. Handel: No. If you don’t have symptoms, we wouldn’t test. Even if you’ve been infected but it’s too early for symptoms, the urine test may still be negative. The tests often aren’t positive until you actually have symptoms.
Epicenter NYC: What is it about Legionnaires’ disease that makes it unable to spread from person to person?
Dr. Handel: It’s an opportunistic infection that affects people who are immunocompromised. It also has to be aerosolized. It’s almost airborne and requires certain-sized droplets. Our lungs generally aren’t producing those airborne droplets that spread it to other people.
Epicenter NYC: What are the biggest misconceptions you hear about where people can and can’t be exposed?
Dr. Handel: People worry about tap water. It’s possible to get it from a shower, but it’s extremely rare. The key is breathing in lots of mist from a contaminated source where the Legionella has had time to grow. Water coming directly through your household pipes usually isn’t sitting there long enough.
Epicenter NYC: What about air filters and dehumidifiers?
Dr. Handel: Those can absolutely be sources as well. Any mist or humidified air you’re breathing should come from equipment that’s properly maintained.
Epicenter NYC: So even equipment inside your home needs to be maintained to prevent the spread of Legionnaires’ disease?
Dr. Handel: Exactly. Large outbreaks happen where many people are exposed, which is why cooling towers are such common sources. But a contaminated machine in someone’s home can absolutely spread Legionella. Personal hot tubs are a classic example, as are personal saunas. Any machine that creates mist or humidified air should be maintained according to the manufacturer’s recommendations.
Epicenter NYC: Is there anything seasonal that makes Legionnaires’ disease more likely in the summer?
Dr. Handel: It does seem to be seasonal. It probably has to do with greater use of cooling towers. People are also spending more time outside, where cooling towers vent air. It’s also warm and moist outside, creating better conditions for that moist air to make its way into our lungs. It’s probably a combination of all those factors.
Very useful information, thanks