In early July, the Upper East Side saw a cluster of Legionnaires’ cases. Then the Guggenheim and the Met tested positive for Legionella, which is the bacteria that causes the disease if inhaled. Late last week, it was the Ardsley, a prewar, white-glove co-op on the Upper West Side, that became the Legionnaires’ locale of note. All told, as of Tuesday, water in the cooling towers of 76 buildings across the city had tested positive for Legionella. According to the city Health Department, 63 people have been hospitalized, though 40 have already been discharged. And thankfully, there have been no deaths reported so far.
If this sounds familiar, it’s because the same thing happened around this time last year. So how worried should you be about the semi-seasonality of a disease that has a 10 percent fatality rate? Is it safe to shower right now? Can you walk past the Ardsley without a hazmat suit? Should everyone on the Upper East Side just decamp to the Hamptons while this gets worked out? We talked to Dr. Wafaa El-Sadr, an epidemiologist at Columbia University’s Mailman School of Public Health, about how a reasonable New Yorker can best navigate what’s starting to feel like Legionella season.
Why did this outbreak even happen?
In a place like New York City, Legionella really spreads through the mist or the vapor that’s generated by cooling towers that are often found on the top of large buildings. These cooling towers are a good medium for these bacteria, which look like rods, to multiply and grow. Once you have enough of them, they’re distributed in the vapor and mist that comes out of these cooling towers and then that comes down and settles on the sidewalks or in the air where people are walking.
Can you catch it from someone who’s come into contact with the bacteria?
It’s spread by actually breathing in this mist; it is not passed from person to person.
And if you have it, how freaked out should you be?
Most people who are exposed to this infection do not develop symptoms. Those include aches and pains, fever, cough, shortness of breath. But older individuals, smokers, people with chronic conditions like chronic lung disease, chronic kidney disease, heart disease, are particularly vulnerable.
What happens if you live or work in one of the buildings that have tested positive for Legionella, like the Met?
When testing shows there’s evidence of these organisms in cooling towers, it’s necessary to drain the water, dry them out, then treat them to make sure that you eliminate any evidence of this germ. Then you’re good to go. But it doesn’t mean that you stop monitoring because inevitably it may happen again. That’s why in New York City, there are rules and regulations and guidelines regarding frequent sampling and testing at these cooling towers.
So it’s not something that comes in through tap water, for example.
This organism is not in the plumbing, at least with the Upper East Side cluster. It’s not spread by drinking the water. It’s not spread by taking showers, by using the water to cook, or anything like this. There’s no reason to leave the building or to go elsewhere.
Are there precautions a person can take?
If you’re going in and out of the building and just being super-careful, you might want to wear a mask, for example, because that’s where the mist would be settling down from the cooling tower.
Should I avoid walking along Museum Mile?
For the majority of people, they should not be concerned. If a person does have one of these conditions that make them particularly vulnerable to Legionnaires’, I think it might behoove them to avoid the block, or if they have to walk in that area, maybe they should wear a mask. But it’s only for people who are particularly vulnerable to Legionnaires’ disease.
How does the city determine the cause of an outbreak?
There are rapid tests that can be done that can identify that the organism is in the water, which can include both live and dead Legionella. Then there are more sophisticated tests that can be done further to check whether the germ you got from this cooling tower is the same one that you recover from the patient. Those take a longer time to be able to genetically link the source with the cases of Legionnaires’.
The current cluster is on the Upper East Side, but on the west side, the Ardsley’s hot-water system tested positive for Legionella, too. Did the bacteria somehow spread all the way across Central Park?
It’s unlikely that it’s an organism from a cooling tower on the East side migrated to the West side.
So it’s possible that the people at the Ardsley just checked their own system after seeing cases elsewhere in the city. Which is, I guess, a good thing. As more cases emerge, is it possible that more buildings will be more proactive and forthcoming about their testing?
When you identify something like this, then people afterward become hyper-vigilant. Maybe they’re looking at their data, they’re testing more regularly, and very importantly, they’re also disclosing it. Maybe a year or two ago, the management of a building may not have felt compelled to let the residents know. But I think now it’s a good sign that there’s more willingness to share public-health issues with the public.
Can the city do more to get ahead of this? It feels like a seasonal occurrence now.
There is guidance already on the frequency of testing the water. The city should be vigilant in terms of making sure the management companies that manage these buildings are doing this on a regular basis, they’re disclosing this when they have a positive test, and they move ahead and do the mitigation right away. At the same time, I think the city is also doing a good job at disseminating information about Legionnaires’ — what it is and what it isn’t, how you get it and how you don’t get it.
Is climate change somehow to blame here?
I don’t think we’ve proven it definitively, but certainly, as with more hot days and more extreme heat, that change has a huge impact on environmental consequences. And it means we may have heavier, faster growth of organisms like Legionella.
