The US Centers for Disease Control and Prevention says it has closed several buildings it leases in Atlanta because Legionella bacteria have been found in their water systems -- bacteria that likely grew because of the prolonged pandemic shutdown.
It's a problem that people across the country need to be on the lookout for, the CDC says. The bacteria, which can cause deadly pneumonia, grow in warm or stagnant water.
The plumbing in buildings that have been closed for months because of the coronavirus pandemic could provide a perfect breeding ground for Legionella and other waterborne pathogens, the CDC cautions.
It even happened to the CDC itself.
"During the recent closures at our leased space in Atlanta, working through the General Services Administration (GSA), CDC directed the landlord to take protective actions," the CDC said in a statement to CNN.
"Despite their best efforts, CDC has been notified that Legionella, which can cause Legionnaires' Disease, is present in a cooling tower as well as in some water sources in the buildings. Out of an abundance of caution, we have closed these buildings until successful remediation is complete."
Legionella bacteria are common in water everywhere. They're usually only a problem when the water gets aerosolized and people breathe it in. Showers and fountains are common sources. The name dates back to 1976, when an outbreak among people at an American Legion convention in Philadelphia affected 182 people and killed 29 of them.
People most at risk include the elderly, smokers, people with suppressed immune systems and diabetics.
Last year, the CDC reports, 4,294 cases were reported. So far this year, 1,813 cases have been reported.
It's not yet clear if the pandemic has worsened the problem, or perhaps eased it because people are not gathering at large hotels or working in big factory buildings as much, said Chris Edens, an epidemiologist on CDC's Legionella team. He said state health departments that normally monitor and report cases of Legionella infection are tied up dealing with coronavirus.
And no national entity systematically checks buildings to see if the bacteria has started growing in the plumbing. "There is currently no nationwide surveillance of water systems for Legionella disease," Edens said.
As people return to work and start to travel more, hospitals and clinics need to think about the possibility of Legionella, Edens said. "Flu and coronavirus are not the only things that can cause severe pneumonia," he said. If people turn up with pneumonia, it's worth testing them for Legionella -- especially since it can be treated with antibiotics, unlike flu or coronavirus.
Many different buildings could be at risk, and building managers need to be aware during prolonged closures. "We are talking hotels, we are talking large office buildings, we are even talking certain kinds of factories ... a lot of those buildings have been shut down," Edens told CNN.
"This water has been sitting and could be at risk of Legionella growth."
Poorly maintained cooling towers are another potential source.
The fix is not difficult. "You want to keep the cold water cold and you want to keep your hot water hot," Edens said. Legionella flourishes at temperatures between 80° and 120° Fahrenheit. It's killed by chlorination and other disinfecting routines, but the bacteria can grow into mats that create hard-to-dislodge sludge inside pipes, Edens said.
"One of the things that we typically recommend in buildings that have been disused is flushing," he said.
"That can be as simple as turning the faucet on. Let cold or hot water course through the system. Keep that water moving."
Legionella is not the only risk, by the way. "There's lots of different waterborne pathogens," Edens said. "There are certainly other bugs out there."
The CDC warns about them on its website.
"These can include other microbial hazards, such as non-tuberculous mycobacteria, changes in water chemistry that lead to corrosion, leaching of metals (such as lead) into stagnant water, disinfection by-products, and sewer gases that enter buildings through dry sanitary sewer drain traps," it says.