6 Dead, 111 Sickened in New York City Legionnaires’ Disease Outbreak

The outbreak, which started in late July, has been linked to cooling towers on 10 Harlem buildings, officials say.

Legionella pneumophila bacteria in a 1978 electron microscope image. Francis Chandler/CDC via AP

New York City officials said in an Aug. 21 update that six people have died and at least 111 have been sickened in a Legionnaires’ disease outbreak in recent weeks.

Seven people were hospitalized as of Thursday with the disease, a serious form of pneumonia caused by the Legionella bacteria found in water systems, according to the city’s health department.

The outbreak in Harlem started in late July, with the sixth and latest death announced on Thursday by New York City Acting Health Commissioner Dr. Michelle Morse. One person who recently died was confirmed to have had the disease and was associated with the Harlem cluster.

The bacteria that cause Legionnaires’ disease were discovered in 12 cooling towers on 10 buildings, including a city-run hospital and sexual health clinic, health officials said. Remediation efforts have since been completed on all the cooling towers.

“Based on epidemiological evidence, remediation efforts have been effective as new cases continue to decrease,” Morse said in a statement on X.

“The Health Department is continuing our investigation.”

The cooling towers use water and a fan to cool buildings. Officials are investigating a cluster of the disease in the ZIP codes 10027, 10030, 10035, 10037, and 10039.

The department added that the risk of developing the disease in those areas remains low but said people living or working in those ZIP codes who are experiencing influenza-like symptoms should see a health care provider.

“Any cooling towers with initial positive results for Legionella bacteria have completed the treatment required by the Health Department,” the department said. “We are continuing to monitor and let buildings know if additional treatment is needed.”

The Centers for Disease Control and Prevention, in a section about Legionnaires’ disease on its website, says that symptoms include a cough, fever, headaches, aches, and shortness of breath, as well as confusion, nausea, and diarrhea. The symptoms are largely similar to those of other forms of pneumonia.

“Most healthy people exposed to Legionella don’t get sick,” the agency says. “However, certain factors put people at increased risk for developing Legionnaires’ disease.”

The at-risk population includes current or former smokers, people 50 and older, and people with cancer, chronic lung disease, diabetes, kidney failure, or a weakened immune system.

Legionnaires’ disease, if diagnosed early, can be treated effectively, Morse said in a statement earlier in August.

The bacteria can form in freshwater such as lakes or streams, which usually doesn’t pose a risk to people. However, the risk increases when the bacteria form in building water systems.

According to the New York health agency, plumbing systems with favorable conditions for bacteria growth include cooling towers, whirlpool spas, hot tubs, humidifiers, hot water tanks, and evaporative condensers of large air-conditioning systems.

The disease’s name comes from an outbreak in 1976 at an American Legion veterans organization convention at a Philadelphia hotel where more than 180 people became sick and 29 died, according to federal health officials.