The city is “aggressively investigating” the outbreak and is testing water from 20 such cooling towers that sit on top of buildings and serve as ventilation for air conditioning systems, Mayor Bill de Blasio said at a news conference.
Results from about half of those buildings returned by Thursday afternoon found water contaminated with the Legionnaires’ bacteria at two sites, a public hospital and a private housing development, he said.
News of the outbreak became public as the city sweltered in a heat wave that has brought with it several days of high humidity and 90-degree temperatures.
Health Commissioner Dr. Mary Bassett said 46 cases of Legionnaires’ disease had been confirmed in the South Bronx since July 10. The two people who died were a woman and a man in their 50s, she said.
Bassett said it was too early in the investigation to say that the contamination in cooling towers at Lincoln Medical Center and the Concourse Plaza housing development were the source of the outbreak. Steps were being taken immediately to decontaminate those towers.
“We move promptly to make sure the towers are being remediated. We don’t wait to show a link between a human case,” Bassett said.
The bacteria that causes Legionnaires’ disease breed in warm water. During hot weather like the city has been experiencing, warm mist from those towers is more likely to be dispersed into the air, the commissioner said.
Bassett and the mayor urged calm and said most people were unlikely to be infected. The commissioner said the elderly, people with lung disease, smokers and people with already compromised immune systems were the most vulnerable.
“We will continue to look at any building we think might be a problem,” the mayor said. “There is no reason for alarm.”
Both officials emphasized that the disease was not spread by human contact and was highly treatable if caught early.
Bassett urged anyone in that part of the city who is experiencing symptoms of the disease — fever, cough, difficulty breathing, headache or muscle pains — to seek medical care immediately.
The cooling tower at Lincoln Medical Center had been flushed out with bleach and fresh water and would be retested before being put back in operation, she said. The tower at Concourse Plaza, a 297-unit affordable housing development on the Grand Concourse, also was being cleaned.
Although some of the Legionnaires’ disease patients were being treated at Lincoln, they came from other areas of the Bronx and no existing patients or staff had contracted the disease, said Ramanathan Raju, president of the city Health and Hospitals Corp., which runs the public hospital system.
Legionnaires’ disease was first identified in 1976 when more than 200 people attending an American Legion convention at a Philadelphia hotel were sickened and 34 of them died.
The national Centers for Disease Control and Prevention estimates that 8,000 to 18,000 people are hospitalized with Legionnaires' disease in the United States each year.