Officials order cooling tower inspections to battle deadly Legionnaires' outbreak in NYC

New York State health officials are ordering widespread inspections of cooling facilities to try to stem New York City’s worst outbreak of Legionnaires’ disease, which had killed 10 people and infected a reported 101 people as of Friday afternoon.

The state and the city are collaborating with the Centers for Disease Control and Prevention (CDC) to suppress the outbreak, Commissioner of Health for New York State, Dr. Howard Zucker, said during a press conference Friday afternoon.

“While it is clearly a significant outbreak in the Bronx, this is a state-wide issue and the governor is monitoring Legionnaires' statewide,” Zucker said.

Beginning Saturday, the state will deploy teams to expedite the process of testing cooling towers and identifying any that may be at risk.

“We want to be confident that every cooling tower in this city is clean," said Dr. Mary Bassett, commissioner of the NYC Department of Health and Mental Hygiene. “The city will be taking a lead for the nation in making sure our cooling towers are safe."

The respiratory disease, which causes pneumonia-like symptoms, isn’t transmitted from person to person but rather by contact with the bacterium Legionella. The bacteria can thrive in warm water and become especially dangerous when the water is turned into a mist that can be inhaled. Medical investigators have linked past outbreaks to public fountains, air conditioning systems, spas, showers and even the misters than keep fruit moist in supermarkets.

City officials confirmed Friday that five towers in the city have tested positive for the bacteria. Investigators are still trying to determine which, if any, of the five cooling towers are directly linked to the illnesses. The presence of the bacteria doesn't necessarily mean the equipment infected anyone.

According to the New York City Department of Health, home air conditioner unites are unaffected, and walking into air-conditioned environments is safe.

City officials said Friday that they had received the lowest number of new cases in 24 hours and are observing a  downturn in the outbreak, which was a reflection of their effort to identify at-risk towers.

Bassett said during the press conference that she would “retain the confidence I have in the past that we have a good handle on the outbreak in the Bronx.”

On Thursday, the New York City Health Commissioner issued an order to all building owners with cooling towers to disinfect the towers within 14 days of receiving the email.

"Everyone understands that the outbreak has been limited to one community in our city," NYC Mayor Bill de Blasio said in a press conference Thursday. "We’re doing this out of an abundance of caution."

It is unclear exactly how many cooling towers there are in the city, but Bassett said Thursday that there are at least 2,500, mostly in commercial and industrial settings.

The Centers for Disease Control and Prevention (CDC) estimates that between 8,000 and 18,000 people in the United States are hospitalized with Legionnaires' disease every year, but the actual number may be higher due to underreporting. More illnesses usually occur in the summer and early fall.

Previous outbreaks of the disease in the U.S. include a 1994 cluster aboard a cruise ship between New York and Bermuda— due to whirlpool baths— as well as the largest outside of the U.S., in 1985 in England, when 22 people died after contracting the disease at a hospital. In 2010, contaminated water in a waterfall of a Wisconsin hospital lobby was believed to be responsible for sickening eight people.

Dr. Stephen Morse, an epidemiology professor at Columbia University's Mailman School of Public Health, described the current Legionnaires' outbreak as a "wake-up call" and likened it to outbreaks of food-borne illnesses like salmonella.

"These are unusual events. However, they are indicative of a broader problem," Morse told "In restaurants, employees are supposed to wash their hands and there are appropriate rules for that. It shouldn’t take an outbreak of salmonella or some other food-borne disease to show that the food should be properly cooked or properly stored or that people aren’t washing their hands properly."

"This kind of thing probably could be prevented," he said of the current Legionnaires' outbreak in the Bronx.

According to a study published in the September-October 2014 issue of the Journal of Public Health Management and Practice, reported cases of legionellosis more than tripled between 2001 and 2012 in the United States. In the study, researchers advise that federal, state and local officials make legionellosis diseases a higher public health priority.

“This is a very underreported disease nationwide,” Dr. Claressa Lucas, of the National Center for Immunization and Respiratory Disease, said during the press conference Friday. “I think a situation like this, where we have explosive outbreaks, do serve to educate the public.”

The Associated Press and Reuters contributed to this report.