The death toll from an outbreak of Legionnaires' disease in New York grew to seven as investigators identified and disinfected five air-conditioning cooling towers in the South Bronx that tested positive for the bacteria that causes the disease.

New Yorkers have been on high alert since July 10 when the outbreak was first identified and have been flooding doctors offices and hospitals with symptoms of fever, cough, chills, muscle aches and other signs of the disease. A type of severe pneumonia, Legionnaires' disease -- which was named after an outbreak during a 1976 meeting of the American Legion in Philadelphia -- is not spread from person to person but by breathing in mist with the organisms. Outbreaks usually occur in the summer.

In New York this year, 86 people have been confirmed to have been infected with the disease as of Tuesday. The cluster is large enough to worry public health officials but it's not quite a crisis. An estimated 8,000 to 18,000 people are hospitalized each year in the country due to Legionnaires' disease.

[Legionnaires’ disease, once ‘the greatest epidemiological puzzle of the century,’ kills seven in N.Y.]

Officials said they didn't how how the water in the towers became infected in the first place but scrubbed them by hand with bleach and other chemicals.

Jay Varma, deputy commissioner for disease control, told NBC News that authorities hoped the disinfection of the contaminated cooling towers would be enough to stop the outbreak.

"We hope that there are no more cases, and certainly hope no more deaths, but do expect additional cases simply because there could be people who may have been infected before the cooling towers were cleaned," Varma said.

[CDC: We could cut future superbug infections in half]

New York City Mayor Bill de Blasio on Monday called for a more "systemic solution" to stop the cycle of outbreaks and said new legislation would be announced next week to fight the disease. He said the solution will include inspections, new recommended actions in case of positive tests, and sanctions for those who do not comply with new standards.

"Legionnaires’ Disease outbreaks have become far too common over the past ten years," de Blasio said in a statement released by his office, "and the City will respond not by only addressing an outbreak as it occurs, but with a new plan to help prevent these outbreaks from happening in the first place.”

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