No new deaths have been reported on top of the 10 announced earlier in the week and officials say the outbreak is now on the decline.
To date, 94 people have been admitted to the hospital with the infection since the outbreak began on July 10 in the south Bronx, the poorest section of New York state.
The disease is spread by a bacteria, which has recently been discovered in the cooling towers of five buildings in the South Bronx area.
All those who died were older patients and had pre-existing medical conditions. Legionnaires' disease is not contagious and can be treated with antibiotics.
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"This is literally unchartered territory," New York Mayor Bill de Blasio said yesterday.
"We've never seen an outbreak of Legionnaires like this in the city," he told reporters.
"The good news is, this outbreak is clearly tapering off," he added.
The serious pulmonary infection is spread by bacteria that thrive in warm water, such as that found in hot water pipes, air-conditioning systems and industrial ponds.
Anyone in the Bronx with symptoms such as fever, coughing and shortness of breath are advised to seek medical attention immediately.
De Blasio said 57 buildings with cooling towers were ordered disinfected yesterday and 42 would be inspected and disinfected by today.
The city has set new inspection standards for buildings with cooling and condensing units, and impose penalties for failure to comply.
The disease takes its name from its first outbreak, in 1976, at a Philadelphia hotel where a meeting of the American Legion society was being held.