Mayor Bill de Blasio said Thursday that the deadly Legionnaires outbreak in the Bronx is contained while lawmakers passed a new set of regulations to inspect cooling towers.

"We've been saying very consistently this has been contained and we have no new cases," de Blasio said.

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Health Commissioner Dr. Mary Bassett explained that the city cannot assume that New Yorkers are totally out of the woods given the bacteria's incubation period of up to 10 days.

"We do not expect the case count to go down to zero," Bassett warned, explaining that the city always expects a normal rate of Legionnaires infections even as clusters of newly infected New Yorkers shrink.

As of Thursday afternoon, officials said the number of infected patients remained at 121 reported cases, with no new cases since Aug. 3. Twelve people have died from the pneumonia-causing bacteria.

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However, recent testing of cooling towers in the South Bronx area thought to be the epicenter for the outbreak continue to test positive.

The mayor said 38 buildings with cooling towers in the borough's affected area have been cleaned and decontaminated. 

De Blasio also said he expected to sign off on a bill passed unanimously by the City Council Thursday afternoon.

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The law, which would require all cooling towers to be registered with the city and inspected every three months, is expected to go into effect immediately after de Blasio signs the bill.

Building owners will have 30 days to register existing cooling towers with the Department of Buildings. Violations that lead to injury or death can earn up to a $10,000 penalty. 

Despite political bluster from de Blasio's critics on the city's response to the outbreak, Dr. Matthew Moore of the Centers for Disease Control and Prevention praised City Hall's response to the health scare, describing it as "swift, diligent and robust."