Health officials say they are confident that the outbreak of Legionnaire's disease in New York City is now over.

The announcement was made during a press conference at the New York City Health Laboratory on Thursday, ABC 7 reporterd.

Commissioner Dr. Mary Bassett identified the Bronx Opera House Hotel's water-cooling tower as the original source of the bacterial disease that had killed a total of 12 people in that area since July 10.

She said tests from three different labs confirmed that 25 samples from people who contracted the disease were linked to the genetic code of the Legionella bacteria found at the hotel's tower.

Legionella bacteria has been found in 14 water towers in the area. All 124 cases of the disease were clustered in the South Bronx.

The City Council passed legislation on Thursday requiring regular testing of water-cooling towers across the city.

"We intend to go beyond the requirement to test our cooling tower every 90 days by testing every 30 days when the tower is in operation," a spokesperson for the hotel said.

What is Legionnaire's Disease?

The disease, a form of bacterial pneumonia, was first discovered after an outbreak at an American Legion convention in Philadelphia in 1976 when many people became sick with respiratory illness.

The disease cannot be passed from person to person and is spread chiefly by a person breathing in small droplets of contaminated water, according to the CDC.

Legionella bacteria can multiply quickly in artificial water supply systems like air conditioning systems. Large buildings are more vulnerable to contamination because of their complex water supply systems.

Legionella bacteria thrives in warm water and become especially dangerous when the water is turned into a mist that can be inhaled. In the case of New York City's outbreak, the infected people may have simply been walking by on the street when they inhaled mist that appears to have come from the cooling towers.

Additional reporting by Megan Specia