A new cluster of Legionnaires' disease infections at a public housing complex in the South Bronx has sickened four people over the course of six months, New York City health officials said Wednesday night.

Unlike this summer's outbreak elsewhere in the Bronx that killed at least 12 people and sickened at least 116 others, the flare-up at the Melrose Houses has not been linked to cooling towers, officials said.

Health department investigators are testing the water distribution system in the complex, officials said.

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One building's water has tested positive for Legionella, two have tested negative and the results for five others are still outstanding, officials said. As a precaution, the New York City Housing Authority will shut off hot water at the building that tested positive and install bacteria-eliminating water filters in every apartment unit, health department officials said. Longer-term disinfection plans also are in the works.

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The patients infected by the noncontagious form of pneumonia were not identified, but officials said one person is currently hospitalized and the three others have been treated and released.

The larger South Bronx outbreak -- the source of which was identified as a cooling tower at the Opera House Hotel -- led to an emergency order and legislation to register the city's cooling towers and regulate testing and disinfection.