NEW YORK (CBSNewYork) — Three more buildings in the Melrose Houses in the Bronx have preliminarily tested positive for legionella bacteria, following a cluster of Legionnaires’ disease cases in the public housing development.

The buildings will now all have their hot water shut off until the Department of Health and Mental Hygiene can install copper-silver ionizers to eliminate the bacteria.

The buildings that have now registered preliminary positives are located at 304 E. 156th St., 346 E. 156th St., and 320 E. 156th St.

Another building, at 681 Courtlandt Ave., already had its hot water turned off after a preliminary positive test, and filters were distributed to every apartment. Hot water has since been turned back on in the Courtlandt Avenue building.

Over the last six months, four residents of the Melrose Houses have come down with Legionnaires’ Disease. The most recent patient was diagnosed last week. Another case was diagnosed earlier in the year, and two others were diagnosed during the South Bronx Legionnaires’ epidemic earlier in the summer.

A Legionnaires’ outbreak earlier in the summer killed a dozen and sickened over 100 more in the South Bronx, prompting city guidelines for testing and treating cooling towers. The epidemic was traced to a cooling tower at the Opera House Hotel.

The Melrose Houses case differs from earlier cases in that instead of the source originating from cooling towers, the bacteria was detected in the drinking water system – though only in the hot water, 1010 WINS’ Al Jones reported.