City health officials sampled 24 cooling towers while investigating the cluster. Ten produced positive PCR results, including the tower at Yankee Stadium at 1 E. 161st St. PCR testing can detect genetic material from Legionella bacteria. However, it cannot determine whether the bacteria are alive. Only live Legionella bacteria can cause illness, and additional laboratory culture testing is underway to help determine whether viable bacteria were present in the sampled towers.
