UNDATED-AP- A Legionnaires’ disease cluster in New York City has sickened more than 20 people in two Upper East Side neighborhoods. The disease is a type of pneumonia caused by Legionella bacteria. They grow in warm water and can spread in building water systems such as showerheads, hot tubs and c ooling towers. People can get it from breathing in tiny droplets of contaminated water. Symptoms usually develop two days to two weeks after exposure and include cough, fever, headaches, muscle aches and shortness of breath. Legionnaires’ disease can be treated with antibiotics. If untreated, people can suffer complications and even die. ...read more read less