A Legionnaires' disease cluster in the Harlem area of New York City has caused three deaths and 5over 60 people to be sickened. Here's what it is, symptoms and how it's spread.

An outbreak of Legionnaires' disease in New York City has killed three people and sickened more than five dozen since late July.

Nearly 60 people have become sick and two have died in an outbreak of Legionnaires' disease in New York City. Health officials there issued an alert on July 30 warning residents of Central Harlem who have flu-like symptoms to see a health care provider immediately.