A Legionnaires' disease cluster in the Harlem area of New York City has caused three deaths and over 70 people to be sickened. Here's what it is, symptoms and how it's spread.

Three people have died and at least 67 people have been diagnosed with Legionnaires’ disease in a cluster that broke out in New York City last week.

Fifty-eight people in New York City have been diagnosed with Legionnaires’ disease, a serious bacterial lung infection, and two people have died, according to the city health department.