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.

The cases are most likely linked to a cooling tower in central Harlem, health officials said. At least 58 people have fallen ill, including two people who have died, from Legionnaires’ disease in New York City over the past several weeks, according to the city’s health department.