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.

New York City health officials are continuing to investigate a cluster of Legionnaires’ disease, a serious bacterial lung infection, where the number of cases has risen to 73, including three deaths.

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.