Legionnaires’ disease is a severe form of bacterial pneumonia and an outbreak is occurring in New York City’s Harlem area.

When it comes to Legionnaires' disease, this doctor explains how buildings can prevent it and what symptoms to watch for an early diagnosis.

A t least three people have died in a Legionnaires’ disease outbreak in Harlem, authorities said in the most recent update, in the latest summer flare-up of the disease that officials say primarily impacts older people and is potentially linked to poorly maintained cooling towers.