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.

An outbreak of Legionnaires’ disease in New York City’s Central Harlem neighborhood has now caused three deaths, and health officials are still trying to track down the source.