Nearly 100 people have been sickened and four have died in a Legionnaires’ disease outbreak in Central Harlem.

The illness, caused by bacteria in contaminated cooling towers, can take up to two weeks to appear and poses the greatest risk to older adults, smokers, and those with weakened immune systems. Most affected towers have been disinfected, but residents and workers in nearby ZIP codes are urged to stay alert for symptoms like fever, cough, and shortness of breath—prompt treatment can save lives.