https://en.m.wikipedia.org/wiki/1976_Philadelphia_Legionnaires%27_disease_outbreak https://en.m.wikipedia.org/wiki/1976_Philadelphia_Legionnair... 1976 new ill

https://en.m.wikipedia.org/wiki/1976_Philadelphia_Legionnaires%27_disease_outbreak https://en.m.wikipedia.org/wiki/1976_Philadelphia_Legionnair... 1976 new illness appeared, CDC did a full investigation, identified the cause.