120 diseases or conditions health departments voluntarily report to CDC. State, local, and territorial public health departments verify and report cases to CDC.
When there are differences between numbers of cases reported by CDC versus by health departments, data reported by health departments should be considered the most up to date.
Health departments may update case data over time when they receive more complete and accurate information. The number of new cases reported each day fluctuates.
There is generally less reporting on the weekends and holidays.CDC reports death data on three sections of the website: U.S.