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Case Definitions

A case definition is set of uniform criteria used to define a disease for public health surveillance.  Case definitions enable public health to classify and count cases consistently across reporting jurisdictions, and should not be used by healthcare providers to determine how to meet an individual patient’s health needs.

While the list of reportable conditions varies by state, the Council of State and Territorial Epidemiologists (CSTE) has recommended that state health departments report cases of selected diseases to CDC’s National Notifiable Diseases Surveillance System (NNDSS).  Every year, case definitions are updated using CSTE’s Position Statements.  They provide uniform criteria of nationally notifiable infectious and non-infectious conditions for reporting purposes.

To search for notifiable diseases case definitions by name and by year, use the two search tools on the left side of the NNDSS website.

History of Case Definitions



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