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History of Case Definitions

In the United States, requirements for reporting diseases are mandated by state laws or regulations, and the list of reportable diseases in each state differs.  In October 1990, in collaboration with the Council of State and Territorial Epidemiologists (CSTE), CDC published a report entitled Case Definitions for Public Health Surveillance (MMWR 1990;39[No. RR-13]) (the 1990 Report), which, provided uniform criteria for reporting cases.  Download the 1990 Report.

The 1997 updates were published in a report entitled Case Definitions for Infectious Conditions Under Public Health Surveillance (MMWR 1997;46[No. RR-10]) (the 1997 Report). Case definitions for some infectious conditions designated as not nationally notifiable are also included in this report.  Non-nationally notifiable diseases may have been nationally notifiable at some point or may become notifiable at some point. The definitions for non-nationally notifiable diseases are included to facilitate interpretation of data for these diseases, and the diseases that are not notifiable at a national level may be reportable at the state level.  Download the 1997 Report.

The 1990 and 1997 case definitions were developed in collaboration with epidemiologists at CDC and the CSTE.  They were approved by a full vote of the CSTE membership and also endorsed for use by the Association of State and Territorial Public Health Laboratory Directors which is now the Association of Public Health Laboratories (APHL).

For the most current information on procedures for reporting the occurrence of communicable diseases nationally, please email the NNDSS team at  Note that the list of notifiable diseases varies by state, as reporting is mandated only at the state level.