National Notifiable Diseases Surveillance System (NNDSS)

Years Available
1912 to present
Mode of Collection
Abstraction of records for all case reports of notifiable diseases received by participating state and territorial health departments.
The National Notifiable Disease Surveillance System (NNDSS) is a nationwide collaboration that enables all levels of public health (local, state, territorial, federal, and international) to share health information to monitor, control, and prevent the occurrence and spread of state-reportable and nationally notifiable infectious and some noninfectious diseases and conditions. NNDSS is a multifaceted program that includes the surveillance system for collection, analysis, and sharing of health data, resources, and information about policies and standards at the local, state, and national levels. NNDSS provides weekly provisional and annual finalized information on the occurrence of diseases defined as notifiable by the Council of State and Territorial Epidemiologists (CSTE). Data include cases of nationally notifiable conditions, which are reported using uniform surveillance case definitions.
Selected Content
Data include cases of nationally notifiable conditions using uniform case definitions.
Population Covered
Notifiable disease reports are received from health departments in the 50 states, the District of Columbia, New York City, and 5 territories (American Samoa, Guam, Northern Mariana Islands, Puerto Rico, U.S. Virgin Islands).
Notifiable disease surveillance is conducted by public health practitioners at local, state, and national levels to support disease prevention and control activities. The Council of State and Territorial Epidemiologists and The Centers for Disease Control and Prevention (CDC) annually review the status of national disease surveillance and recommend additions or deletions to the list of nationally notifiable conditions based on the need to respond to emerging priorities. Because reporting is currently mandated by law or regulation only at the local and state levels, the list of diseases that are considered reportable varies slightly by jurisdiction. The case reports CDC receives reflect this jurisdiction-level variation. CDC publishes weekly electronic tables and reports of notifiable disease data through the CDC WONDER system and on
Interpretation Issues
NNDSS data must be interpreted in light of reporting practices. If persons who have a reportable disease do not seek medical care from a health care provider, the case may not be reported. The degree of completeness and timeliness of data reporting is also influenced by the diagnostic facilities and tests available, the control measures in effect, public awareness of a specific disease, and the interests, resources, and priorities of state and local public health officials. Finally, factors such as changes in case definitions for surveillance, introduction of new diagnostic tests, or discovery of new disease entities can cause changes in disease reporting that are independent of the true incidence of disease.