National Notifiable Diseases Surveillance System
The National Notifiable Diseases Surveillance System (NNDSS) provides weekly provisional information on the occurrence of diseases defined as notifiable by the Council of State and Territorial Epidemiologists.
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 CDC annually review the status of national infectious disease surveillance and recommend additions or deletions to the list of nationally notifiable diseases 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 notifiable varies slightly by state. State epidemiologists report cases of notifiable diseases to CDC, which tabulates and publishes these data in Morbidity and Mortality Weekly Report (MMWR) and in Summary of Notifiable Diseases, United States.
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 of data reporting is also influenced by the diagnostic facilities 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.
National Center for Health Statistics. Health United States 2009: With Special Feature on Medical Technology. Hyattsville, Maryland. 2010; pp 469-470.