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Public health surveillance is the ongoing systematic collection, analysis, and interpretation of data, closely integrated with the timely dissemination of these data to those responsible for preventing and controlling disease and injury.”1 Surveillance activities are usually associated with the study of infectious diseases.

The CDC, WHO, and many other institutions operate databases and automated electronic reporting systems to track and monitor outbreaks of specific diseases, like HIV. The National Notifiable Diseases Surveillance System (NNDSS), a part of the CDC, is an example of such a program. These systems function through the efforts of local and state health departments, working in tandem with a variety of health care providers (laboratories, hospitals, private providers), who are mandated by law to report cases of certain diseases. This allows local, state, and federal health agencies to detect individual cases, control outbreaks, and implement prevention and intervention strategies.2

Data from 57 state, territorial, and local reporting jurisdictions are published weekly and annually in the Morbidity and Mortality Weekly Report (MMWR). Additionally, the National Center for Emerging Zoonotic Infectious Diseases (NCEZID) tracks emerging zoonotic infectious diseases.

Disease registries are another type of public health surveillance. Registries are systems that allow people to collect, store, retrieve, analyze, and disseminate information about people with a specific disease or condition. Disease registries let researchers estimate how large a health problem is, determine the incidence of the disease, study trends over time, and evaluate the effects of certain environmental exposures. Registries provide information to improve the quality and safety of care, and allow for comparison of effective treatment.

Registries are kept by governments, hospitals, universities, non-profits, and private groups. They store data from hospital records, lab reports, and other sources. Because clinical data is sent securely to registries from the various points of care that a patient may receive, registries allow the possibility to track and better understand rare diseases.3

Surveillance data has a higher validity than surveys, because the data comes from lab tests, diagnoses, and other patient records. Registries also make this data easy to store and analyze. The downside to surveillance data is that, because diseases sometimes change definitions, it can be difficult to accurately track trends. Data can also be lacking if hospitals or doctors do not report it.

This diagram shows the steps in a surveillance system, which results in surveillance data.
This diagram shows the steps in a surveillance system, which results in surveillance data.

1 Nsubuga P, White ME, Thacker SB, et al. Public Health Surveillance: A Tool for Targeting and Monitoring Interventions. In: Jamison DT, Breman JG, Measham AR, et al., editors. Disease Control Priorities in Developing Countries. 2nd edition. Washington (DC): World Bank; 2006. Chapter 53.

2 “National Notifiable Diseases Surveillance System (NNDSS)” Centers for Disease Control and Prevention (CDC), 8/19/2015. Web 1/24/2017.

3 American Medical Association (2014) What is a Clinical Data Registry? National Quality Registry Network, 2016


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