Surveillance and it's types in epidemiology

Surveillance in Epidemiology:

1. Definition: Surveillance in epidemiology refers to the systematic collection, analysis, interpretation, and dissemination of health-related data to track and monitor the occurrence and spread of diseases in a population. It plays a crucial role in identifying patterns, detecting outbreaks, and facilitating public health interventions.

Types of Surveillance:

1. Passive Surveillance:
  - Definition: Passive surveillance involves the routine reporting of cases to health authorities by healthcare providers or laboratories.
  - Examples: National Notifiable Disease Surveillance System (NNDSS) in the United States, where healthcare providers report cases of certain infectious diseases to local health departments.

2. Active Surveillance:
  - Definition: Active surveillance involves the proactive search for cases by actively reaching out to healthcare providers, laboratories, or individuals in the community.
  - Examples: Influenza-like illness (ILI) surveillance, where healthcare providers and laboratories actively report ILI cases to public health authorities to monitor the prevalence and track the circulating strains, aiding in the development of appropriate vaccines.

3. Syndromic Surveillance:
  - Definition: Syndromic surveillance focuses on monitoring specific symptoms or combinations of symptoms that may be associated with a particular disease outbreak.
  - Examples: BioSense, a program in the United States, which analyzes emergency department visit data for specific syndromes (e.g., respiratory, gastrointestinal) to detect and respond to potential outbreaks in real-time.

4. Sentinel Surveillance:
  - Definition: Sentinel surveillance involves monitoring a subset of key reporting sources within a population known to be representative of the overall population.
  - Examples: Influenza sentinel surveillance, where a network of primary care clinics or hospitals reports the number of patients presenting with influenza-like symptoms, providing a representative sample for estimating influenza activity in the broader population.

5. Laboratory-based Surveillance:
  - Definition: Laboratory-based surveillance relies on the reporting of laboratory test results to identify the presence of specific pathogens or diseases.
  - Examples: National Tuberculosis Laboratory Surveillance System, which collects data on culture-positive cases of tuberculosis in participating laboratories to monitor the trends and identify drug-resistant strains.

6. Event-based Surveillance:
  - Definition: Event-based surveillance involves the monitoring of non-traditional data sources, such as media reports, social media, or electronic health records, to identify and track public health events.
  - Examples: ProMed-mail, an online platform that monitors global infectious disease outbreaks by collecting information from various sources, including news reports and official notifications.

In conclusion, surveillance in epidemiology encompasses various types of systematic data collection and analysis methods to monitor diseases, detect outbreaks, and guide public health interventions. The different types of surveillance mentioned above provide valuable insights into disease patterns, facilitating timely response and control measures.