Public Health Surveillance

Definition

• Ongoing systematic collection, analysis, and reporting of health-related data.
• Aims to inform planning, implementation, and evaluation of public health actions and policies.

Key Points

• Primarily focused on infectious disease surveillance, but applicable to:
  • Non-communicable diseases
  • Injuries
  • Health services uptake
  • Environmental hazards
  • Other health issues
• Mechanism to monitor community health.

Uses of Public Health Surveillance

1. Inform Individual Case Management
   • Provides timely treatment and prevents disease spread.
2. Outbreak Recognition and Control
   • Monitor and control infectious disease outbreaks.
3. Detect New Diseases
   • Identify and characterize emerging diseases.
4. Measure Incidence Changes
   • Track changes in disease incidence and risk factors.
5. Evaluate Control Measures
   • Assess effectiveness of public health interventions.
6. Support Research and Policy
   • Inform health policy decisions based on data.

Steps in Public Health Surveillance

1. Identify Objectives
   • Define clear objectives for the surveillance program.
2. Case Definition
   • Establish clinical, epidemiological, and lab criteria for disease classification (possible, probable, confirmed).
3. Data Collection
   • Gather data from clinicians, labs, ports, and other sources.
   • Some diseases require statutory notification to health officials.
4. Data Storage
   • Securely store individual health data due to confidentiality concerns.
5. Data Analysis and Reporting
   • Analyze data and report to stakeholders to inform public health actions.

Types of Surveillance

• Passive Surveillance

  • Ongoing collection of data from notifiable diseases.
  • Low cost, detects trends over time but may suffer from under-reporting.

• Active Surveillance

  • Proactive data collection by contacting clinicians, labs, and the public.
  • Higher quality data, typically used during outbreaks or for high-risk populations.

• Serological Surveillance

  • Testing blood samples for markers (e.g., antibodies) to assess population immunity and plan vaccination programs.

• Sentinel Surveillance

  • Selected healthcare providers report data on specific diseases.
  • Provides insights into disease incidence and affected population characteristics.

• Whole Genome Sequencing Surveillance

  • Analyzes genetic makeup of disease agents to detect changes in infectivity or severity.
  • Example: monitoring variants of COVID-19.

• Syndromic Surveillance

  • Monitors symptoms (e.g., respiratory symptoms, absenteeism) as early warning indicators of community health issues.

Conclusion

• Understanding public health surveillance is essential for effective disease management and policy making.
• Recommended to watch additional resources on epidemiological curves for further learning.