Public health surveillance is defined as:

• A. A random survey of hospital patients
• B. Systematic collection, analysis, interpretation, and dissemination of health data to guide actions
• C. A one-time data collection project
• D. Surveillance is only about infectious diseases

Answer: (B)

Public health surveillance is the ongoing, systematic collection, analysis, interpretation, and dissemination of health data to guide actions that protect and improve population health. It isn’t just a one-time study or a single survey; it continuously gathers and analyzes information from various sources to identify trends and outbreaks and to inform decisions, policies, and interventions. The data should be shared with those who can act on it, from frontline public health workers to policymakers.

This approach applies to a wide range of health issues, not only infectious diseases. It includes tracking chronic conditions, risk factors, environmental exposures, and health service utilization to guide program planning and resource allocation. The other options don’t fit because they describe isolated or narrow activities (a random survey of hospital patients), a one-time data collection, or a view of surveillance limited to infectious diseases.