Which statement best describes the difference between active and passive surveillance?

• A. Active surveillance requires the agency to actively seek out information; passive surveillance relies on reports provided by providers without being prompted.
• B. Active surveillance relies on reports provided by providers; passive surveillance requires direct outreach by the agency.
• C. Active surveillance is faster in all cases; passive surveillance is slower in all cases.
• D. Active surveillance never uses registries; passive surveillance always uses registries.

Answer: (A)

Understanding the difference hinges on who is doing the data gathering. Active surveillance means public health officials take the initiative to seek out information about cases—they reach out to hospitals and labs, review records, conduct interviews, and do targeted case finding, especially during outbreaks or for high-priority diseases. Passive surveillance relies on information flowing in from providers and laboratories without the agency actively looking for it—through routine reporting forms and notifiable-disease reports that are submitted on their own initiative.

This makes the statement that best describes the difference the one that says active surveillance requires the agency to actively seek out information, while passive surveillance depends on reports provided by providers without prompting. The other ideas don’t fit as well: swapping who does outreach is inaccurate, claiming active surveillance is always faster ignores that speed depends on context and systems, and saying registries are never or always used misrepresents how registries can be part of either approach.