Active surveillance is characterized by:

• A. Periodic solicitation; more accurate but costly
• B. Relies on voluntary reporting by clinicians
• C. Uses sentinel sites only
• D. Is a passive system

Answer: (A)

Active surveillance means the public health team actively seeks information rather than waiting for reports to come in on their own. This usually involves periodically soliciting reports from clinicians, laboratories, hospitals, and other sources, and often includes follow-up to confirm cases. Because reporting is prompted and data are verified, the information tends to be more complete and accurate, but it requires more resources and higher cost to maintain.

Relating to the other ideas: relying on voluntary reporting describes passive surveillance, where you wait for reports to arrive. Using sentinel sites only is too restrictive a setup and isn’t the defining feature of active surveillance. And calling it a passive system would be incorrect.