Which surveillance type is defined by actively seeking cases rather than relying on reports?

• A. Syndromic surveillance
• B. Passive surveillance
• C. Active surveillance
• D. Sentinel surveillance

Answer: (C)

Active surveillance focuses on actively seeking out cases rather than waiting for reports to come in. Health authorities proactively search for cases by regularly contacting hospitals and clinics, reviewing records, conducting outreach, and performing field investigations to identify and confirm cases. This approach yields more complete and timely data, which is crucial for outbreak detection and control, though it requires more resources.

In contrast, syndromic surveillance relies on patterns of symptoms or non-diagnostic data (like emergency department chief complaints or over-the-counter drug sales) to flag potential outbreaks. Passive surveillance depends on health care providers to report diagnosed cases to public health authorities, which can lead to underreporting. Sentinel surveillance uses data from selected sites to infer trends about a larger population, rather than capturing all cases.