Which surveillance type relies on reports by providers without the agency directly requesting data?

• A. Passive Surveillance
• B. Active Surveillance
• C. Registries
• D. Sentinel Surveillance

Answer: (A)

The main idea here is reporting behavior: passive surveillance relies on health-care providers and laboratories to report cases to public health authorities without the agency having to go out and request the data. This means data flow comes from routine reports that providers submit as part of their normal practice or because it’s legally required, not because the agency actively sought them.

This fits the description because the agency isn’t directly asking for each case; instead, it waits for providers to report what they see. In contrast, active surveillance has the agency actively contacting sources to obtain information. Registries collect data in a structured system for particular diseases or exposures, but they aren’t defined by unsolicited provider reports alone. Sentinel surveillance uses a selected network of reporting sites to monitor trends, which is a proactive, site-based approach rather than broad unsolicited reporting.