Active Surveillance
This is active surveillance because the health team is proactively visiting hospitals and laboratories to seek out and gather information about influenza cases, rather than waiting for reports to come to them. 1
Key Distinguishing Features
Active surveillance involves deliberate, organized data collection by trained personnel who actively seek out cases and information, which is exactly what this health team is doing by going out weekly to visit facilities. 1 This approach is recommended by the World Health Organization as the gold standard because it provides unbiased, systematic data collection that enables timely detection of disease patterns and outbreaks. 1
Why This Is NOT the Other Options
Not Passive Surveillance
- Passive surveillance relies on healthcare providers initiating reports as part of their routine practice, where the surveillance system waits for reports to come in voluntarily. 2, 1
- The CDC's influenza surveillance system is an example of passive surveillance, where data flows from healthcare facilities to state health departments through established reporting channels without active case-finding. 2
- Passive surveillance is characterized by significant risk of bias and underreporting because it depends on voluntary reporting. 1
Not Sentinel Surveillance
- Sentinel surveillance involves selected reporting sites or populations to monitor disease trends, not comprehensive case gathering from all hospitals and healthcare facilities in a town. 2
- The scenario describes visiting multiple hospitals and laboratories throughout the town, which is broader than the targeted approach of sentinel surveillance. 2
Not Syndromic Surveillance
- Syndromic surveillance monitors symptom patterns or clinical syndromes (like influenza-like illness) before laboratory confirmation, typically through automated data systems. 2, 1
- The scenario describes gathering information about actual influenza cases, not just monitoring symptom patterns. 2
Clinical Advantages of This Approach
Active surveillance systems like the one described can detect cases 7 to 8 weeks earlier than passive electronic disease reporting systems, making them valuable as early warning systems for identifying initial entry points of different influenza strains into the community. 3
Answer: A - Active