Active Surveillance
When a health team proactively goes to a town to gather information about current infectious diseases, this is active surveillance. 1
Definition and Key Characteristics
Active surveillance is defined as deliberate, organized data collection by trained personnel who actively seek out cases and information, rather than waiting for reports to come in voluntarily. 1 This approach is considered the gold standard by major surveillance networks because it provides:
- Unbiased, systematic data collection that enables timely detection of disease patterns and outbreaks 1
- Direct case-finding through organized efforts by health teams going into communities 1
- Reduced underreporting compared to passive systems that rely on voluntary reporting 1
Why This Scenario Represents Active Surveillance
The key distinguishing feature in this question is that the health team went to gather information - this proactive approach is the hallmark of active surveillance. 1 The World Health Organization recommends this method specifically because it allows for proper analysis, feedback, and implementation of control measures. 1
Comparison with Other Surveillance Types
Passive surveillance (Option B) is characterized by waiting for reports to come in voluntarily from treating physicians, with significant risk of bias and underreporting - this is the opposite of what's described in the scenario. 1
Sentinel surveillance (Option C) involves designated reporting sites that monitor specific diseases, but the question doesn't indicate a pre-selected sentinel site system. 1
Syndromic surveillance (Option D) focuses on monitoring symptom patterns and clinical syndromes before laboratory confirmation, typically through automated data systems - not teams gathering information in the field. 1
Clinical Importance
Most diarrheal disease outbreaks are localized events and are often detected by astute clinicians or active surveillance efforts in the community. 2 Active surveillance enables control measures to be implemented promptly and helps identify pathogens and sources of infection to guide appropriate preventive strategies specific to the community at risk. 2