Provide an example of how syndromic surveillance might provide an early signal of an outbreak.

• A. A sudden rise in emergency department visits with fever and cough in a region may indicate an influenza outbreak before lab confirmations.
• B. A sudden drop in ED visits across all age groups.
• C. Consistent number of ED visits with no symptoms changing.
• D. Data shows only non-ill visits.

Answer: (A)

Syndromic surveillance detects outbreaks by watching for unusual patterns in symptoms and care-seeking behavior in near real time, rather than waiting for lab-confirmed diagnoses. An early signal example is a sudden rise in emergency department visits with fever and cough in a region. This clustering of respiratory symptoms can point to a possible influenza outbreak before lab tests confirm it, giving public health officials time to investigate, broaden testing, and implement timely responses.

The other scenarios don’t fit as early signal indicators: a sudden drop in ED visits isn’t consistent with a growing outbreak; a stable number with no change provides no hint of a new cluster; and data showing only non-ill visits wouldn’t reflect an illness signal at all.