Who met a case definition and reached the reporting system?
Useful for tracking patterns using standardized criteria. Not every diagnosed infection is reported, and surveillance definitions are not clinical rules for an individual patient.
Use the right number
Reported cases and estimated diagnoses answer different questions.
Surveillance counts are built for consistent public-health monitoring. Estimates try to describe the larger burden that routine reporting does not capture.
How many people may be diagnosed in routine care?
CDC research using insurance claims estimated a much larger annual number of diagnoses than the national surveillance count. Estimates depend on their data and methods; they are not county case totals.
Practical takeaway
Do not multiply or “correct” a county on this map.
There is no defensible universal multiplier for turning one county’s reported count into its true number of infections. Use the map for surveillance context and a clinician for personal medical questions.
CDC Emerging Infectious Diseases estimate study ↗