Differentiate lab-confirmed, clinically compatible, and probable cases in surveillance.

• A. Lab-confirmed: diagnosis based on clinician's impression alone.
• B. Lab-confirmed: disease confirmed by laboratory evidence; Clinically compatible: symptoms plus exposure but no lab confirmation; Probable: strong clinical evidence with some supporting data but not confirmatory lab results.
• C. Clinically compatible: requires lab confirmation.
• D. Probable: is always lab-confirmed.

Answer: (B)

In surveillance, cases are categorized by certainty. Lab-confirmed means the disease is demonstrated by laboratory evidence. Clinically compatible means the person has symptoms consistent with the disease and an exposure history, but there is no lab confirmation. Probable means there is strong clinical evidence with additional supporting data (such as an epidemiologic link or other non-lab information) but no confirmatory lab results. This tiered approach lets public health monitor and respond to cases even when lab results aren’t available yet, while still distinguishing definite laboratory-confirmed cases from those on strong clinical grounds but lacking lab proof. The other statements mix up these distinctions: lab-confirmed isn’t based on clinician impression alone; clinically compatible does not require lab confirmation; and probable isn’t required to be lab-confirmed.