In an outbreak, which describes a probable case?

• A. Illness meeting clinical criteria without exposure data
• B. Lab-confirmed infection
• C. Strong clinical evidence with exposure
• D. Not suspected

Answer: (C)

In outbreaks, the designation of a probable case sits between clinical illness and laboratory confirmation by combining two elements: strong clinical evidence of the disease plus an epidemiologic link to the outbreak, such as exposure to a known case or to a suspected source. This pairing makes it highly likely the illness is part of the outbreak, without requiring lab proof yet. Illness that meets clinical criteria but lacks exposure data isn’t as clearly connected to the outbreak, so it wouldn’t be labeled probable. A lab-confirmed infection is more definitive than probable, and not suspected means there’s no basis to think the illness is related to the outbreak.