A nurse is caring for an infant in an outpatient pediatrician's office. Exhibits Click to specify if each finding is indicative of fifth disease, measles, or rubella. Each finding may support more than one disease process.

Lymphadenopathy: Generalized lymphadenopathy, or swelling of the lymph nodes, is a common symptom of measles and rubella, but not typically a defining feature of fifth disease. Koplik spots in the mouth: Pathognomonic for measles, appearing as tiny white lesions on the buccal mucosa before the rash. Their presence essentially confirms measles over other viral exanthems. Red rash on the face: Occurs in all three illnesses but with different patterns — measles starts at the hairline and spreads downward, rubella begins on the face and spreads quickly, and fifth disease presents with a “slapped cheek” appearance before spreading. Fever: Common to all three conditions but differs in severity — measles typically produces higher fevers, rubella causes mild fever, and fifth disease may have low-grade fever or none.