These three children demonstrate the spectrum of oral infection with herpes simplex virus, which ranges from asymptomatic to severe. (A) The first patient has a single vesicle on his tongue. (B) The second manifests widespread labial lesions. (C) The third patient shows dissemination to the face. In the young child with facial involvement, fluorescein dye is dripping from the left eye after its instillation in an attempt to identify the typical dendritic ulcer seen with herpetic keratitis.