Many patients experience recurrent herpes labialis yet have no recollection of ever having had primary herpetic gingivostomatitis. What is the MOST likely explanation?

Correct answer: C. The primary infection was subclinical or asymptomatic

• A. Recurrent herpes labialis is caused by HSV-1 in the overwhelming majority of cases.
• B. Recurrence by definition requires prior infection and latency; it is not a new primary exposure.
• C. Correct. The great majority of PRIMARY HSV-1 infections are SUBCLINICAL or so mild that they are never recognised as anything more than a childhood viral illness. The virus nonetheless travels up the sensory axons and establishes LATENCY in the TRIGEMINAL GANGLION. Later reactivation — triggered by ultraviolet light, fever, stress, trauma or immunosuppression — produces recurrent herpes labialis in a patient with no memory of a primary episode.
• D. Most seroconversion occurs in childhood, not adulthood.