Late relapse of herpes simplex virus encephalitis in a child due to reactivation of latent virus: clinicopathological report and review.

A child suffered from herpes simplex virus encephalitis at the age of 6 months; a late relapse occurred 8.5 years after the initial episode, the longest latency period reported. Radiologic and autopsy findings suggest local reactivation of latent herpes simplex virus as the cause of relapse. All cases of late relapse of herpes simplex virus encephalitis in the last 15 years are reviewed, with emphasis on clinical characteristics and possible mechanisms.