A Pediatric Case of Late Relapse of Neonatal Herpes Simplex Encephalitis in a 14-Year-Old

Herpes simplex encephalitis is the most common type of viral encephalitis.However, recurrence or relapse is rare.Late relapse, defined as recurrent active infection later than 3 months from the end of antiviral treatment, is even rarer.The following case illustrates the longest recorded idiopathic late relapse of herpes simplex encephalitis with biopsy-proven confirmation on histopathology.The literature suggests multiple mechanisms for relapse including latent reactivation, post-infectious autoimmune disease, and genetic predisposition.Regardless, untreated recurrent herpes simplex encephalitis has a high morbidity and mortality, and it is the only etiology of viral encephalitis with an effective anti-viral treatment.As such, it should remain an important consideration on the differential diagnosis of encephalitis for prompt recognition and timely management.