Central nervous system infection of Herpes simplex virus (HSV) is the most common etiologic agent of the non-epidemic fatal form of
encephalitis. Relapse of HSV
encephalitis is rare in childhood. In this report, we present our experience in a 36-month-old child with relapse of HSV
encephalitis after 14-day
acyclovir therapy. A 36-month-old boy who was presented with deterioration in speech and motor functions and fluctuation of consciousness was treated with
acyclovir for 14 days for HSV
encephalitis. He was discharged since his cerebrospinal fluid findings returned to normal range and clinical improvement was seen. Ten days later, he was readmitted to our clinic with acute
fever, focal convulsions and choreoathetoid movements, and altered consciousness.
Acyclovir was started immediately, but he died on the 17th day because of
respiratory failure. Relapses due to HSV
encephalitis are rare and limited to a small number of case reports in the literature. Persistence of HSV, detection of high viral load or detection of HSV by polymerase chain reaction, prior
corticosteroid therapy, low total dosage of
acyclovir (especially for children under 2 years of age) and short
duration of therapy were suspected risk factors. Even absence of
pleocytosis and normal cerebrospinal fluid biochemistry in our patient
after treatment did not indicate eradication of HSV. In our opinion,
treatment duration of HSV
encephalitis, especially in small children, must be at least 21 days. Clinical and experimental studies are required since only case reports on this topic exist.