herpes simplex meningo-encephalitis

Last reviewed 01/2018

Herpes simplex infection is a relatively common cause of meningo-encephalitis. This condition is frequently severe - it causes an acute necrotising encephalitis - and has a high mortality.

NICE suggest that, in a child less than 5 years, one should consider possible herpes simplex encephalitis if:

  • focal neurological signs
  • focal seizures
  • decreased level of consciousness

The condition may occur during the primary infection or as the result of activation of the virus lying dormant due to a previous infection. It may develop in apparently well children without skin lesions.

The outcome of this disease depends on early diagnosis and treatment. Acyclovir is administered empirically and attempts to establish the diagnosis made by examination of the cerebrospinal fluid after two weeks.


  1. NICE (May 2007). Feverish illness in children Assessment and initial management in children younger than 5 years