Herpes simplex serious neurological disease in young children: incidence and long-term outcome

Objective To determine the contribution of herpes simplex virus (HSV) to serious neurological disease. Setting and patients A 3-year prospective survey of children aged 2–23 months in Britain and Ireland. Results 19 children had HSV central nervous system (CNS) infection; 13 aged 2–11 months had focal neuroimaging abnormalities and 11 long-term neurological sequelae. Of six aged 12–35 months, one had abnormal neuroimaging and three long-term neurological sequelae. 17 of the 19 had serious neurological disease. HSV CNS infection accounted for 23% of serious neurological disease in children aged 2–11 months and 4.5% in older children. Conclusions The incidence of HSV-induced serious neurological disease in the UK was estimated at 1 in 64 000/year in younger children and 1 in 230 000 in older children. HSV CNS infection has clinical effects ranging from frank encephalitis to severe illness with fever and convulsions to milder disease lacking encephalopathy.