Most common cause of meningoencephalitis in children is: (AIIMS Nov 2014)
1. Enteroviruses cause more than 80% of all cases of meningoencephalitis. Enteroviruses are small RNA-containing viruses; more than 80 serotypes have been identified.
2. The severity of disease ranges from mild, self-limited illness with primarily meningeal involvement to severe encephalitis with death or significant sequelae.
3. Arboviruses are arthropod-borne agents, responsible for some cases of meningoencephalitis during summer months.
4. Several members of the herpes family of viruses can cause meningoencephalitis. Herpes simplex virus type 1 (HSV-1) is an important cause of severe, sporadic encephalitis in children and adults. Brain involvement usually is focal; progression to coma and death occurs in 70% of cases without antiviral therapy.
5. Severe encephalitis with diffuse brain involvement is caused by herpes simplex virus type 2 (HSV-2) in neonates who usually contract the virus from their mothers at delivery.
6. A mild transient form of meningoencephalitis may accompany genital herpes infection in sexually active adolescents; most of these infections are caused by HSV-2. Varicella-zoster virus (VZV) may cause CNS infection in close temporal relationship with chickenpox.
The most common manifestation of CNS involvement is cerebellar ataxia, and the most severe is acute encephalitis.