Acute viral encephalitis in children

2. Viral meningoencepahalitis

Viral meningoencephalitis is an acute inflammatory process involving the meninges and, to a variable degree, brain tissue.


Enteroviruses are the most common cause of viral meningoencephalitis.

Arboviruses are arthropod-borne agents, responsible for some cases of meningoencephalitis during summer months.

Several members of the herpes family of viruses can cause meningoencephalitis. (HSV-1) (HSV-2) (VZV) (CMV) (EBV) (HHV-6).

Other virusesmumps and occasionally by respiratory viruses (adenovirus, influenza virus, parainfluenza virus), rubeola, rubella, or rabies.

Pathogenesis and pathology:

Neurologic damage is caused by direct invasion and destruction of neural tissues by actively multiplying viruses or by a host reaction to viral antigens.

Temporal lobe - HSV
Entire brain – Arbovirus
Basal structures - Rabies

Clinical features:

Fever, nausea and vomiting, photophobia, and pain in the neck, back, and legs are common. The presenting manifestations in older children are headache and hyperesthesia, and in infants, irritability and lethargy. 

Headache is most often frontal or generalized; adolescents frequently complain of retrobulbar pain. As body temperature increases, there may be mental dullness, progressing to stupor in combination with bizarre movements and convulsions. Exanthems often precede or accompany the CNS signs.

The diagnosis of viral encephalitis is usually made on the basis of the clinical presentation of nonspecific prodrome followed by progressive CNS symptoms. The diagnosis is supported by examination of the CSF, which usually shows a mild mononuclear predominance. EEG typically shows diffuse slow-wave activity, usually without focal changes. Neuroimaging studies (CT or MRI) may show swelling of the brain parenchyma. Isolation of the virus from the CSF. PCR for entero and HSV.

With the exception of the use of acyclovir for HSV encephalitis, treatment of viral meningoencephalitis is supportive. Treatment of mild disease may require only symptomatic relief. More severe disease may require hospitalization and intensive care. If cerebral edema or seizures become evident, vigorous treatment should be instituted.


1. Widespread use of effective viral vaccines for polio, measles, mumps, rubella, and varicella.

2. The availability of domestic animal vaccine programs against rabies has reduced the frequency of rabies encephalitis.

3. Control of encephalitis due to arboviruses has been less successful because specific vaccines for the arboviral diseases are not available.

4. Control of insect vectors by suitable spraying methods and eradication of insect breeding sites.

5. Furthermore, minimizing mosquito bites through the application of DEET-containing insect repellents on exposed skin and wearing long-sleeved shirts, long pants, and socks when outdoors, especially at dawn and dusk, reduces the risk of arboviral infection.


about authors

Vasu Burli | DNB (Pediatrics) Fellowship in Pediatric Critical Care

Vasu completed his Pediatrics residency at Kanchi KamaKoti Childs Trust Hospital, Chennai and received further training in Pediatric Intensive care in India and UK