14th June 2023

Viral meningitis

In the UK, viral meningitis is the most common form of meningitis. Enteroviruses account for the majority, followed by herpes simplex and varicella zoster. It remains the most common cause of aseptic meningitis (i.e. no cause found after routine CSF stains and cultures). However, aseptic meningitis can also be caused by partially treated bacterial infections, fungi, parasites, drugs, and systemic disease, e.g. SLE, sarcoidosis, and Bechet’s disease.

Clinical features include acute onset meningism (i.e. neck stiffness, headache, photophobia) and fever. CSF shows a pleocytosis that is predominantly lymphocytic.

Aetiology

Herpes simplex virus (HSV-1) tends to cause encephalitis, whilst HSV-2 commonly causes meningitis. Mollaret syndrome is frequently associated with HSV-2, which is a recurrent and benign aseptic, lymphocytic meningitis.

Enterovirus infection can be suggested by a history of contact with small children with febrile illness, viral exanthema, symptoms of pericarditis, myocarditis, conjunctivitis, or pleurodynia (chest/abdominal pain associated with other viral prodrome), and symptoms of hand-foot-mouth disease.

Mumps infection may be indicated by meningeal symptoms following the onset of parotitis or orchitis. Epstein Barr Virus and Cytomegalovirus infection can be suggested by meningitis with mononucleosis syndrome. Varicella and CMV meningitis are more common in the immune-compromised host, e.g. transplant recipients.

Treatment

Treatment of viral meningitis is usually supportive only. If CSF analysis identifies a viral cause, antibiotics and steroids should be discontinued. Early treatment with aciclovir is found to be beneficial only in herpes encephalitis but not for meningitis. Ganciclovir for CMV is reserved for severe cases with positive CMV culture or when a congenital infection or an AIDS-related infection is suspected.