Viral Meningitis

• Viral meningitis is common, especially in children.
• A study from Finland reported an incidence of approximately 200 per 100,000 in infants.
• In the UK it is estimated at 5-15 cases per 100,000.²
• In children, hospitalization is highest immediately after birth with a further secondary peak at age 5.³
• It may present identically to bacterial meningitis, the two can be distinguished based on findings on CSF analysis.

• Enteroviruses - commonest cause at all ages
• Herpes simplex viruses
• Varicella Zoster virus
• Human immunodeficiency virus (HIV)
• Epstein Barr virus
• Mumps virus
• Cytomegalovirus⁵
• Travel related - e.g. tick-borne meningoencephalitis

Enteroviruses⁴

• The name relates to how the virus enters the human body.
• They are a large group and include Coxsackie A and B viruses, echoviruses, polioviruses and enterovirus 71 (more recent).
• They all can invade the neurological system and cause inflammation.
• The commonest enteroviruses causing viral meningitis include Coxsackie B and echoviruses.
• It occurs mostly at a young age and infection is highest in summer and autumn in temperate areas.
• Viral meningitis from enteroviruses is self-limiting but headache can be severe and continue for days. It may also require admission for opiate analgesia.

Herpes simplex viruses (HSV-1, HSV-2)⁴

• HSV meningitis is a self-limiting illness in the immunocompetent and distinct from encephalitis (which is potentially life-threatening).
• HSV meningitis, if it is to occur, usually follows primary genital infection (more likely with HSV-2).

HIV viral meningitis⁶

• Seen in 5-10% of HIV infected patients.
• Meningitis can occur at the time the virus is acquired or during seroconversion.
• CSF findings are indistinguishable from other viral meningitides - thus it is difficult to diagnose HIV at the time.
• Furthermore, peripheral anti-HIV antibodies are likely to be negative during seroconversion.

This is similar to bacterial causes of meningitis.

Symptoms

• Fever
• Headache
• Photophobia
• Neck stiffness
• Confusion/delirium
• Rarely - seizures, fluctuation in GCS
• Specific features relating to causative virus e.g. vesicles in Coxsackie viruses or herpes related infections, rash in HIV seroconversion

Also enquire about recent travel, sexual history, and vaccinations received.

Signs

• High temperature
• Neck stiffness
• Pharyngitis
• Lymphadenopathy
• Focal neurological signs are usually not present
• Specific features relating to causative virus e.g. vesicles in Coxsackie viruses or herpes related infections, sacral radiculomyelitis in HSV-2 meningitis

• Other causes of meningitis or meningoencephalitis e.g. bacterial or tuberculosis meningitis, HSV meningoencephalitis.
• Any cause of headache e.g. subarachnoid haemorrhage, migraine.

• Full blood count, renal function and liver function tests may all be unremarkable
• CT brain is also likely to be unremarkable
• CSF (obtained via lumbar puncture):
  • WCC raised but usually lymphocytes predominate unlike bacterial causes
  • CSF glucose to plasma glucose ratio is usually >0.5
  • CSF protein raised (but < 1g per litre thus not as high as in bacterial meningitis)
  • CSF samples for virology - viral culture or PCR (more sensitive) looking for enteroviruses, herpes simplex virus etc⁴
  See CSF record.

• The general principles of management for all viral meningitis includes supportive therapy e.g. analgesia, antipyretics and hydration.
• More specific therapy depends on the causative organism e.g.
  • Enteroviral meningitis - usually self-limiting and no specific therapy required unless hypogammaglobulinaemia present (immunoglobulins used).
  • HSV-1 and 2 - antiviral therapy e.g. aciclovir is used early on, however there is no current evidence of its benefits. Patients should be considered for follow-up with sexual health clinic once they have recovered.

• HSV-2 meningitis can recur especially in women and those with primary genital infection.
• There have been rare reports of deaths in children with viral meningitis relating to cerebral oedema and cardiopulmonary collapse.⁸

Viral meningitis is usually a self-limiting disease and a full recovery is usually achieved after resolution.

Vaccines are available for the prevention of some viral meningitis such as those caused by mumps, measles, influenza, varicella and polio.