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  • Updated 08.17.2023
  • Released 02.22.1995
  • Expires For CME 08.17.2026

Viral meningitis



Meningitis is an inflammatory condition of the coverings of the brain and spinal cord and can occur in the setting of infection, autoimmune disorders, medications, and neoplasia (116; 60). Viral causes of meningitis are more common than bacterial etiologies in industrialized countries and occur more frequently in children under 5 years of age and in immunocompromised individuals. The annual incidence of viral meningitis is estimated to be between 0.26 and 17 cases per 100,000 persons in the United States, with an annual cost of $200 to $300 million (81; 97). Enteroviruses cause most viral meningitis cases, with up to 19 cases per 100,000 persons annually, followed by herpes simplex virus 2 and varicella zoster virus. West Nile virus can also cause meningitis in addition to other central nervous system complications and is currently the most common cause of summer epidemic viral meningitis in the United States (97).

Key points

• The most common symptoms of viral meningitis are acute onset of fever, headache, neck stiffness, and photophobia.

• Adults are more likely to present with meningeal signs than children whereas children more frequently develop respiratory symptoms, fever, and leukocytosis.

• Nonpolio enteroviruses account for most viral meningitis cases in the United States (up to 61% of cases), followed by herpes simplex and varicella zoster virus (40; 116).

• Viral meningitis and bacterial meningitis cannot be reliably differentiated based on symptoms and signs; therefore, cerebrospinal fluid analysis is needed.

• CSF will classically show a lymphocytic pleocytosis (usually fewer than 300 cells/mm3), a normal glucose concentration, normal or mildly elevated protein concentration, a negative Gram stain, and negative bacterial culture.

• A substantial percentage (up to 30%) of acute lymphocytic meningitis cases are never linked to a specific organism despite exhaustive evaluation (62).

Historical note and terminology

In 1890, Heinrich Quincke, a German internist and surgeon, introduced the lumbar puncture as a medical procedure in a patient with suspected meningitis and over a hundred years later this procedure remains the pivotal tool for diagnosis (90). In 1925 Wallgren recognized viruses as a cause of aseptic meningitis (112). In the early part of the 20th century, meningeal inflammation was recognized as part of paralytic poliomyelitis and epidemic parotitis. In the 1930s, filterable agents (viruses) were recovered from the CSF of patients with aseptic meningitis (lymphocytic choriomeningitis virus) (94).

Subsequently, aseptic meningitis was recognized as a syndrome that could have multiple causes, both infectious and noninfectious (113; 02; 117). The syndrome consists of symptoms and signs of meningeal irritation, a CSF white blood cell pleocytosis, and negative stains and cultures for bacteria, fungi, and parasites.

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