Viral meningitis

Murtaza S Khan MD (Dr. Khan of the Indiana University School of Medicine has no relevant financial relationships to disclose.)
Karen L Roos MD FAAN, editor. (Dr. Roos of Indiana University School of Medicine has no relevant financial relationships to disclose.)
Originally released February 22, 1995; last updated July 17, 2017; expires July 17, 2020


About 36,000 cases of viral meningitis are estimated to occur in the United States each year. Enteroviruses cause most cases of viral meningitis. In this article, the author reviews the basic diagnosis and management of viral meningitis.

Key points


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


• Non-polio enteroviruses account for the majority of viral meningitis cases in the United States.


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


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

Historical note and terminology

In 1925 Wallgren recognized viruses as a cause of aseptic meningitis (Wallgren 1925). In the early part of this century, it was known that meningeal inflammation occurred 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) (Rivers and Scott 1935).

Subsequently, it was recognized that aseptic meningitis was a syndrome that could have multiple causes, both infectious and noninfectious (Wallgren 1951). The syndrome consists of symptoms and signs of meningeal irritation, a CSF pleocytosis, and negative stains and cultures for bacteria, fungi, and parasites. Viral meningitis causes the vast majority of cases of aseptic meningitis.

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