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- A clinical syndrome characterized by signs/symptoms of acute meningeal inflammation from a viral etiology
- Viral meningitis (VM) is the most common cause of aseptic meningitis (no identifiable bacterial pathogen in CSF).
- System(s) affected: nervous
- Estimated 30,000 to 75,000 VM cases and 26,000 to 42,000 VM hospitalizations annually in United States
- Most common form of infectious meningitis
- The annual incidence of VM is higher than all other causes of meningitis combined.
- Peaks June 1 to October 31
- Nonpolio enteroviruses and arthropod-borne viruses predominate in warm months (70% of cases July to October).
- Mumps usually occurs in the winter and spring, often in epidemics; rare due to MMR vaccination
Etiology and Pathophysiology
- In immunocompetent hosts, VM is generally caused by virus with neurotropic predilection.
- Less commonly, direct neural transmission occurs from an acute flare of a chronic viral illness (such as HSV) already present in an immunocompetent host.
- 85–95% of VM cases are caused by enterovirus family (often transmitted by the fecal–oral route), including coxsackievirus A and B, echovirus, and nonpolio E variants: E9 and E30.
- Less common: HSV-1, HSV-2, varicella-zoster virus (VZV), adenovirus, lymphocytic choriomeningitis virus (LCMV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), HIV, parvovirus B19, mumps, Toscana virus
- Parechovirus 3 is the most common cause of VM in infants <90 days old.
- Arthropod-borne viruses: West Nile virus, St. Louis encephalitis virus, California encephalitis virus
- Recurrent benign lymphocytic (Mollaret) meningitis is 80% associated with HSV-2.
- Close contact with known cases of VM
- Age (common in children <5 years)
- Immunocompromised host (more susceptible to CMV, HSV, and adenovirus)
Cases of VM in the elderly are rare (most common cause is VZV, HSV); consider alternative diagnoses (e.g., carcinomatous meningitis, medication-induced aseptic meningitis).
Limit exposure to known hosts; hand washing and general hygiene procedures
Commonly Associated Conditions
Encephalitis; neurologic deficits; myopericarditis; neonatal enteroviral sepsis