Viral meningitis

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Viral meningitis
Classification and external resources
ICD-10	G0.2
ICD-9	321.2
eMedicine	article/1168529
MeSH	D008587

Viral meningitis is an inflammation of the meninges (the membranes covering the brain and spinal cord) caused by viral infection. It is also called aseptic meningitis or subsumed under lymphocytic choriomeningitis (LCM) due to its cerebrospinal fluid (CSF) test results. Based on clinical symptoms, viral meningitis cannot be differentiated from bacterial meningitis. Both appear as headache, fever, and neck stiffness but viral meningitis has no evidence of bacterial present in CSF. However, viral meningitis is less serious than bacterial meningitis. Therefore, CSF analysis is needed to identify the disease. In general, there are no medications to fight the virus that cause meningitis, so treatment is usually aimed at relieving the patient's symptoms by having a rest and fever-reducing medication.
Most cases are caused by enteroviruses (common stomach viruses).^[1][2] However, there is evidence that other viruses can also cause viral meningitis. For instance, West Nile virus, mumps, measles, herpes simplex types I and II, varicella, and lymphocytic choriomeningitis (LCM) virus.^[2][3]
In the United States 1988-1999, about 36,000 cases of viral meningitis are newly occurred each year.^[4] This disease can occur in both children and adult depending on specific viruses and epidemic area. For example an outbreak reported in Romania 1996, viral meningitis is more common among adults, as well as a 9-year Spanish study, it was more often seen in patients aged 15 years or older (66.1%; mean 30.2 yo).^[5] While, patients aged younger than 15 (mean 5.9 yo) was seen 33.8% of all cases.^[5] In contrast to a study in Finland 1966 and the outbreaks in Cyprus 1996, Gaza 1997, China 1998 and Taiwan 1998, the incidences of viral meningitis were more common among children.^[6][7][8][9]

Causes

Causative organisms include:^[10]

• Enteroviruses
  • Enterovirus 71
  • Echovirus
  • Poliovirus (PV1, PV2, PV3)
  • Coxsackie A virus (CAV); also causes Hand foot and mouth disease
• Herpesviridae (HHV)
  • Herpes simplex virus type 1 (HSV-1 / HHV-1) or type 2 (HSV-2 / HHV-2); also cause cold sores or genital herpes
  • Varicella zoster (VZV / HHV-3); also causes chickenpox and shingles (herpes zoster)
  • Epstein-Barr virus (EBV / HHV-4); also causes infectious mononucleosis/"mono"
  • Cytomegalovirus (CMV / HHV-5)
• Human Immunodeficiency Virus (HIV); causes AIDS
• La Crosse virus
• Lymphocytic choriomeningitis virus (LCMV)
• Measles
• Mumps
• St. Louis Encephalitis virus
• West Nile virus

Treatment

Herpes simplex virus, varicella zoster virus and cytomegalovirus have a specific antiviral therapy; most other viruses do not. For HSV the treatment of choice is acyclovir.^[11]