Viral meningitis

Viral or ‘aseptic’ meningitis is the most common type of meningitis.  It can be very debilitating but is generally far less severe than bacterial meningitis and is rarely fatal. Viral meningitis can be caused by many different viruses although the majority of cases are caused by members of the enterovirus family. 

Enteroviruses

Enteroviruses account for 85–95% of all identified cases of viral meningitis.  According to the CDC’s National Enterovirus Surveillance System,¹ the predominant enteroviruses isolated from patients in the US between 1997 and 1999 were echoviruses 30, 11, 9, 6 and 7; coxsackieviruses B1 and B3; enterovirus 71; coxsackievirus B4; and echovirus 25.

Infants are most susceptible to enteroviral meningitis but enteroviruses are also the most common causes of viral meningitis in adults, especially in immunodeficient or immunocompromised individuals.

Mumps virus

The mumps virus is a member of the paramyxovirus family and is one of the most common causes of viral meningitis in populations that have not been immunised.  Meningitis is the most common neurological manifestation of mumps infection and symptomatic meningitis is estimated to occur in 10–30%² of patients infected with the mumps virus.  Meningitis due to infection with mumps has been virtually eliminated due to the introduction of the MMR vaccine.

Herpesviruses

Herpes simplex virus types I and II account for 0.5–3.0%³ of cases of viral meningitis.  The infection is normally self-limiting, in contrast to herpes simplex encephalitis, which is potentially fatal.  Other members of the Herpesvirus family may also cause meningitis, for example Cytomegalovirus and Epstein-Barr virus may cause meningitis in association with mononucleosis syndrome, but these cases are very rare.  Varicella-zoster virus, the cause of chickenpox and shingles, can also cause meningitis.