A relatively common but rarely serious clinical syndrome with multiple viral etiologies, characterized by sudden onset of febrile illness with signs and symptoms of meningeal involvement. CSF findings are pleocytosis (usually mononuclear, occasionally polymorphonuclear in early stages), increased protein, normal sugar and absence of bacteria. A rubella-like rash characterizes certain types caused by echoviruses and coxsackieviruses; vesicular and petechial rashes may also occur. Active illness seldom exceeds 10 days. Transient paresis and encephalitic manifestations may occur; paralysis is unusual. Residual signs lasting a year or more may include weakness, muscle spasm, insomnia and personality changes. Recovery is usually complete. GI and respiratory symptoms may be associated with enterovirus infection.
Various diseases caused by non-viral infectious agents may mimic aseptic meningitis: these include inadequately treated pyogenic meningitis, tuberculous and cryptococcal meningitis, meningitis caused by other fungi, cerebrovascular syphilis, and lymphogranuloma venereum. Post-infectious and post-vaccinal reactions require differentiation from sequelae to measles, mumps, varicella and immunization against rabies and smallpox; these syndromes are usually encephalitic in type. Leptospirosis, listeriosis, syphilis, lymphocytic choriomeningitis, viral hepatitis, infectious mononucleosis, influenza and other diseases may produce the same clinical syndrome, as discussed in the chapters dealing with those diseases.
Infection by enteroviruses transmitted from the mother is a frequent cause of neonatal fever with neurological signs. In countries that are polio-free, the most prevalent infectious agent causing paralysis is enterovirus 71, responsible for outbreaks of meningitis and paralysis in many countries. Children and adults with B cell deficiencies are subject to chronic relapsing meningitis, usually caused by enteroviruses.
Under optimal conditions, specific identification is possible in about half of all cases, through serological and isolation techniques. Viral agents may be isolated in early stages from throat washings and stool, occasionally from CSF and blood, and through cell culture techniques and animal inoculation. PCR identification in CSF (and stool for enteroviruses) yields a more rapid diagnosis and probes are available for the identification of most viruses.
A wide variety of infectious agents exist, many associated with other specific diseases. Several viruses can produce meningeal features. At least half of cases have no obvious cause. In epidemic periods, mumps may be responsible for more than 25% of cases of established etiology in non-immunized populations. In the USA, enteroviruses (picornaviruses) cause most cases of known etiology, followed by coxsackievirus. These include coxsackievirus group B types 1–6 and echovirus types 2, 5, 6, 7, 9 (most), 10, 11, 14, 18 and 30, and enterovirus 71. Coxsackievirus group A (types 2, 3, 4, 7, 9 and 10), arboviruses, measles, herpes simplex and varicella viruses, lymphocytic choriomeningitis virus, adenovirus and others provide sporadic cases. Incidence of specific types varies with geographic location and time. Leptospira may cause up to 20% of cases of aseptic meningitis in various areas (see Leptospirosis).
Worldwide, as epidemics and sporadic cases; true incidence unknown. Seasonal increases in late summer and early autumn are due mainly to arboviruses and enteroviruses, while late winter outbreaks may be due primarily to mumps.
Reservoir, Mode of transmission, Incubation period, Period of communicability and Susceptibility
Vary according to the specific infectious agent (please see specific disease chapters).
Methods of control
- Preventive measures: Depend on causes (please see specific disease chapters).
- Control of patient, contacts and the immediate environment:
- Report to local health authority: In selected endemic areas; in many countries not a reportable disease, Class 3 (see Reporting). If laboratory-confirmed, specify infectious agent; otherwise, report as “cause undetermined.”
- Isolation: Specific diagnosis depends on laboratory data not usually available until after recovery. Therefore, enteric precautions are indicated for 7 days after onset of illness, unless a non-enteroviral diagnosis is established.
- Concurrent disinfection: No special precautions needed beyond routine sanitary practices.
- Quarantine: Not applicable.
- Immunization of contacts: See specific infectious agent.
- Investigation of contacts and source of infection: Not usually indicated.
- Specific treatment: Acyclovir may be given for herpes simplex meningitis. Pleconaril is available experimentally for enteroviral infections in many industrialized countries. In the rare event of agammaglobulinemia with chronic enteroviral meningitis, patients should receive IG.
- Epidemic measures: See specific infectious agent.
- Disaster implications: None.
- International measures: WHO Collaborating Centres provide support as required. More information can be found at:
322.0 (nonpyogenic Meningitis)
G03.0 (nonpyogenic Meningitis)
[CCDM19: Editorial Board]
[CCDM18: D. Lavanchy]
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