Clinical Review

Viral meningitis

BMJ 2008; 336 doi: http://dx.doi.org/10.1136/bmj.39409.673657.AE (Published 03 January 2008) Cite this as: BMJ 2008;336:36
  1. Sarah A E Logan, specialist registrar,
  2. Eithne MacMahon, consultant
  1. 1Infection and Immunology, Guy’s and St Thomas’ NHS Foundation Trust, London SE1 7EH
  1. Correspondence to: E MacMahon eithne.macmahon{at}gstt.nhs.uk
  • Accepted 21 November 2007

Viral meningitis is common and often goes unreported. In the absence of a lumbar puncture, viral and bacterial meningitis cannot be differentiated with certainty, and all suspected cases should therefore be referred. Lumbar puncture and analysis of cerebrospinal fluid may be done primarily to exclude bacterial meningitis, but identification of the specific viral cause is itself beneficial. Viral diagnosis informs prognosis, enhances care of the patient, reduces the use of antibiotics, decreases length of stay in hospital, and can help to prevent further spread of infection. Over the past 20 years, vaccination policies, the HIV epidemic, altered sexual behaviour, and increasing travel have altered the spectrum of causative agents. In this review we outline the changing epidemiology, discuss key clinical topics, and illustrate how identification of the specific viral cause is beneficial. Neonatal meningitis may be a component of perinatal infection and is not covered here.

Summary points

  • Bacterial and viral meningitis cannot reliably be differentiated clinically, and all suspected cases should be referred to hospital

  • Viral meningitis is most common in young children; the incidence decreases with age

  • Enteroviruses are the most common cause at all ages

  • Although most cases are self limiting, morbidity may be considerable

  • Herpes simplex virus causes viral meningitis, which may recur

  • Genital herpes infection may be acquired from a partner after many years within a monogamous relationship

  • Meningitis is a feature of HIV seroconversion

  • In the absence of associated encephalitis, the prognosis is usually good

Definitions

  • Meningitis—Inflammation of the meninges associated with an abnormal number of cells in the cerebrospinal fluid1

  • Aseptic meningitis—A syndrome characterised by acute onset of meningeal symptoms and fever, with pleocytosis of the cerebrospinal fluid and no growth on routine bacterial culture2

  • Mononuclear pleocytosis—An elevated white cell count in the cerebrospinal fluid, with predominant mononuclear cells (as opposed …

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