Meningitis

Meningitis describes an inflammation of membranes that surround the brain (pia mater, arachnoid and the interposed cerebro spinal fluid). The inflammation may spread around the brain, spinal cord and the ventricles through the subarachnoid space (1). As such it represents a manifestation of a variety of diseases with varying severity.

Meningitis can be divided into:

• bacterial - positive CSF Gram stain and positive CSF bacterial with an increased polymorphonuclear leucocytes in the CSF
• aseptic - no evidence of pyogenic bacterial infection on Gram’s stain or culture and usually accompanied by a mononuclear leucocytes in CSF
  • nonbacterial
    • viral
    • non viral - fungal, partially treated bacterial, meningial inflammation caused by adjacent pyogenic infections, TB, syphilis, Lyme disease
  • noninfectious
    • common systemic disease e.g. - sarcoidosis
    • neoplastic
    • drugs (1)

Ninety percent of all cases of meningitis occur within the first five years of life, the peak incidence being in the six to twelve month age range.

Under the Health Protection (Notification) Regulations 2010:

• acute meningitis (including bacterial meningitis) and meningococcal septicaemia are notifiable diseases
• from October 2010 the diagnostic laboratories will have to notify the Health Protection Agency after identifying infection caused by specific organisms, including N meningitides (2)

Reference:

• (1) Mace SE. Acute bacterial meningitis. Emerg Med Clin North Am. 2008;26(2):281-317
• (2) Visintin C et al. Management of bacterial meningitis and meningococcal septicaemia in children and young people: summary of NICE guidance. BMJ. 2010;340:c3209