Meningitis describes an inflammation of membranes that surround the brain (pia mater, arachnoid and the interposed cerebrospinal fluid). The inflammation may spread around the brain, spinal cord and the ventricles through the subarachnoid space. As such it represents a manifestation of a variety of diseases with varying severity. (1,2,3)
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
- non-infectious
- common systemic disease e.g. - sarcoidosis
- neoplastic
- drugs
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. Diagnostic laboratories have to notify the Health Protection Agency after identifying infection caused by specific organisms, including N meningitides
Reference:
- McGill F, Heyderman RS, Michael BD, et al. The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults. J Infect. 2016 Apr;72(4):405-38.
- Centers for Disease Control and Prevention. Meningitis: resources for healthcare professionals. Aug 2019 [internet publication].
- NICE. Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management. NICE guideline NG240. Published March 2024