Table 5.12.

Definitions of meningitis, meningococcal disease and encephalitis

• Confirmed meningitis: isolation of bacteria from CSF, blood or DNA detection through PCR from a patient with a CSF pleocytosis of white cells >10 cells/mm3. In neonates a pleocytosis of >20 white cells is accepted. Diagnosis is also accepted in case of postmortem diagnosis.

• Probable meningitis: the presence of clinical symptoms and signs of bacterial meningitis in the absence of laboratory confirmation.

• Meningococcal disease: a clinical condition caused by Neisseria meningitidis with purulent conjunctivitis, septic arthritis and septicaemia with or without meningitis.

• Aseptic meningitis: the presence of CSF white cell count >10 cells/mm3; CSF is negative for bacterial culture, occurring usually in summer months. Viruses are most common causes.

• Encephalitis: an inflammation of the parenchymal tissue of the brain caused by an infection producing varying degrees of impaired consciousness.