Clinical evidence of invasive disease with laboratory confirmation of infection:
- isolation of N. meningitidis from a normally sterile site (blood, CSF, joint, pleural or pericardial fluid)
- demonstration of N. meningitidis DNA by an appropriately validated nucleic acid test (NAT) from a normally sterile site.
Clinical evidence of invasive disease with purpura fulminans or meningococcemia, with no other apparent cause, with non-confirmatory laboratory evidence:
- Gram-negative diplococci in the CSF
Clinical illness associated with invasive meningococcal disease usually manifests itself as meningitis and/or septicaemia, although other manifestations may be observed (e.g. orbital cellulitis, septic arthritis). Invasive disease may progress rapidly to purpura fulminans, shock and death.