TABLE 2.

Definitions of cases requiring public health action¹¹

Cases requiring public health action

Confirmed case

Clinical diagnosis of meningitis, septicaemia or other invasive disease (e.g. orbital cellulitis, septic arthritis)

AND at least one of:

• Neisseria meningitidis isolated from normally sterile site

• Gram negative diplococci in normally sterile site

• Meningococcal DNA in normally sterile site

• Meningococcal antigen in blood, CSF or urine.

NB: Although not meeting the definition of a confirmed case, meningococcal infection of the conjunctiva is considered an indication for public health action because of the high immediate risk of invasive disease.

Probable case

Clinical diagnosis of meningitis or septicaemia or other invasive disease where the consultant in health protection, in consultation with the physician and microbiologist, considers that meningococcal infection is the most likely diagnosis. Some microbiological tests (e.g. rising antibody levels) that are not considered sufficient to confirm the diagnosis of meningococcal disease may change the case category from ‘possible’ to ‘probable’.

Cases not requiring public health action

Possible case

Clinical diagnosis of meningitis or septicaemia or other invasive disease where the consultant in health protection, in consultation with the clinician and microbiologist, considers that diagnoses other than meningococcal disease are at least as likely. This category includes cases who may have been treated with antibiotics but whose probable diagnosis is viral meningitis. In such cases, prophylaxis for contacts is not indicated, but giving out information about meningococcal disease may be helpful.