Meningococcal Disease (Neisseria meningitidis)
2015 Case Definition

Background

During 2005-2011, an estimated 800-1,200 cases of meningococcal disease occurred annually in the United States, representing an incidence of 0.3 cases per 100,000 population. Incidence has declined annually since a peak of disease in the late 1990s. Although disease incidence is currently at historic lows, the overall case-fatality ratio remains at 10%-15%, and 11%-19% of survivors have long term sequelae (e.g., neurologic disability, limb or digit loss, and hearing loss).

Serogroups B, C, and Y are the major causes of meningococcal disease in the United States, each accounting for approximately one third of cases. However, the proportion of cases caused by each serogroup varies by age group. Approximately 60% of disease among children 0-59 months is caused by serogroup B N. meningitidis, which is not prevented by currently licensed vaccines. Serogroups C, Y, or W, which are included in vaccines available in the United States, cause 73% of all cases of meningococcal disease among persons aged ≥11 years.

In the United States, approximately 98% of cases of meningococcal disease are sporadic; however, outbreaks of meningococcal disease continue to occur. With high rates of vaccination with the quadrivalent meningococcal conjugate vaccine in adolescents and college-aged persons, outbreaks of serogroup C and Y disease are rare in this age group. Several recent outbreaks of serogroup B meningococcal disease on college campuses highlight the challenge of control of serogroup B meningococcal disease. Surveillance for meningococcal disease is needed to monitor trends in disease incidence, changes in epidemiology and serogroup distribution, and the effect of vaccination on the incidence of disease.

Clinical Criteria

Clinical purpura fulminans in the absence of a positive blood culture.

Laboratory Criteria For Diagnosis

• Gram-negative diplococci, not yet identified, isolated from a normally sterile body site (e.g., blood or CSF)
• Detection of N. meningitidis antigen
  • In formulin-fixed tissue by immunohistochemistry (IHC); or
  • In CSF by latex agglutination
• Detection of N. meningitidis-specific nucleic acid in a specimen obtained from a normally sterile body site (e.g., blood or CSF), using a validated polymerase chain reaction (PCR) assay; or
• Isolation of N. meningitidis
  • From a normally sterile body site (e.g., blood or CSF, or less commonly, synovial, pleural, or pericardial fluid); or
  • From purpuric lesions

Epidemiologic Linkage

Not applicable for case classification.

Suspected

• Clinical purpura fulminans in the absence of a positive blood culture; or
• Gram-negative diplococci, not yet identified, isolated from a normally sterile body site (e.g., blood or CSF)

Probable

• Detection of N. meningitidis antigen
  • In formulin-fixed tissue by immunohistochemistry (IHC); or
  • In CSF by latex agglutination

Confirmed

• Detection of N. meningitidis-specific nucleic acid in a specimen obtained from a normally sterile body site (e.g., blood or CSF), using a validated polymerase chain reaction (PCR) assay; or
• Isolation of N. meningitidis
  • From a normally sterile body site (e.g., blood or CSF, or less commonly, synovial, pleural, or pericardial fluid); or
  • From purpuric lesions

• Meningococcal Disease (Neisseria meningitidis) | 2010 Case Definition
• Meningococcal Disease (Neisseria meningitidis) | 2005 Case Definition
• Meningococcal Disease (Neisseria meningitidis) | 1997 Case Definition
• Meningococcal Disease (Neisseria meningitidis) | 1990 Case Definition