• Bacterial illness caused by Neisseria meningitidis
  • Several forms of illness may occur
  • Mild presentation of meningococcemia may occur
  • Overwhelming meningococcal sepsis
  • Meningococcal meningitis
  • Chronic/occult meningococcemia
  • Septic arthritis
  • Acquired from close contact with an infected individual or an asymptomatic carrier
  • Intimate kissing and cigarette smoking are independent risk factors


  • N. meningitidis:
    • Serotypes A, B, C, D, H, I, K, L, X, Y, Z, 29E, and W135
    • Serotype B is most common in the U.S.
    • Majority of infections caused by A, B, C, X, Y, and W135
  • Bacteria attach to and enter nasopharyngeal epithelial cells
  • Bacteria spread from the nasopharynx through the bloodstream via entry of vascular endothelium
  • Most circulating meningococci are eliminated by the spleen
  • Meningococci produce an endotoxin (lipooligosaccharide):
    • Involved in pathogenesis of the skin, adrenal manifestations, and vascular collapse
  • Human oropharynx/nasopharynx is the only reservoir
  • Carrier usually has developed immunity to serotype-specific antibody (not immune to all serotypes):
    • Age <5 yr: 1% carrier rate
    • Age 20–40 yr: 30–40% carrier rate
    • Lower rate of immunity in children, which is reflected by the higher rates of infection
  • Most common in fall and spring
  • Increased incidence in military recruits and close living conditions
  • Epidemics—ages 5–9 yr most/earliest affected

There's more to see -- the rest of this topic is available only to subscribers.