Meningococcemia

Basics

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

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