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- A systemic infection with the bacterium Neisseria meningitidis, a gram-negative diplococcus that is relatively fastidious. Despite treatment with appropriate antibiotics, this disease may have a fulminant course (i.e., significant complications within hours of presentation) with a high likelihood of mortality.
- 13 serogroups have been described on the basis of capsular polysaccharide antigens; serotypes B, C, and Y account for most of the cases in the United States. Serogroup Y accounted for 30% of cases between 1996 and 1998.
- Isolation of the hospitalized patient; hospitalized patients require respiratory isolation until 24 hours after initiation of appropriate antibiotic therapy.
- Exposed contacts, including household, day care, and nursery school, should receive the following:
- Rifampin, 10 mg/kg (maximum 600 mg) PO q12h for 4 doses
- Contacts <1 month of age should receive rifampin 5 mg/kg PO q12h for 4 doses.
- Alternatively, ceftriaxone is also effective prophylaxis for contacts ≤15 years of age; a single dose of 125 mg IM is recommended.
- For contacts >15 years old, ceftriaxone 250 mg IM is recommended. Its safety profile is preferred for pregnant women.
- Medical personnel should receive prophylaxis only if they had close contact with respiratory secretions.
- Vaccines for types A, C, Y, and W-135 are available and produce an immune response in 10–14 days.
- A tetravalent conjugate meningococcal vaccine, MCV4, is licensed for use in people in the age range of 2–55 years. It is recommended in all unimmunized 11–12-year-old adolescents, with a booster dose at age 16 years.
- Serotype B vaccine was recently approved by the FDA and is licensed for use in people 10–25 years of age.
- The Centers for Disease Control and Prevention (CDC) continues to recommend routine adolescent immunization with the exception of persons with a history of Guillain-Barré syndrome (GBS) who are not in a high-risk group for invasive meningococcal disease. An updated fact sheet on GBS and MCV4 is available at http://www.cdc.gov/vaccinesafety/Concerns/gbsfactsheet.html. A study published in 2012 did not support an association between GBS and MCV4 vaccination.
- The rates of meningococcal disease in the United States have remained stable at 0.9–1.5 cases per 100,000 population per year.
- Children <5 years of age are most often affected, with peak incidence between 3 and 5 months of age.
- During epidemics, more school-aged children may be affected.
- The disease occurs most commonly in winter and spring months.
- Increased disease activity may follow an influenza A outbreak.
- Patients with asplenia, deficiencies of properdin C3, or a terminal complement component (C5–C9), and HIV are at increased risk for invasive and recurrent disease.
- Organism virulence factors, such as differences in the bacterial cell wall lipopolysaccharide, play a role in disease severity. Less virulent organisms are more likely in chronic meningococcemia, which has a favorable prognosis.
- Inherited deficiency of terminal complement may be found in 5–10% of patients during epidemics. The frequency increases to 30% in patients with recurrent disease.
- A number of other immune function–related genes associated with either susceptibility or protection from infection have been identified.
- Fulminant disease is signified by diffuse microvascular damage and disseminated intravascular coagulation (DIC); see “Diagnosis” section.
- Death results from effects of endotoxic shock, including circulatory collapse and myocardial dysfunction.
- Colonization and infection of the upper respiratory tract occurs after inhalation of, or direct contact with, the organism, usually in oral secretions.
- Disseminated disease occurs when the organism penetrates the nasal mucosa and enters the bloodstream, where it replicates.