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Key Features

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Essentials of Diagnosis
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  • Fever, headache, vomiting, convulsions, shock (meningitis)

  • Fever, shock, petechial or purpuric skin rash (meningococcemia)

  • Diagnosis confirmed by culture of normally sterile body fluids

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General Considerations
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  • Meningococci (Neisseria meningitidis) may be carried asymptomatically for months in the upper respiratory tract

  • Less than 1% of carriers develop disease

  • Meningitis and sepsis are the two most common forms of illness

  • However, septic arthritis, pericarditis, pneumonia, chronic meningococcemia, otitis media, conjunctivitis, and vaginitis also occur

  • Patients deficient in one of the late components of complement (C6, C7, C8, or C9) are uniquely susceptible to meningococcal infection, particularly group A meningococci

  • Deficiencies of early and alternate pathway complement components also are associated with increased susceptibility

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Demographics
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  • Meningococcal cases in the United States have declined recently; currently there are about 800–1000 cases annually

  • Highest attack rate for meningococcal meningitis is in the first year of life, with a secondary peak during the teen years

  • In the United States, serogroups B, C, and Y each account for about 30% of cases; however, this distribution varies significantly with age

  • In infants about half the cases are caused by serogroup B

  • In adolescents, serogroups B, C, and W-135 cause most cases

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Clinical Findings

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Symptoms and Signs
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Meningococcemia
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  • A prodrome of upper respiratory infection is followed by high fever, headache, nausea, marked toxicity, and hypotension

  • Purpura, petechiae, and occasionally bright pink, tender macules or papules over the extremities and trunk are seen

  • Rash may occasionally be absent but usually progresses rapidly

  • Fulminant meningococcemia

    • Characterized by disseminated intravascular coagulation (DIC), massive skin and mucosal hemorrhages, and shock

    • May also be caused by Haemophilus influenzae, Streptococcus pneumoniae, or other bacteria

  • Chronic meningococcemia

    • Characterized by periodic bouts of fever, arthralgia or arthritis, and recurrent petechiae

    • Splenomegaly often is present

    • Patients may be free of symptoms between bouts

    • Occurs primarily in adults and mimics Henoch-Schönlein purpura

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Meningitis
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  • In many children, meningococcemia is followed within a few hours to several days by symptoms and signs of acute purulent meningitis, with severe headache, stiff neck, nausea, vomiting, and stupor

  • Children with meningitis generally fare better than children with meningococcemia alone, probably because they have survived long enough to develop clinical signs of meningitis

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Differential Diagnosis
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  • The skin lesions of H influenzae or pneumococci, enterovirus infection, endocarditis, leptospirosis, Rocky Mountain spotted fever, other rickettsial diseases, Henoch-Schönlein purpura, and blood dyscrasias may be similar to meningococcemia

  • Severe S aureus sepsis has been reported in some patients in whom purpura is present

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Diagnosis

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Laboratory Findings
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  • Peripheral WBC count may be either low or elevated

  • Thrombocytopenia may be present with or without DIC

  • If petechial or hemorrhagic lesions ...

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