Meningococcal infections are caused by Neisseria meningitidis. Invasive infection usually results in meningococcemia, meningitis or both. Strains belonging to groups A, B, C, Y, and W-135 account for most infections. Risk factors include inherited or acquired terminal complement deficiencies (C5 to C9), properdin deficiency, hypogammaglobulinemia, or asplenia (anatomic or functional). Children 2 years of age or younger (peak attack rate: infants <1 year) are most often affected, with another peak in adolescents (15 through 18 years of age). Incubation period is 1 to 10 days. Presenting signs and symptoms may be nonspecific mimicking a viral infection (eg, fever, chills, myalgias/weakness, headache), or septic shock, lethargy, coma, convulsion, signs of meningitis (nuchal rigidity, Kernig sign, and/or Brudzinski sign) or signs of multiorgan failure. Initially rash may begin as urticaria, macules or maculopapules, or petechiae that may coalesce to form larger ecchymotic areas with ischemic necrosis. Common sites for the rash are the trunk and extremities (may involve any area), mucous membranes (eg, palpebral conjunctivae), and clusters at pressure points. Differential diagnosis of purpura and petechial lesions includes septicemia with gram-negative or gram-positive organisms, enteroviral infections (eg, echovirus or coxsackie virus), Rocky Mountain spotted fever, Henoch-Schönlein purpura, petechiae from intractable coughing or vomiting, trauma (child abuse, accidental), factor deficiency (eg, hemophilia), measles/atypical measles, idiopathic thrombocytopenic purpura, thrombocytopenia from other etiology (eg, leukemia), drug reactions (eg, sulfonamides, penicillins), bacterial endocarditis, gonococcemia, epidemic typhus, Ehrlichia canis infection, and Stevens-Johnson syndrome.
Complications include disseminated intravascular coagulation (DIC), purpura fulminans, cardiac (eg, myocarditis, congestive heart failure), pulmonary (eg, pneumonia, lung abscess), neurologic sequelae from meningitis (eg, subdural effusion or empyema, brain abscess) and Waterhouse-Friderichsen syndrome (bleeding into adrenals, shock, coma, and death). Poor prognostic factors include hypotension, hypothermia, leucopenia, thrombocytopenia, absence of meningitis, purpura fulminans, petechiae <12 hours before presentation, seizures, or shock on presentation.