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The following text is from an archived Red Book® edition and may not reflect current recommendations or information. To view the current edition, click here.
Section 3. Summaries of Infectious Diseases
Anthrax
Clinical Manifestations
Etiology
Epidemiology
Diagnostic Tests
Treatment
Isolation of the Hospitalized Patient
Control Measures
CLINICAL MANIFESTATIONS: Depending on the route of infection, anthrax disease can occur in 3 forms: cutaneous, inhalational, and gastrointestinal. Cutaneous anthrax begins as a pruritic papule or vesicle that enlarges and ulcerates in 1 to 2 days, with subsequent formation of a central black eschar. The lesion usually is painless, with surrounding edema, hyperemia, and regional lymphadenopathy. Patients may have associated fever, malaise, and headache. Inhalational anthrax is the most lethal form of disease. A prodrome of fever, chills, nonproductive cough, chest pain, headache, myalgias, and malaise may occur initially, but more distinctive clinical hallmarks occur 2 to 5 days later and include a hemorrhagic mediastinal lymphadenitis, hemorrhagic pleural effusion, bacteremia, and toxemia resulting in severe dyspnea, hypoxia, and septic shock. A widened mediastinum is the classic finding on imaging of the chest but initially may be subtle. Gastrointestinal tract disease can present as 2 clinical syndromes, intestinal and oropharyngeal. Patients with the intestinal form have symptoms of nausea, anorexia, vomiting, and fever, progressing to severe abdominal pain, massive ascites, hematemesis, and bloody diarrhea. Oropharyngeal anthrax may include posterior oropharyngeal ulcers that typically are unilateral and associated with marked neck swelling, regional adenopathy, and sepsis. Hemorrhagic meningitis can result from hematogenous spread of the organism after acquiring any form of the disease. The case fatality ratio for patients with appropriately treated cutaneous anthrax usually is <1%, but for inhalational or gastrointestinal disease, mortality can exceed 50%.
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ETIOLOGY: Bacillus anthracis is an aerobic, gram-positive, encapsulated, spore-forming, nonmotile rod. Spore size is approximately 1 x 2 µm. Bacillus anthracis has 3 major virulence factors: an antiphagocytic capsule and 2 exotoxins, called lethal and edema toxins. The
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