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  • Anthrax can be transmitted by inhalation, ingestion, or inoculation.  Inhalation is most likely during a bioterrorist attack).
  • The spore form of anthrax is highly resistant to physical and chemical agents.  Spores can persist in the environment for years.
  • Anthrax is not transmitted from person-to-person.


  • Incubation period is 1-5 days (range sometimes up-to 43 days).
  • Inhaling anthrax presents itself as acute hemorrhagic mediastinitis.
  • Biphasic illness, with initial phase of non-specific flu-like illness, followed by acute phase of respiratory distress and toxemia (sepsis).
  • Chest x-ray findings: Mediastinal widening in a previously-healthy patient in the absence of trauma is pathognomonic for anthrax.
  • Mortality rate for inhalation anthrax approaches 90%, with treatment. Shock and death within 24-36 hours.


Laboratory Diagnosis
  • Laboratory specimens should be handled in a "Biosafety Level 2" facility.
  • Gram stain shows gram positive bacilli, occurring singly or in short chains, often with squared off ends (safety pin appearance).  In advanced disease, a gram stain of unspun blood may be positive.
  • Distinguishing characteristics on culture include: non-hemolytic, non-motile, capsulated bacteria that are susceptible to gamma phagelysis.
  • ELISA and PCR tests are available at national reference laboratories.


Patient Isolation
  • Standard barrier isolation precautions.  Patients do not require isolation rooms.
  • Anthrax is not transmitted person-to-person.


  • Prompt initiation of antibiotic therapy is essential.
  • Antibiotic susceptibility testing is KEY to guiding treatment.
  • Ciprofloxicin (400 mg IV q 12 hr) is the antibiotic of choice for penicillin-resistant anthrax or for empiric therapy while awaiting susceptibility results.
  • All patients should be treated with anthrax vaccine if available.  Antibiotic treatment should be continued until three doses of vaccine have been administered (days 0, 14, and 28).  If vaccine is unavailable, antibiotic treatment should be continued for 60 days.


  • If vaccine is available, all exposed persons, as determined by local and state health depts, should be vaccinated with three doses of anthrax vaccine (days 0, 14, and 28).
  • Start antibiotic prophylaxis immediately after exposure with ciprofloxicin (500 mg po q 12 hrs) or doxycycline (100 mg po q 12 hrs).  If strain is penicillin-susceptible, therapy can be modified to penicillin or amoxicillin.
  • Antibiotic prophylaxis should be continued until three doses of vaccine have been administered.  If vaccine is unavailable, antibiotics should be continued for 60 days.

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