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  • Gram positive rod, Bacillus anthracis, which is capable of surviving inhospitable conditions through the formation of endospores
  • Incubation period is 10 days with no ability for human to human transmission and therefore, no need for respiratory isolation
    • Though human to human transmission does not occur, potential harbors of spores (patient clothes) need to be isolated and decontaminated with 10% bleach[1]
  • In general there is cutaneous, inhalational, and gastrointesinal anthrax.

Clinical Features

Cutaneous anthrax lesion on neck.
Cutaneous anthrax
A skin lesion with black eschar characteristic of anthrax
Cutaneous anthrax with associated marked edema.
Initial skin lesion with black eschar and red border. By the time the picture was taken, the massive associated edema of hand and arm had subsided.

Inhalational (5%)

  • Biphasic course

Prodrome Period

Acute phase

Cutaneous (95%)

  • The disease will start as an area of erythema and edema and progress to a vesicle which ruptures forming a central black eschar which eventually falls off
  • Total course of lesion evolution occurs over 1 week
  • Small minority of untreated patients develop rapidly fatal bacteremia [3]


Differential Diagnosis

Cutaneous (painless)


Lower Respiratory Zoonotic Infections

Bioterrorism Agents[5]

Category A

Category B

  • Ricin
  • Brucellosis
  • Epsilon toxin
  • Psittacosis
  • Q Fever
  • Staph enterotoxin B
  • Typhus
  • Glanders
  • Melioidosis
  • Food safety threats
  • Water safety threats
  • Viral encephalitis

Category C


CXR of inhalational anthrax showing mediastinal widening.
  • CXR/CT
    • Widened mediastinum representing hemorrhagic mediastinitis
    • Infiltrate, pleural effusion
    • Hyperdense mediastinal lymphadenopathy


Contact CDC Emergency Hotline 1-707-488-7100 for all suspected bioterrorism cases

Postexposure Prophylaxis

Patient should be vaccinated at day #0, #14, #28

Cutaneous Anthrax (not systemically ill)

  • Ciprofloxacin 500mg PO q12hrs x 60 days
  • Doxycycline 100mg PO q12hrs x 60 days

Inhalation or Cutaneous with systemic illness

Pediatric Postexpsoure Prophylaxis

Pediatric Cutaneous Anthrax (not ill)

  • Same as post exposure dosing and duration

Pediatric Inhalational or Cutaneous (systemically ill


  • Admit

See Also


  1. Heninger SJ et al. Decontamination of Bacillus anthracis Spores: Evaluation of Various Disinfectants. Appl Biosaf. 2009 Jan 1; 14(1): 7–10.
  2. Medscape: Anthrax
  3. Gordon, David. "Zoonotic Infections." Tintinalli's Emergency Medicine Manual, 8e Tintinalli JE, Ma O, Yealy DM, Meckler GD, Stapczynski J, Cline DM, Thomas SH.
  4. CDC. Gastrointestinal anthrax after an animal-hide drumming event - New Hampshire and Massachusetts, 2009. MMWR Morb Mortal Wkly Rep. 2010 Jul 23;59(28):872-7.
  5. Accessed 02/26/16