Anthrax

Anthrax-Microbiology

• Bacillus anthracis-gram +, spore-forming, bacillus
• Spores may remain infectious in environment for as long as 50 years
• Endemic infection in animals
• Spores enter host, germinate in a macrophage and are transported to regional lymph nodes where local toxins cause edema and death of tissue
• Humans develop infection naturally from handling contaminated fluids or hides ("Woolsorters Disease") or eating contaminated raw or undercooked meat

Anthrax: Inhalational, N=10

• Incubation (known for 6 cases)
• Range: 4-6 days
• Median: 4 days
• Age
• Range: 43-73
• Median: 56 years
• 7 of 10: male

Symptom Number

• Myalgias 6
• Headache 5
• Confusion 4
• Abdominal pain 3
• Sore throat 2
• Rhinorrhea 1

Anthrax: Inhalational, N=10

• WBC: Median 9.8 (7.5 - 13.3)
  • Differential - neutrophilia (>70%) in 7 of 10
• Elevated transaminases (9 of 10)
• Hypoxemia 6 of 10
• CXR: abnormal in all
• 2-initial reading WNL
• 8-pleural effusions
  • Often large, hemorrhagic, reaccumulated
• 7-mediastinal widening
• 7-infiltrates (some multilobar)
• CT (N=8): Mediastinal changes present in all

Anthrax: Inhalational, N=10

• Confirmation of Bacillus anthracis
• 7-positive blood cultures
  • Blood cultures positive in all who had not received antimicrobials
• Negative cultures
  • Bronchial or pleural biopsy-specific immunohistochemical staining
  • PCR
  • 4x rise in IgG to protective antigen (with confirmatory inhibition test)

Anthrax: Patient requests for testing

• There are no screening tests for anthrax
• Nasal swabs are
• A research tool
• ONLY used as part of an epidemiological investigation of KNOWN anthrax exposure
• Are NOT used to determine who should be treated or prophylaxed
• Should only be done at the request of Public Health

Anthrax: Patient requests for testing, cont.

• Asymptomatic patient WITHOUT known exposure:
• Reassurance
• No lab tests
• Asymptomatic patient WITH suspected (as determined by law enforcement/FBI) or known exposure:
• Consult with Public Health for recommendations
• Patient with non-specific symptoms
• Reports having had an exposure to unknown substance-not evaluated by law enforcement
• Does not fit any known risk profile (occupation, previously identified exposures)
• Reassurance about rarity of infection and frequency of viral URIs
• Evaluate for symptoms
• If afebrile, instruct patient to monitor for fever and other symptoms

Anthrax: Cutaneous

• Incubation 1-12 days
• Skin lesion: Macule or papule è  vesicles è  ulcer è  depressed black eschar
• Initially often have pruritis
• Usually painless
• Vesicles may surround ulcer
• Edema usually develops, may be severe
• May have fever, malaise, headache, regional lymphangitis, painful lymphadenopathy

Anthrax: Cutaneous, cont.

• Dx:
• Vesicular fluid/exudate/inflammed area of eschar
  • Gram stain (may be falsely negative)
  • Culture
• Biopsy-
  • Immunohistochemical staining, PCR, silver stain
• Consider blood culture

Cutaneous Anthrax: D/dx

• Ecthyma
• Folliculitis
• Brown recluse spider bite
• Ecthyma gangrenosum
• Orf
• Pyoderma gangrenosum
• Sweet's syndrome

(http://www.acponline.org/-American College of Physicians)

Cutaneous Anthrax: Clues to the diagnosis

• Usually solitary lesion
• Initial pruritis
• Painless
• Most often on upper extremities
• Evolution to eschar formation
• Non-pitting edema
• Regional adenopathy
• May be associated with constitutional sx

Anthrax Treatment

• Inhalational
• Doxycyline or ciprofloxacin, IV
• Plus: 1 or 2 other drugs
  • Rifampin, clindamycin, chloramphenicol, vancomycin, clindamycin
• Not cephalosporins or trimethopirm-sulfamethoxazole

Anthrax Epi Investigation
CDC, as of December 5

• 22 cases
• 11 inhalational-5 deaths
• 11 cutaneous (7 confirmed, 4 suspected)
• All but 2 cases: postal employees or media-related
• NJ and Washington DC mail sorting facilities
• Widespread environmental contamination
• ~85 million pieces of mail processed after implicated letters passed through until shutdown
• Mail from these facilities distributed to metropolitan areas with 10.5 million people

Anthrax Epi Investigation
CDC, as of December 5, cont.

• Risk for additional inhalational cases due to exposure to cross-contamination is very low
• Persons remaining concerned about their risk may want to
• Not open suspicious mail
• Keep mail away from face when opening
• Don't sniff mail or contents
• Wash hands after handling mail
• However, efficacy of these measures unknown