Plague

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Background

  • The plague is a severe, acute infection caused by Gram Negative bacillus, Yersinia pestis.
    • Y. pestis is transmitted by fleas (vector) and occurs naturally in a variety of animals, including rodents (reservoir) [1]
  • Two main forms are bubonic and pulmonic forms
  • Considered a Class A bioterrorism agent

Clinical Features

Bubonic plague

  • Eschar often forms at site of vector bite (usually flea bite)
  • Buboes (inflamed, necrotic or hemorrhagic lymph nodes) are pathognomonic
    • Usually in axilla or groin
    • Typically non-fluctuant, but can suppurate (rare)
  • Liver and splenic involvement
  • Septicemia
    • The disease disseminates in about 50% of patients
  • Death if untreated in 2-10 days

Pulmonic plague

  • Very contagious
  • Can be hematogenous or aerosolized (weapon form)
  • Hemoptysis
  • Mulilobar hemorrhagic pneumonia
  • Sepsis
  • Death if untreated in 48 hours
    • Mortality rate nearly 100% without treatment [2]

Differential Diagnosis

Lower Respiratory Zoonotic Infections

Bioterrorism Agents[3]

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

Lymphadenopathy

Evaluation

Should be considered in any patient with clinical signs of plague and a recent history of travel to the western United States or any other plague endemic area.

Possible diagnostic samples:

  • Lymph node aspirate
    • Affected bubo should contain numerous organisms that can be evaluated microscopically and by culture.
  • Blood cultures
    • Organisms may be seen in blood smears if the patient is septicemic.
    • Blood smears taken from suspected bubonic plague patients early in the course of illness are usually negative for bacteria by microscopic examination but may be positive by culture.
  • Sputum
    • Culture is possible from sputum of very ill pneumonic patients
    • However, blood is usually culture-positive at this time as well.
  • Bronchial/tracheal washing
    • May be taken from suspected pneumonic plague patients
    • Not ideal for isolation of plague, since they often contain many other bacteria that can mask the presence of plague.

Gram, Wright, Giemsa, or Wayson's stained smears of peripheral blood, sputum, or lymph node specimen. Visualization of bipolar-staining, ovoid, Gram-negative organisms with a "safety pin" appearance permits a rapid presumptive diagnosis of plague.

  • If cultures yield negative results, and plague is still suspected, serologic testing is possible to confirm the diagnosis.
    • One serum specimen should be taken as early in the illness as possible, followed by a convalescent sample 4-6 weeks or more after disease onset.

Management

Droplet precautions if pneumonic form suspected

  • Plague is a reportable disease to the CDC
  • If bioterrorism suspected, health authorities must be contacted immediately
  • Consult ID
  • Do not perform an I&D as the buboes are responsive to antibiotics; performing an I&D risks disseminating the bacterium to health-care providers [4]

Antibiotics

Should be given within 24 hours for effective outcomes and continued for at least 10 days [5]

Postexposure Prophylaxis

Active Disease

Disposition

  • Admit
    • Droplet precautions if pneumonic form suspected for at least 4 days after initiation of antibiotics [6]

See Also

References

  1. Schultz, C., & Koenig, K. Weapons of Mass Destruction. In Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed.). Philadephia, PA: Elsevier/Saunders.
  2. Schultz, C., & Koenig, K. Weapons of Mass Destruction. In Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed.). Philadephia, PA: Elsevier/Saunders.
  3. https://www.niaid.nih.gov/topics/biodefenserelated/biodefense/pages/cata.aspx Accessed 02/26/16
  4. Schultz, C., & Koenig, K. Weapons of Mass Destruction. In Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed.). Philadephia, PA: Elsevier/Saunders.
  5. Schultz, C., & Koenig, K. Weapons of Mass Destruction. In Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed.). Philadephia, PA: Elsevier/Saunders.
  6. Schultz, C., & Koenig, K. Weapons of Mass Destruction. In Rosen's Emergency Medicine: Concepts and Clinical Practice (9th ed.). Philadephia, PA: Elsevier/Saunders.