Plague

Background

• The plague is a severe, acute infection caused by Gram Negative bacillus, Yersinia pestis.
• 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
• Liver and splenic involvement
• Septicemia
• 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

Differential Diagnosis

Lower Respiratory Zoonotic Infections

• Psittacosis
• Anthrax (Bacillus anthracis)
• Brucellosis (Brucella species)
• Q fever (C. burnetti)
• Pasteurellosis (Pasteurella multocida)
• Melioidosis (Burkholderia pseudomallei)
• Rocky Mountain Spotted Fever (R. rickettsii)
• Pulmonic Plague (Yersinia pestis)
• Influenza A
• Hantavirus

Bioterrorism Agents

Category A

• Anthrax
• Smallpox
• Plague
• Tularemia
• Botulinum Toxin
• Viral hemorrhagic fever

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

• Influenza
• Yellow fever
• Tickborne hemorrhagic fever
• Tickborne encephalitis

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

Antibiotics

Postexposure Prophylaxis

• Doxycycline 100mg (2.2mg/kg) PO q12hrs daily OR
• Ciprofloxacin 500mg (20mg/kg) PO q12hrs daily OR
• Chloramphenicol 1mg (25mg/kg) PO q6hrs
  • only if age > 2

Active Disease

• Gentamicin 5mg/kg IV/IM once daily x 10 days OR
• Ciprofloxacin 500mg (20mg/kg) PO q12hrs x 10 days OR
• Doxycycline 200mg (2.2mg/kg) PO/IV daily

Disposition

• Admit
  • Droplet precautions if pneumonic form suspected

See Also

• Isolation Precautions
• Bioterrorism
• GEMC:Prehospital / Disaster / Mass Casualty Medicine

References

Authors

Ross Donaldson, Jonathan Osgood, Daniel Eggeman, Daniel Ostermayer, Neil Young