Plague (Bubonic, Pneumonic, Septicemic)

Infectious Agent

The gram-negative bacterium Yersinia pestis .


Usually through the bite of infected rodent fleas. Less common exposures include handling infected animal tissues (hunters, wildlife personnel), inhalation of infectious droplets from cats or dogs with plague, and, rarely, contact with a pneumonic plague patient.


Endemic in rural areas in central and southern Africa (especially eastern Democratic Republic of Congo, northwestern Uganda, and Madagascar), central Asia and the Indian subcontinent, the northeastern part of South America, and parts of the southwestern United States. Overall risk to travelers is low.

Clinical Presentation

Incubation period is typically 1–6 days. Symptoms and signs of the 3 clinical presentations of plague illness are as follows:

  • Bubonic (most common)—rapid onset of fever; painful, swollen, and tender lymph nodes, usually inguinal, axillary, or cervical
  • Pneumonic—high fever, overwhelming pneumonia, cough, bloody sputum, chills
  • Septicemic—fever, prostration, hemorrhagic or thrombotic phenomena, progressing to acral gangrene


Y. pestis can be isolated from bubo aspirates, blood cultures, or sputum culture if pneumonic. Diagnosis can be confirmed in public health laboratories by culture or serologic tests for the Y. pestis F1 antigen. Plague is a nationally notifiable disease.


Parenteral antibiotic therapy with streptomycin or gentamicin appears to be equally effective. Levofloxacin and ciprofloxacin have been approved by the Food and Drug Administration for treatment based on animal studies. Second-line agents include doxycycline, tetracycline, and chloramphenicol.


Reduce contact with fleas and potentially infected rodents and other wildlife. No plague vaccine is available for commercial use in the United States.

CDC website:


  1. Neerinckx S, Bertherat E, Leirs H. Human plague occurrences in Africa: an overview from 1877 to 2008. Trans R Soc Trop Med Hyg. 2010 Feb;104(2):97–103.  [PMID:19716148]
  2. Perry RD, Fetherston JD.Yersinia pestis --etiologic agent of plague. Clin Microbiol Rev. 1997 Jan;10(1):35–66.  [PMID:8993858]
  3. World Health Organization. Human plague: review of regional morbidity and mortality, 2004–2009. Wkly Epidemiol Rec. 2009 Feb 5;85(6):40–5.  [PMID:20151494]


Paul S. Mead