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Plague  Lesson 7
 Veterinarian Issues

Plague Overview

  • Plague is an acute and potentially fatal bacterial infection that affects humans and most mammals. It is caused by Yersinia pestis, a Gram-negative, bipolar-staining, pleomorphic coccobacillus.
  • A bioterrorism-related release of Y. pestis could result in the infection of not only humans but also domestic and peri-domestic animals via:
    • inhalation of the primary aerosol,
    • ingestion of food or water exposed to the primary aerosol,
    • ingestion of another infected animal, or
    • flea bite from an infective flea (that had previously fed on a bacteremic animal).
  • Natural transmission cycles involving wild rodents and their fleas can be found in many regions of the western United States.
  • Occasionally, naturally occurring plague causes widespread outbreaks or epizootics among rodent populations.
  • While it appears that virtually any mammal can be infected with plague bacteria, some species do not develop clinical signs of illness following infection and are unlikely to pose great risks to humans.
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Infected Animals

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Dog with submandibular lymph node

Cat recovering from plague with submandibular bubo

Dead Ground Squirrel
Ground Squirrel

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Page last reviewed February 12, 2007
Page last modified September 7, 2004

  • Content source: CDC Emergency Risk Communication Branch (ERCB), Division of Emergency Operations (DEO), National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
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