Plague Summary
Plague is an infectious disease caused by the Yersinia pestis bacteria, which is primarily found in rodents the fleas that feed off of them. The bacteria are passed to humans through flea or rodent bites. There are three forms of plague: bubonic, septicemic, and pneumonic. The symptoms and method of transmission vary with each form of plague. Plague can be treated with antibiotics.
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Plague facts

  • A bacterium, Yersinia pestis, causes the disease in animals and humans.
  • Plague is a disease that is transmitted from infected animals, usually fleas, to humans. Plague then may be transmitted from humans to others by direct contact or by touching or breathing droplets that contain the bacterium, Yersinia pestis. Untreated plague causes much suffering and deaths in humans.
  • Symptoms of plague vary and are grouped into three types:
    • Bubonic plague: The lymph nodes become swollen, tender, and are termed buboes. The patient may also develop fever, chills, and weakness.
    • Septicemic plague: In general, septicemic plague patients do not develop buboes. Instead signs and symptoms may include fever, chills, weakness, bleeding under the skin, abdominal pain, and septic shock with low blood pressure.
    • Pneumonic plague: Shortness of breath, cough (sometimes with bloody sputum), and chest pain quickly develop along with weakness, fever, and headaches.
  • Plague is preliminarily diagnosed by physical examination and by cultures of blood or other sites; definitive diagnosis is done by immunological tests that identify Y. pestis specifically.
  • Plague is treated by several types of antibiotics.
  • The history of plague infections of humans is extensive, and plague bacteria are considered to be biological weapons by some governments.
  • Although plague is endemic in some animal populations, fleas can transfer Y. pestis from animals to man; once a person is infected, the disease can easily be transmitted to other humans by direct and indirect contact with droplets or material touched by the infected person.
  • Prevention of plague is done by eliminating areas where animals, especially rodents, congregate and by avoiding the fleas the rodents carry. Some infections can be prevented by taking antibiotics soon after exposure to the disease.
  • There are no commercially available vaccines against plague; however, there is a small amount available from the U.S. government for researchers who work with Y. pestis.
  • Ongoing research includes trying to develop a plague vaccine with few side effects; others are exploring the Y. pestis genome for insights into its pathogenic mechanisms.
Medically Reviewed by a Doctor on 10/30/2013

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