Plague

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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 by 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:
  • 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.
Reviewed by Mary D. Nettleman, MD, MS, MACP on 4/13/2012


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Plague Symptoms

Q. What is the incubation period for plague?
A. A person usually becomes ill with bubonic plague 2 to 6 days after being infected. When bubonic plague is left untreated, plague bacteria invade the bloodstream. When plague bacteria multiply in the bloodstream, they spread rapidly throughout the body and cause a severe and often fatal condition. Infection of the lungs with the plague bacterium causes the pneumonic form of plague, a severe respiratory illness. The infected person may experience high fever, chills, cough, and breathing difficulty, and expel bloody sputum. If plague patients are not given specific antibiotic therapy, the disease can progress rapidly to death.

Q. What is the mortality rate of plague?
A. About 14% (1 in 7) of all plague cases in the United States are fatal.

Q. How many cases of plague occur in the U.S.?
A. Human plague in the United States has occurred as mostly scattered cases in rural areas (an average of 10 to 20 persons each year). Globally, the World Health Organization reports 1,000 to 3,000 cases of plague every year.

SOURCE: CDC


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