Disease Information for Plague, bubonic: Definition

Bubonic plague is the best-known variant of the deadly infectious disease plague, which is caused by the enterobacteria Yersinia pestis; The epidemiological use of the term plague is currently applied to bacterial infections that cause buboes, although historically the medical use of the term plague has been applied to pandemic infections generally; Plague is primarily a disease of rodents and fleas; Infection most often occurs when a person is bitten by an infected rodent which has been infected by a flea; The bacteria multiply inside the flea, sticking together to form a plug that blocks its stomach and causes it to begin to starve; The flea then voraciously bites a host and continues to feed, even though it is unable to satisfy its hunger; During the feeding process, blood cannot flow into the blocked stomach, and consequently the flea vomits blood tainted with the bacteria back into the bite wound; The Bubonic plague bacterium then infects a new host, and the flea eventually dies from starvation; Any serious outbreak of plague is usually started by other disease outbreaks in rodents, or some other crash in the rodent population; During these outbreaks, infected fleas that have lost their normal hosts seek other sources of blood; Bubonic plague becomes evident three to eight days after the infection; Initial symptoms are chills, fever, diarrhea, headaches, and the swelling of the infected lymph nodes, as the bacteria replicate there; If untreated, the rate of mortality for bubonic plague is 50-90%; In septicemic plague, there is bleeding into the skin and other organs, which creates black patches on the skin. There are bite-like bumps on the skin, commonly red and sometimes white in the center; Untreated septicemic plague is universally fatal, but early treatment with antibiotics reduces the mortality rate to between 4 and 15 percent; People who die from this form of plague often die on the same day symptoms first appear

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