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Bubonic plague is an infectious disease that is believed to have caused several epidemics or pandemics throughout history. Bubonic plague is the most common form of plague which causes swollen, tender lymph glands (called buboes); other forms are Septicemic plague which occurs when plague bacteria multiply in the blood and Pneumonic plague which occurs when the lungs are infected.
It is primarily a disease of rodents, particularly marmots (in which the most virulent strains of plague are primarily found), but also black rats, prairie dogs, chipmunks, squirrels and other similar large rodents. HumanHuman beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. Biologically, they are classified as Homo sapiens ( Latin for knowing man , a primate species of mammal with a highly developed brain. In spiritua infection occurs when people come into contact with infected rodents.
The disease is caused by the bacterium Yersinia pestisYersinia pestis is a species of gram-negative coccobacillus (i. rod-shaped bacterium) in the family Enterobacteriaceae, genus Yersinia; it is the infectious agent of bubonic plague. This organism can also cause pneumonic plague and septicemic plague. and is usually transmitted by the biteA bite is a wound received from the mouth of an animal. Bite wounds raise a number of issues from the viewpoint of medicine in addition to the physical wounds they leave, including the possibility of: poison infection by bacteria or other pathogens; and r of fleaFor the musician, a member of the Red Hot Chili Peppers, see Michael Balzary. Tungidae Sticktight and Chigoe fleas Pulicidae Common fleas Coptopsyllidae Vermipsyllidae Carnivore fleas Rhopalopsyllidae Marsupial fleas Hypsophthalmidae Stephanocircidae Pygis from an infected host, often a black rat. The bacteria are transferred from the blood of infected rats to the rat flea (Xenopsylla cheopsis). The bacillus multiplies in the stomach of the flea, blocking it. When the flea next bites a mammal, the consumed blood is regurgitated along with the bacillus into the bloodstream of the bitten animal. Any serious outbreak of plague is started by other disease outbreaks in the rodent population. During these outbreaks, infected fleas that have lost their normal hosts seek other sources of blood.
The disease becomes evident 2-7 days after infection. Initial symptoms are chills, fever, headaches, and the formation of buboes. The buboes are formed by the infection of the lymph nodes, which swell and become prominent. If unchecked, the bacteria infect the bloodstream (septicemic plague) and then the lungs (pneumonic plague).
In septicemic plague there is bleeding into the skin and other organs, which creates black patches on the skin, hence the name Black Death. Untreated septicemic plague is universally fatal, but early treatment with antibiotics is effective (usually streptomycin or gentamicin), reducing the mortality rate to around 15% (USA 1980s). People who die from this form of plague often die on the same day that symptoms first appear.
With pneumonic plague the infected lungs raised the possibility of person-to-person transmission through respiratory droplets. The incubation period for pneumonic plague is usually between two to four days, but can be as little as a few hours. The initial symptoms of headache, weakness, and coughing with hemoptysis are indistinguishable from other respiratory illnesses. Without diagnosis and treatment the infection can be fatal in one to six days; mortality in untreated cases may be as high as 95%. The disease can be effectively treated with antibiotics, however.
As a biological weapon aerosolized pneumonic plague is the only modernly credible plague agent. However, historical accounts detail the use of infected animal carcasses to infect enemy water supplies in medieval Europe. In addition, experiments (both in the lab and the field) using the release of infected rats on the ground, and the release of infected fleas, by both aerial drop and modified explosives, have been alledged to have been conducted as recently as in the first half of the 20th century.
"Doktor Schnabel von Rom" (English: "Doctor Beak from Rome") engraving by Paul Fürst (after J Columbina). The beak is a primitive gas mask, stuffed with substances thought to ward off the plague.
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