Bubonic plague

Categories: Infectious diseases | Epidemics | Pandemics | Biological weapons

Bubonic plague
ICD-10 code:	A20.0
ICD-9 code:	020.0

Bubonic plague is an infectious disease that is believed to have caused several epidemics or pandemics throughout history. The disease is caused by the bacterium Yersinia pestis. Bubonic plague is the most common form of plague, and is characterized by swollen, tender, inflamed 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.

1 Infection/transportation
2 Symptoms and treatment
3 Historical epidemics
4 Historical pandemics
5 Plague as a biological weapon
6 Contemporary cases
7 References
8 In literature
9 See also
10 External links

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Infection/transportation

Bubonic plague 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. Human infection most often occurs when a person is bitten by a rat flea (Xenopsylla cheopsis) that has fed on an infected rodent. The bacillus multiplies in the stomach of the flea, blocking it. When the flea next bites a mammal, blood consumed by the flea 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.

In 1894, bacteriologists Alexandre Yersin and Shibasaburo Kitasato independently isolated the responsible bacterium and Yersin further determined that rodents were the likely common mode of transmission. The disease is caused by the bacterium Yersinia pestis.

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Symptoms and treatment

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 infects the bloodstream (septicemic plague), and can progress to the lungs (pneumonic plague).

In septicemic plague there is bleeding into the skin and other organs, which creates black patches on the skin. Untreated septicemic plague is universally fatal, but early treatment with antibiotics (usually streptomycin or gentamicin) is effective, reducing the mortality rate to around 15% (USA 1980s). People who die from this form of plague often die on the same day symptoms first appear.

With pneumonic plague infecting lungs comes the possibility of person-to-person transmission through respiratory droplets. The incubation period for pneumonic plague is usually between two and 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.

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Historical epidemics

The first Western literary account of a possible outbreak of plague is found in the book of Samuel V of the Hebrew Bible. In this account, the Philistines of Ashdod were struck with a plague for the crime of stealing the Ark of the Covenant from the Children of Israel. These events have been dated to approximately the second half of the eleventh century B.C. The word "hemorrhoids" is used in English translations to describe the sores that came upon the Philistines. The Hebrew, however, can be interpreted as "swelling in the secret parts". The account indicates that the Philistine city and its political territory were struck with a "ravaging of mice" and a plague, bringing death to a large segment of the population.

In the second year of the Peloponnesian War (430 B.C.), Thucydides described the coming of an epidemic disease which began in Ethiopia, passed through Egypt and Libya, and then came to the Greek world. Athens was decimated by this plague, losing a possible third of its populace, including Pericles (Speilvogal, J, 1999, pp. 56). In spite of the loss in population, this did not affect the progress and outcome of the war. This epidemic has long been considered an outbreak of bubonic plague. However, from Thucydides' description, some modern scholars dispute the assignment of plague, feeling that smallpox or measles may be better candidates.

In the first century AD, Rufus of Ephesus, a Greek anatomist, refers to an outbreak of plague in Libya, Egypt, and Syria. He records that Alexandrian doctors named Dioscorides and Posidonius described symptoms including acute fever, pain, agitation, and delirium. Buboes—large, hard, and non-suppurating—developed behind the knees, around the elbows, and "in the usual places." The death toll of those infected was very high. Rufus also wrote that similar buboes were reported by a Dionysius Curtus, who may have practiced medicine in Alexandria in the third century B.C. If this is correct, the eastern Mediterranean world may have been familiar with bubonic plague at that early date. (ref. Simpson, W.J., Patrick, A.)

The last significant European outbreak of bubonic plague occurred in Russia in A.D. 1877–1889 in rural areas near the Ural Mountains and the Caspian Sea. This outbreak is sometimes seen as an extension of the Third Pandemic (see below). Efforts in hygiene and patient isolation reduced the spread of the disease, with approximately 420 deaths in the region. Significantly, the region of Vetlianka in this area is near a population of the "bobak", a type of small marmot considered a very dangerous plague reservoir.

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Historical pandemics

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Plague of Justinian

For more complete information, see Plague of Justinian.

See also Climate changes of 535-536.

The Plague of Justinian is the first known pandemic on record, and marks the first firmly recorded pattern of bubonic plague in A.D. 541–542. This outbreak is thought to have originated in Ethiopia or Egypt. The huge city of Constantinople imported massive amounts of grain, mostly from Egypt, to feed its citizens. The grain ships may have been the source of contagion for the city, with massive public granaries nurturing the rat and flea population. At its peak the plague was killing 5,000 people in Constantinople every day and ultimately destroyed perhaps 40 percent of the city's inhabitants. It went on to destroy up to a quarter of the human population of the eastern Mediterranean.

In A.D. 588 a second major plague wave spread through the Mediterranean into what is now France. A maximum of 25 million dead is considered a reasonable estimate.

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Black Death

For more complete information, see Black Death.

Image:Doktorschnabel 430px.jpg

"Doctor Schnabel von Rom" (English: "Doctor Beak of Rome") engraving by Paul Fürst (after J Columbina). The beak is a primitive gas mask, stuffed with substances (such as spices and herbs) thought to ward off the plague.

During the mid-14th century, the Black Death, a massive and deadly epidemic, swept through Eurasia, killing one-third of the population (according to some estimates) and changing the course of Asian and European history. The 200 million victims constituted the largest death toll from any known epidemic of any disease. Many scientists and historians believe the Black Death was an incidence of bubonic plague. A strong presence of the more contagious pneumonic and septicemic varieties increased the pace of infection, spreading the disease deep into inland areas of the continents.

Plague continued to strike parts of Europe throughout the 15th century, the 16th century and the 17th century with varying degrees of intensity and fatality. Researchers still do not agree on why large outbreaks of the infection have never returned to Europe. However, changes in hygiene habits and strong efforts toward public health and sanitation probably had a significant impact on the survival of the disease.

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Third Pandemic

For more complete information see Third Pandemic.

The Third Pandemic began in China in 1855, spreading the bubonic plague to all inhabited continents, and ultimately killing more than 12 million people in India and China alone. Casualty patterns indicate that waves of this pandemic may have been from two different sources. The first was primarily bubonic and was carried around the world through ocean-going trade, transporting infected persons, rats, and cargos harboring fleas. The second, more virulent strain was primarily pneumonic in character, with a strong person-to-person contagion. This strain was largely confined to Manchuria and Mongolia. Researchers during the "Third Pandemic" identified plague vectors and the plague bacillus, leading in time to modern treatment methods.

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Plague as a biological weapon

Plague has a long history as a biological weapon. Historical accounts from medieval Europe detail the use of infected animal carcasses, by Mongols, Turks and other groups, to contaminate enemy water supplies. Plague victims were also reported to have been tossed by catapult into cities under siege.

During World War II, the Japanese Army developed weaponized plague based on the breeding and release of large numbers of fleas. During the Japanese occupation of Manchuria, Unit 731 deliberately infected civilians and prisoners of war with the plague bacillus. These subjects, called "logs", were then studied by dissection, some while still living and conscious. After World War II, both the United States and the Soviet Union developed means of weaponizing pneumonic plague. Experiments included various delivery methods, vacuum drying, sizing the bacillus, developing strains resistant to antibiotics, combining the bacillus with other diseases, such as diphtheria, and genetic engineering. Scientists who worked in USSR bio-weapons programs have stated that the Soviet effort was formidable and that large stocks of weaponized plague bacillus were produced. Information on many of the Soviet projects is largely unavailable. Aerosolized pneumonic plague remains the most significant threat.[1][2]

Image:World distribution of plague 1998.PNG

Worldwide distribution of plague infected animals 1998

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Contemporary cases

The disease still exists in wild animal populations from the Caucasus Mountains east across southern and central Russia, to Kazakhstan, Mongolia, and parts of China; in Southwest and Southeast Asia, Southern and East Africa (including the island of Madagascar); in North America, from the Pacific Coast eastward to the western Great Plains, and from British Columbia south to Mexico; and in South America in two areas: the Andes mountains and Brazil. There is no plague-infected animal population in Europe or Australia.

Globally, the World Health Organization reports 1,000 to 3,000 human cases of plague every year.

In September 2005 the Associated Press reported that three mice infected with the bacteria responsible for bubonic plague apparently disappeared from a laboratory. The mice were unaccounted-for at the Public Health Research Institute, which is on the campus of the University of Medicine and Dentistry of New Jersey and conducts bioterrorism research for the United States federal government.

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References

de Carvalho, Raimundo Wilson; Serra-Freire, Nicolau Maués; Linardi, Pedro Marcos; de Almeida, Adilson Benedito; and da Costa, Jeronimo Nunes (2001). Small Rodents Fleas from the Bubonic Plague Focus Located in the Serra dos Órgãos Mountain Range, State of Rio de Janeiro, Brazil. Memórias do Instituto Oswaldo Cruz 96(5), 603–609. PMID 11500756. this manuscript reports a census of potential plague vectors (rodents and fleas) in a Brazilian focus region (i.e. region associated with cases of disease); free PDF download Retrieved 2005-03-02
Gregg, Charles T. Plague!: The shocking story of a dread disease in America today. New York, NY: Scribner, 1978, ISBN 0684153726.
Kelly, John. The Great Mortality: An Intimate History of the Black Death, the Most Devastating Plague of All Time. New York: HarperCollins Publishers Inc., 2005. ISBN 0060006927.
McNeill, William H. Plagues and People. New York: Anchor Books, 1976. ISBN 0385121229.
Orent, Wendy. Plague: The Mysterious Past and Terrifying Future of the World's Most Dangerous Disease. New York: Free Press, 2004. ISBN 0743236858.
Patrick, Adam. "Disease in Antiquity: Ancient Greece and Rome," in Diseases in Antiquity, editors: Don Brothwell and A. T. Sandison. Springfield, Illinois; Charles C. Thomas, 1967.
Simpson, W. J. A Treatise on Plague. Cambridge, England: Cambridge University Press, 1905.
Speilvogal, Jackson J. Western Civilization: A Brief History Vol. 1: to 1715. Belmont, Calif.: West/Wadsworth, 1999, Ch. 3, p. 56, paragraph 2. ISBN 0534560628.

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In literature

The Decameron by Giovanni Boccaccio (1350). Takes place in Florence in 1348, during the outbreak of the "Black Death", widely believed to be Bubonic Plague.
The Plague by Albert Camus (1947). An existentialist novel centered around an outbreak of the plague.
A Journal of the Plague Year by Daniel Defoe (1722). A fictional first hand account of the London outbreak of 1665.
Doomsday Book by Connie Willis (1992). A Hugo award and Nebula award-winning historical science fiction novel, in which a time-traveler inadvertently ends up in the plague-ridden England of 1348.