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Related to plague: black plague, pneumonic plague


plague, any contagious, malignant, epidemic disease, in particular the bubonic plague and the black plague (or Black Death), both forms of the same infection. These acute febrile diseases are caused by Yersinia pestis (Pasteurella pestis), discovered independently by Shibasaburo Kitasato and Alexandre Yersin in 1894, a bacterium that typically is transmitted to people by fleas from rodents, in which epidemic waves of infection always precede great epidemics in human populations. People may also contract the disease through direct contact with infected animals and persons, and from fleas and lice from infected persons. When the disease occurs in rodents or other wild mammals in rural or wooded areas where they are prevalent, it is known as sylvatic plague; when it occurs in urban animal populations, typically rats, it is called urban plague.

Bubonic plague, the most common form, is characterized by very high fever, chills, prostration, delirium, hemorrhaging of the small capillaries under the skin, and enlarged, painful lymph nodes (buboes), which suppurate and may discharge. Invasion of the lungs by the organism (pneumonic plague) may occur as a complication of the bubonic form or as a primary infection. Pneumonic plague is rapidly fatal and is spread from person to person (by droplet spray) without intermediary transmission by fleas. In the black form of plague, hemorrhages turn black, giving the term “Black Death” to the disease. An overwhelming infection of the blood may cause death in three or four days, even before other symptoms appear.

In untreated cases of bubonic plague the mortality rate is approximately 50%–60%; pneumonic plague is usually fatal if not treated within 24 hours. Such antibiotics as streptomycin and tetracycline greatly reduce the mortality rate, especially of bubonic plague. Vaccine is available for preventive purposes. Rodent control is important in areas of known infection.


The oldest known evidence of the plague was identified in DNA collected from a woman buried in Sweden some 5,000 years ago. The earliest recorded visitation of the plague to Europe may have occurred in Athens in 430 B.C., but it is unclear if the disease that afflicated Athens was caused by Y. pestis. A epidemic occurred in the Mediterranean during the time of the Roman emperor Justinian, but more recent research has challenged the long-standing belief that 25% to 50% of the population succumbed. The most widespread epidemic began in Constantinople in 1334, spread throughout Europe (returning Crusaders were a factor), and in less than 20 years is estimated to have killed three quarters of the population of Europe and Asia. The great plague of London in 1665 is recorded in many works of literature. Quarantine measures helped contain the disease, but serious epidemics continued to occur even in the 19th cent. The disease is still prevalent in parts of Asia, and sporadically occurs elsewhere (approximately 2,500 cases worldwide annually). In Surat, India, in 1994, 5,000 cases of pneumonic plague were reported in an outbreak; an estimated 100 people died, and more than 400,000 people fled the city. Because the number of cases of plague has been increasing annually, it is categorized as a re-emerging infectious disease by the World Health Organization.


See P. Ziegler, The Black Death (1969); W. Whitman, Travel in Turkey, Asia Minor, Syria and Egypt (1971); R. S. Gottfried, The Black Death (1983); G. Twigg, The Black Death: A Biological Reappraisal (1985); R. Horrox, ed., The Black Death (1994); O. J. Benedictow, The Black Death 1346–1353: The Complete History (2004); W. Orent, Plague (2004); J. Aberth, The Black Death: The Great Mortality of 1348–1350 (2005); J. Kelly, The Great Mortality: An Intimate History of the Black Death (2005).

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An infectious disease of humans and rodents caused by the bacterium Yersinia pestis. The sylvatic (wild-animal) form persists today in more than 200 species of rodents throughout the world. The explosive urban epidemics of the Middle Ages, known as the Black Death, resulted when the infection of dense populations of city rats living closely with humans introduced disease from the Near East. The disease then was spread both by rat fleas and by transmission between humans. During these outbreaks, as much as 50% of the European population died. At present, contact with wild rodents and their fleas, sometimes via domestic cats and dogs, leads to sporadic human disease. See Infectious disease

After infection by Y. pestis, fleas develop obstruction of the foregut, causing regurgitation of plague bacilli during the next blood meal. The rat flea, Xenopsylla cheopsis, is an especially efficient plague vector, both between rats and from rats to humans. Human (bubonic) plague is transmitted by the bite of an infected flea; after several days, a painful swelling (the bubo) of local lymph nodes occurs. Bacteria can then spread to other organ systems, especially the lung; fever, chills, prostration, and death may occur. Plague pneumonia develops in 10–20% of all bubonic infections. In some individuals, the skin may develop hemorrhages and necrosis (tissue death), probably the origin of the ancient name, the Black Death. The last primary pneumonic plague outbreak in the United States occurred in 1919, when 13 cases resulting in 12 deaths developed before the disease was recognized and halted by isolation of cases.

Bubonic plaque is suspected when the characteristic painful, swollen glands develop in the groin, armpit, or neck of an individual who has possibly been exposed to wild-animal fleas in an area where the disease is endemic. Immediate identification is possible by microscopic evaluation of bubo aspirate stained with fluorescent-tagged antibody. Antibiotics should be given if plague is suspected or confirmed. Such treatment is very effective if started early. The current overall death rate, approximately 15%, is reduced to less than 5% among patients treated at the onset of symptoms. See Immunofluorescence, Medical bacteriology

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an acute infectious disease of man and animals, classified as a quarantine disease. The causative agent is the plague bacillus, Pasteurella pestis, discovered in 1894 by the French scientist A. Yersin (1863–1943) and the Japanese scientist Kitasato Shibasaburo (1852–1931). It is a coccoid gram-negative bacillus that grows well on ordinary culture media and is sensitive to physical and chemical factors, as well as to ordinary disinfectants. It dies within one minute of exposure to a temperature of 100°C.

Plague epidemics periodically swept many countries. The first pandemic, known in the literature as Justinian’s plague, occurred in the sixth century in the Eastern Roman Empire, affecting many countries and killing about 100 million persons in 50 years. The second pandemic, known as the Black Death, began in the 14th century. The third, which broke out at the end of the 19th century, was spread by ship rats to more than 100 ports in various countries. Occurrences of plague were recorded from the 14th century on in central and northwestern Russia, including numerous occurrences in Moscow. It occurred in Transbaikalia, Transcaucasia, and the Caspian Region in the 19th century and in Odessa and other Black Sea ports at the end of the 19th and early 20th centuries, where it was brought in by plague-infected rats. Major epidemics were recorded in India in the 20th century.

Plague is characterized by natural endemism, associated with desert, steppe, and mountain landscapes, where the epizootic process is maintained by certain rodent species; however, other rodents, as well as hares, camels, and other mammals, are also dangerous to man. The epidemiological danger increases when plague is introduced into populations of commensal rodents, such as rats. The disease is transmitted to humans by animals through fleas; less common is infection as a result of direct contact, usually contracted when dressing the carcasses of infected animals. Humans infect other humans through fleas. When the bubonic form is complicated by pneumonia (secondary pneumonic plague), the disease is spread by airborne droplets, like influenza, and the highly contagious primary pneumonic plague occurs. Depending on the mechanism of infection, the causative agent penetrates the organism through the skin, the mucosa of the upper respiratory tract, and the conjunctiva. Carriers of the plague bacillus (in the nasopharynx) have been discovered.

The incubation period of plague is two to six days. The disease is characterized by sudden onset, chills, severe headache, agitation, and mental confusion. The body temperature rises to 40°C, and hyperemia of the face is observed. Frequently, the meninges become involved. In the bubonic form painful buboes appear on different parts of the body; symptoms of pneumonia appear in the pneumonic form. The course is generally severe. Bacteriological and serological methods are used for laboratory diagnosis.

Treatment includes the administration of streptomycin and other antibiotics. Preventive measures include epidemiological reconnaissance in areas where the disease is endemic (epizootological survey and observation of human and animal populations) and the use of live vaccines. To achieve early and emergency prophylaxis, the extermination of rodents and fleas in the wild and in dwellings is vital. In the event of an epidemic, infected persons are hospitalized, and individuals who have come in contact with them are isolated and given prophylactic treatment. Disinfection and quarantine measures are also instituted.


Nikolaev, N. I. Chuma. Moscow, 1968.
Obshchaia i chastnaia epidemiologiia, vol. 2. Moscow, 1973. Pages 337–356.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


An infectious bacterial disease of rodents and humans caused by Pasteurella pestis, transmitted to humans by the bite of an infected flea (Xenopsylla cheopis) or by inhalation. Also known as black death; bubonic plague.
Any contagious, malignant, epidemic disease.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. any widespread and usually highly contagious disease with a high fatality rate
2. an infectious disease of rodents, esp rats, transmitted to man by the bite of the rat flea (Xenopsylla cheopis)
4. a pestilence, affliction, or calamity on a large scale, esp when regarded as sent by God
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Plague is transmitted to humans via flea bites, handling of an infected animal or through the air in close quarters when a plague-infected person coughs (the CDC says the latter hasn't happened in the United States since 1924).
In Madagascar, per the Plague National Control Program (PNCP), reporting of suspected human cases by health centers is mandatory.
Chiu presents two ways in which musical works connected to the plague: pieces written in response to the disease, and those employed in penitential processions.
Human symptoms of plague usually appear within two to six days of contracting the disease.
For most people, "the plague" conjures up images of the medieval Black Death, and perhaps a vaguely reassuring sense that, in the developed world, such ancient dangers are long past.
Plague is common in Madagascar, since the streets are crowded and unsanitary, causing diseases to spread easily.
The Bible allows for the possibility that the tenth plague was a syndemic resulting from earlier plagues.
WHO reported between 1989 and 2003 a total of 38,310 notified human plague cases, with 2,845 deaths, from 25 countries, with the highest number of human plague cases being notified in 1991 and the lowest number being reported in 1989.
This new Canadian plague patent, which has been assigned the serial number 2692933, is entitled "Yersinia Pestis Antigens, Vaccine Compositions and Related Methods".
In 1636, the town - it wasn't a city yet - was a busy sea port and the plague is thought to have arrived, via North Shields, at the poverty-stricken Sandhill area of the Quayside before quickly spreading.
This exciting second book in A Blackthorn Key Adventure series begins as the black plague returns to London.