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Bubonic plague

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 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.



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. Human infection most often occurs when a person is bitten by a flea that has previously fed on an infected rodent.

In 1896, bacteriologist Alexandre Yersin isolated the responsible bacterium and determined the common mode of transmission. The disease is caused by the bacterium Yersinia pestis and is usually transmitted by the bite of fleas 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.

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), which 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, 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 infecting lungs came 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.

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 which 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 was struck with both 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 the populace, including Pericles (Speilvogal, J, 1999, pp. 56). This, in spite the loss in population, had no consequent effect on 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 which included 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 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.

Historical pandemics

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 it also marks the first firmly recorded pattern of bubonic plague in A.D. 541–542. This outbreak may have originated in Ethiopia or Egypt. The huge city of Constantinople imported massive amounts of grain to feed its citizens, mostly from Egypt. The grain ships may have been the original 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 killed 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.

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

Black Death

For more complete information, see Black Death.
"Doktor Schnabel von Rom" (English: "Doctor Beak from Rome") engraving by Paul Fürst (after J Columbina). The beak is a primitive , stuffed with substances thought to ward off the plague.
"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.

During the mid-1300s, the Black Death, a massive and deadly epidemic swept through Eurasia, killing one-third of the population by some estimates, and subsequently changing the course of both Asian and European history. The 200 million people who died was the largest death toll from any known epidemic of any disease. Many scientists and historians believe that this outbreak was an incidence of bubonic plague. A strong presence of the more contagious pneumonic and septicemic varieties increased the pace of infection and led to the spread of the disease deep into the inland areas of the continents.

Plague continued to strike parts of Europe throughout the 1400s, 1500s and 1600s 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.

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, through 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.

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 infect 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, civilians and prisoners of war were deliberately infected 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 diptheria, 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]

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); and 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.


  • 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.

In literature

See also

External links

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