Bubonic plague

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Image:Yersinia pestis fluorescent.jpeg

Bubonic plague is the most well-known variant of the deadly infectious disease plague, which is caused by the enterobacteria Yersinia pestis. Plague has impacted human society for millennia. Most scientists believe that it was responsible for the Black Death, which killed perhaps a third of Europe's population during the Middle Ages, with additional large numbers of casualties in Asia and the Middle East.

Plague is endemic in many countries in Africa, in the former Soviet Union, the Americas and Asia. In 2003, nine countries reported 2,118 cases to the WHO, whereof 182 ended with death. All were isolated cases, except for an outbreak in a village in Algeria (the first in 50 years), which caused 11 infections and one death. Plague is most common in Madagascar and the Democratic Republic of the Congo. These two countries have on average 600-800 cases each per year. They accounted for 2,025 of the 2,118 cases and 177 of the 182 deaths in 2003. Other countries with annual but much fewer cases are Tanzania, Peru, United States, China, Mongolia and Vietnam. According to the WHO, the actual number of cases in the world is probably much higher than reported, due to the reluctance of certain endemic countries to declare cases, the lack of diagnosis because the clinical picture of cases is not very specific, and the absence of laboratory confirmation.

The most recent outbreak of plague happened in Zobia, in the northern part of the Democratic Republic of the Congo in December 2004. The outbreak, which only appeared as the variant pneumonic plague, began among workers in a diamond mine. By mid March 2005 the WHO regarded the outbreak as over. 130 people had been infected, whereof 57 died. [1]

There has not been a plague epidemic (i.e an outbreak affecting a larger area) for many years.

Contents

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Infection/transportation

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 bacteria multiply inside a flea, blocking its stomach and causing it to become very hungry. The flea then voraciously bites a host and continues to feed because it is unable to satisfy its hunger. During the feeding process, infected blood carrying the plague bacteria flows into the wound. The plague bacteria then has a new host, and the flea eventually dies from starvation. 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, two bacteriologists, the Swiss Alexandre Yersin and the Japanese Shibasaburo Kitasato, independently isolated the responsible bacterium in Hong Kong during the Third Pandemic. Though both investigators reported their findings, there were a series of confusing and contradictory statements by Kitasato that eventually led to the acceptance of Yersin as the primary discoverer of the organism. Yersin named it Pasteurella pestis in honour of the Pasteur Institute, where he worked, but in 1967 it was renamed Yersinia pestis in honour of Yersin. Yersin also noted that rats were affected by plague, not only during plague epidemics but also often preceding such epidemics in humans, and that plague was regarded by many locals as a disease of the rats: villagers in China and India described that when large numbers of rats were found dead, plague outbreaks in people soon followed.

In 1898, the French scientist Paul-Louis Simond (who had also come to China to battle the Third Pandemic) established the the rat-flea mechanism that drives the disease. He had noted that persons who became ill did not have to be in close contact with each other to acquire the disease. In Yunnan, China, inhabitants would run away from their homes as soon as they saw dead rats, and on the island of Formosa (Taiwan), residents considered handling dead rats a risk for developing plague. These observations led him to suspect that the flea might be an intermediary factor in the transmission of plague, since people acquired plague only if they were in contact with recently dead rats, but not affected if they touched rats that had been dead for more than 24 hours. In a now classic experiment, Simond demonstrated how a healthy rat died of plague after infected fleas had jumped to it from a plague-dead rat.

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Types

Depending on the symptoms and the route of infection, plague appears in several forms, classified by the WHO with different ICD-10 codes:

Main disease:
(A20) Plague (Pestis). Infections caused by Yersinia pestis.
Forms:
(A20.0) Bubonic plague (Pestis bubonica) occurs when Yersinia pestis causes an inflammation of the lymph nodes, making them tender and swollen (from lat. bubo = bump). This is the most common form of plague.
(A20.1) Cellulocutaneous plague (Pestis cellulocutanea) is a very unusual form, with Yersinia pestis causing a skin infection.
(A20.2) Pneumonic plague or pulmonic plague (Pestis pneumonica) occurs when the lungs are infected by Yersinia pestis. The second most common form of plague. Is may be a secondary infection, caused by bacteria spreading from the lymph nodes and reaching the lungs, but can also exist on its own, caused by inhalation of airborne bacteria.
(A20.3) Meningeal plague or plague meningitis (Pestis meningealis) looks like meningitis at the outset. It is most common in children and is usually the end result of ineffective treatment for other forms of plague. Unusual.
(A20.?) Pharyngeal plague occurs when Yersinia pestis is consumed, often through food. It can resemble tonsillitis. Very rare form.
(A20.7) Septicemic plague (Pestis septic(h)aemica) occurs when Yersinia pestis multiply in the blood. The third most common form. It is usually associated with hunting and skinning of animals, but can also occur secondary to bubonic and pneumonic plague.
(A20.8) Other forms of plague (Aliae formae pestis) include the milder forms abortive plague, asymptomatic plague and pestis minor, all three often resulting only in a mild fever and light swelling of the lymph glands, usually resolved in approximately a week if appropriate treatment is given.
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Clinical features

Bubonic plague becomes evident 3–7 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 30–75%.

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 reduces the mortality rate to 4 to 15%.<ref name="Wagle1948">{{cite journal | author=Wagle PM | title=Recent advances in the treatment of bubonic plague | journal=Indian J Med Sci | year=1948 | volume=2 | pages=489–94 }}</ref><ref name="Meyer1950">{{cite journal | author=Meyer KF | title=Modern therapy of plague | year=1950 | journal=J Am Med Assoc | volume=144 | pages=982–5 }}</ref><ref name="DattGupta1948">{{cite journal | author=Datt Gupta AK | title=A short note on plague cases treated at Campbell Hospital | journal=Ind Med Gaz | year=1948 | volume=83 | pages=150–1 }}</ref> 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%.

Image:Doktorschnabel 430px.jpg

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Treatment

The traditional treatments are:

  • Streptomycin 30mg/kg IM twice daily for 7 days
  • Chloramphenicol 25–30mg/kg single dose, followed by 12.5–15mg/kg four times daily
  • Tetracycline 2g single dose, followed by 500mg four times daily for 7–10 days (not suitable for children)

More recently,

have also been shown to be effective.<ref name="Mwengee2006">{{cite journal | author=Mwengee W et al. | title=Treatment of Plague with Genamicin or Doxycycline in a Randomized Clinical Trial in Tanzania | year=2006 | journal=Clin Infect Dis | volume=42 | issue=5 | pages=614–21 }}</ref>

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History

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Historical plague epidemics

The earliest account, familiar to the West, describing a possible outbreak of plague is found in the book of I Samuel 5:6 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 possibly one-third of its population, including Pericles (Speilvogal, J, 1999, pp. 56). The loss of population did not affect the progress and outcome of the war. This epidemic has long been considered an outbreak of plague. However, from Thucydides' description, more modern scholars dispute the assignment of plague, feeling that smallpox or measles may be better candidates. A recent study of the DNA found in the dental pulp of plague victims suggests that typhoid was responsible for the epidemic.Template:Note Other scientists dispute the findings, citing serious methodologic flaws in the DNA study.

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 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 marmot, a small rodent 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.

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.

During the mid-14th century, the Black Death, a massive and deadly epidemic, swept through Eurasia, killing approximately one-third of the population (according to some estimates) and changing the course of Asian and European history. The 237 million victims (approx), throughout the many years of infection, constituted the largest death toll from any known epidemic. Many scientists and historians believe the Black Death was an incidence of plague, with a strong presence of the more contagious pneumonic and septicemic varieties increasing 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 not returned to Europe; however, changes in hygiene habits and strong efforts within public health and sanitation probably had a significant impact on the rate of infection from the infectious disease.

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Third Pandemic

For more complete information see Third Pandemic.

The Third Pandemic began in China in 1855, spreading 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 bacterium, 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, such as cows or horses, and human 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 bacterium. 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 bactrium, developing strains resistant to antibiotics, combining the bacterium 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 bacteria were produced. Information on many of the Soviet projects is largely unavailable. Aerosolized pneumonic plague remains the most significant threat.

Image:World distribution of plague 1998.PNG

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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.

On 2005-09-15, ABC News reported[2] that three mice infected with Yersinia pestis apparently disappeared from a laboratory belonging to the Public Health Research Institute, located on the campus of the University of Medicine and Dentistry of New Jersey, which conducts anti-bioterrorism research for the United States government.

On 2006-04-19, CNN News and others reported a case of plague in Los Angeles, California, the first reported case in that city since 1984.

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Uses in literature

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References

  • Biraben, Jean-Noel. Les Hommes et la Peste The Hague 1975.
  • Cantor, Norman F., In the Wake of the Plague: the Black death and the World It Made New York: Harper 2001.
  • 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. Reprinted with new preface 1998.
  • 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.
  • Platt, Colin. King Death: The Black Death and its Aftermath in Late-Medieval England Toronto University Press, 1997.
  • 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.
  • ABC News, Plague Infected Mice Missing From N.J. Lab, 2005-09-15
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Numbered references

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See also

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External links

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