Tuesday, February 16, 2010

The Black Death

The Black Death was one of the deadliest pandemics in human history, peaking in Europe between 1348 and 1350. It is widely thought to have been an outbreak of bubonic plague caused by the bacterium Yersinia pestis, but this view has recently been challenged. Usually thought to have started in Central Asia, it had reached the Crimea by 1346. From there, probably carried by fleas residing on the black rats that were regular passengers on merchant ships, it spread throughout the Mediterranean and Europe.

The Black Death is estimated to have killed 30% to 60% of Europe's population, reducing the world's population from an estimated 450 million to between 350 and 375 million in 1400. This has been seen as creating a series of religious, social and economic upheavals which had profound effects on the course of European history. It took 150 years for Europe's population to recover. The plague returned at various times, resulting in a larger number of deaths, until it left Europe in the 19th century.


The Black Death is categorized into three specific types of plague: bubonic plague (infection in the lymph nodes, or [hence] buboes), pneumonic plague (the infection in the lungs), and septicemic plague (the infection in the blood and the most deadly of the three). Scientists and historians at the beginning of the 20th century assumed that the Black Death was an outbreak of the same diseases, caused by the bacterium Yersinia pestis and spread by fleas which primarily made use of highly mobile small animal populations like that of the black rat (Rattus rattus). Once infected by the Yersinia pestis bacterium, it is estimated that victims would die within three to seven days.[1] However, this view has recently been questioned by some scientists and historians,[2] and some researchers, examining historical records of the spread of disease,[3][4] believe that the illness was, in fact, a viral hemorrhagic fever.

Some historians believe the pandemic began in China or Central Asia (one such location is Lake Issyk Kul)[5] in the lungs of the bobac variety of marmot, spreading to fleas, to rats, and eventually to humans.[6] In the late 1320s or 1330s, merchants and soldiers carried it over the caravan routes until in 1346 it reached the Crimea in South Eastern Europe. Other scholars believe the plague was endemic in that area. In either case, from Crimea the plague spread to Western Europe and North Africa during the 1340s.[7][8] The total number of deaths worldwide is estimated at 75 million people,[9] approximately 25–50 million of which occurred in Europe.[10][11] The Black Death is estimated to have killed 30% to 60% of Europe's population.[12][13][14] It may have reduced the world's population from an estimated 450 million to between 350 and 375 million in 1400.[15]

The plague is thought to have returned every generation with varying virulence and mortality until the 1700s.[16] During this period, more than 100 plague epidemics swept across Europe.[4] On its return in 1603, the plague killed 38,000 Londoners.[17] Other notable 17th-century outbreaks were the Italian Plague of 1629–1631, and the Great Plague of Seville (1647–1652), the Great Plague of London (1665–1666),[18] and the Great Plague of Vienna (1679). There is some controversy over the identity of the disease, but in its virulent form, after the Great Plague of Marseille in 1720–1722,[19] the Great Plague of 1738 (which hit eastern Europe), and the Russian plague of 1770-1772, it seems to have disappeared from Europe during the 19th century.

The 14th-century eruption of the Black Death had a drastic effect on Europe's population, irrevocably changing the social structure. It was, arguably, a serious blow to the Catholic Church, and resulted in widespread persecution of minorities such as Jews, foreigners, beggars, and lepers. The uncertainty of daily survival has been seen as creating a general mood of morbidity, influencing people to "live for the moment", as illustrated by Giovanni Boccaccio in The Decameron (1353).[20]


Medieval people called the catastrophe of the 14th century either the "Great Pestilence"' or the "Great Plague".[21] Writers contemporary to the plague referred to the event as the "Great Mortality". Swedish and Danish chronicles of the 16th century described the events as "black" for the first time, not to describe the late-stage sign of the disease, in which the sufferer's skin would blacken due to subepidermal hemorrhages (purpura), and the extremities would darken with gangrene (acral necrosis), as the term is more likely to refer to black in the sense of glum, lugubrious, or dreadful as to denote the terribleness and gloom of the events.[22] The German physician and medical writer Justus Hecker took that idea when he described the catastrophe in 1832[21] in his publication "Der schwarze Tod im vierzehnten Jahrhundert". The work was translated into English the following year, and under the influence of the cholera epidemic of that time, "The Black Death in the 14th century" gained widespread attention which coined the term Schwarzer Tod and Black Death in the German and English speaking worlds respectively.


The plague disease, generally thought to be caused by Yersinia pestis, is enzootic (commonly present) in populations of ground rodents (most specifically, the bobac variety of marmot)[23] in Central Asia, but it is not entirely clear where the 14th-century pandemic started. The popular theory places the first cases in the steppes of Central Asia, although some speculate that it originated around northern India, and others, such as the historian Michael W. Dols, argue that the historical evidence concerning epidemics in the Mediterranean and specifically the Plague of Justinian point to a probability that the Black Death originated in Africa and spread to Central Asia, where it then became entrenched among the rodent population.[24] Nevertheless, from Central Asia it was carried east and west along the Silk Road, by Mongol armies and traders making use of the opportunities of free passage within the Mongol Empire offered by the Pax Mongolica. It was reportedly first introduced to Europe at the trading city of Caffa in the Crimea in 1347. After a protracted siege, during which the Mongol army under Jani Beg was suffering the disease, they catapulted the infected corpses over the city walls to infect the inhabitants. The Genoese traders fled, taking the plague by ship into Sicily and the south of Europe, when it spread.[25] Whether or not this hypothesis is accurate, it is clear that several pre-existing conditions such as war, famine, and weather contributed to the severity of the Black Death. In China, the 13th century Mongol conquest disrupted farming and trading, and led to widespread famine. The population dropped from approximately 120 to 60 million.[26] The 14th-century plague is estimated to have killed one third of the population of China.[27]

In Europe, the Medieval Warm Period ended sometime towards the end of the 13th century, bringing the "Little Ice Age"[28] and harsher winters with reduced harvests. In the years 1315 to 1317 a catastrophic famine, known as the Great Famine, struck much of North West Europe. It has been argued that the famine came about as the result of a large population growth in the previous centuries, with the result that, in the early 14th century the population began to exceed the number that could be sustained by productive capacity of the land and farmers.[21]

In Northern Europe, new technological innovations such as the heavy plough and the three-field system were not as effective in clearing new fields for harvest as they were in the Mediterranean because the north had poor, clay-like, soil.[21] Food shortages and rapidly inflating prices were a fact of life for as much as a century before the plague. Wheat, oats, hay and consequently livestock, were all in short supply. Their scarcity resulted in malnutrition, which increases susceptibility to infections due to weakened immunity.

The European economy entered a vicious circle in which hunger and chronic, low-level debilitating disease reduced the productivity of labourers, and so the grain output was reduced, causing grain prices to increase. This situation was worsened when landowners and monarchs such as Edward III of England (r. 1327–1377) and Philip VI of France (r. 1328–1350), out of a fear that their comparatively high standard of living would decline, raised the fines and rents of their tenants.[21] Standards of living then fell drastically, diets grew more limited, and Europeans as a whole experienced more health problems.

In the autumn of 1314, heavy rains began to fall, which led to several years of cold and wet winters. The already weak harvests of the north suffered and the seven-year famine ensued. The Great Famine was arguably the worst in European history, perhaps reducing the population by more than 10%.[21] Records recreated from dendrochronological studies show a hiatus in building construction during the period, as well as a deterioration in climate.[29]

This was the economic and social situation in which the predictor of the coming disaster, a typhoid (contaminated water) epidemic, emerged. Many thousands died in populated urban centres, most significantly Ypres (now in Belgium). In 1318 a pestilence of unknown origin, sometimes identified as anthrax, targeted the animals of Europe, notably sheep and cattle, further reducing the food supply and income of the peasantry.


Bubonic infection

Several possible causes have been advanced for the Black Death; the most prevalent is the Bubonic plague theory[31] Efficient transmission of Y. pestis is generally thought to occur only through the bites of fleas whose mid guts become obstructed by replicating Y. pestis several days after feeding on an infected host. This blockage results in starvation and aggressive feeding behaviour by fleas that repeatedly attempt to clear their blockage by regurgitation, resulting in thousands of plague bacteria being flushed into the feeding site, infecting the host. However, modelling of epizootic plague observed in prairie dogs, suggests that occasional reservoirs of infection such as an infectious carcass, rather than "blocked fleas" are a better explanation for the observed epizootic behaviour of the disease in nature.[32]

One hypothesis about the epidemiology (the appearance, spread and especially disappearance) of plague from Europe, is that the flea-bearing rodent reservoir of disease was eventually succeeded by another species. The Black Rat (Rattus rattus) was originally introduced from Asia to Europe by trade, but was subsequently displaced and succeeded throughout Europe by the bigger Brown Rat (Rattus norvegicus). The brown rat was not as prone to transmit the germ-bearing fleas to humans in major outbreaks due to it occupying a different ecological niche.[33][34] The dynamic complexities of rat ecology, herd immunity in that reservoir, interaction with human ecology, secondary transmission routes between humans with or without fleas, human herd immunity and changes in each might explain the eruption, dissemination, and re-eruptions of plague that continued for centuries until its (even more) unexplained disappearance.

The persecution of cats in Europe is often overlooked as a contributing factor in the spread of plague. In years prior to the outbreak, cats had been vilified and slain en masse, due to their growing popular association with Satan and witches. Pope Gregory IX declared cats' association with the devil in the early 1200s. The mass slaughter of cats preceding the arrival of infected rats greatly reduced a potential predator of the rat, allowing rat populations to flourish unnaturally.[35]

Signs and symptoms

The three forms of plague brought an array of signs and symptoms to those infected. The septicemic plague is a form of "blood poisoning," and pneumonic plague is an airborne plague that attacks the lungs before the rest of the body. The classic sign of bubonic plague was the appearance of buboes in the groin, the neck and armpits, which oozed pus and bled. Most victims died within four to seven days after infection.

The bubonic plague was the most commonly seen form during the Black Death, with a mortality rate of thirty to seventy-five percent and symptoms including fever of 38–41 °C (101–105 °F), headaches, painful aching joints, nausea and vomiting, and a general feeling of malaise. Of those who contracted the bubonic plague, 4 out of 5 died within eight days.[36]

Pneumonic plague was the second most commonly seen form during the Black Death, with a mortality rate of ninety to ninety-five percent. Symptoms included fever, cough, and blood-tinged sputum. As the disease progressed, sputum became free flowing and bright red.

Septicemic plague was the least common of the three forms, with a mortality rate close to one hundred percent. Symptoms were high fevers and purple skin patches (purpura due to DIC).

David Herlihy identifies another potential sign of the plague: freckle-like spots and rashes.[37] Sources from Viterbo, Italy refer to "the signs which are vulgarly called lenticulae", a word which bears resemblance to the Italian word for freckles, lentiggini. These are not the swellings of buboes, but rather "darkish points or pustules which covered large areas of the body".

Malthusian crisis

Some historians have suggested another theory for the cause of the Black Death, one that points to social, agricultural and economic causes. Often known as the Malthusian limit, scholars use this term to express and explain tragedies throughout history. In his 1798 Essay on the Principle of Population, Thomas Malthus asserted that eventually humans would reproduce so greatly that they would go beyond the limits of food supplies; once they reached this point, some sort of "reckoning" was inevitable. While the Black Death may appear to be a "reckoning" of this sort, it was in fact an external, unpredictable factor and does not therefore fit into the Malthusian theory. In his book, The Black Death and the Transformation of the West, professor David Herlihy explores this idea of plague as an inevitable crisis wrought on humanity in order to control the population and human resources. In the book The Black Death; A Turning Point in History? (ed. William M. Bowsky) he writes "implies that the Black Death's pivotal role in late medieval society ... was now being challenged. Arguing on the basis of a neo-Malthusian economics, revisionist historians recast the Black Death as a necessary and long overdue corrective to an overpopulated Europe."

Herlihy also examined the arguments against the Malthusian crisis, stating "if the Black Death was a response to excessive human numbers it should have arrived several decades earlier"[38] due to the population growth of years before the outbreak of the Black Death. Herlihy also brings up other, biological factors that argue against the plague as a "reckoning" by arguing "the role of famines in affecting population movements is also problematic. The many famines preceding the Black Death, even the 'great hunger' of 1314 to 1317, did not result in any appreciable reduction in population levels".[38] Herlihy concludes the matter stating, "the medieval experience shows us not a Malthusian crisis but a stalemate, in the sense that the community was maintaining at stable levels very large numbers over a lengthy period" and states that the phenomenon should be referred to as more of a deadlock, rather than a crisis, to describe Europe before the epidemics.[38]:34



Figures for the death toll vary widely by area and from source to source as new research and discoveries come to light. It killed an estimated 75–200 million people in the 14th century.[39][40][41] According to medieval historian Philip Daileader in 2007:

The trend of recent research is pointing to a figure more like 45% to 50% of the European population dying during a four-year period. There is a fair amount of geographic variation. In Mediterranean Europe and Italy, the South of France and Spain, where plague ran for about four years consecutively, it was probably closer to 75% to 80% of the population. In Germany and England ... it was probably closer to 20%.[42]

The best estimate for the Middle East, including Iraq, Iran and Syria, during the Islamic Middle Ages is for a death rate of a third.[43] The Black Death killed about 40% of Egypt's population.[44] Half of Paris's population of 100,000 people had died. In Italy, Florence's population was reduced from 110,000 or 120,000 inhabitants in 1338 to 50,000 in 1351. At least 60% of Hamburg's and Bremen's population perished.[45] Before 1350, there were about 170,000 settlements in Germany, and this had been reduced by nearly 40,000 by 1450.[46] The governments of Europe had no apparent response to the crisis because no one knew its cause or how it spread. In 1348, the plague spread so rapidly that before any physicians or government authorities had time to reflect upon its origins, about a third of the European population had already perished. In crowded cities, it was not uncommon for as much as fifty percent of the population to die. Europeans living in isolated areas suffered less and monasteries and priests were especially hard hit since they cared for the Black Death's victims.[47] Because 14th century healers were at a loss to explain the cause, Europeans turned to astrological forces, earthquakes, and the poisoning of wells by Jews as possible reasons for the plague's emergence.[21] The mechanism of infection and transmission of diseases was unknown in the 14th century; many people believed only God's anger could produce such horrific displays. There were many attacks against Jewish communities.[48] In August of 1349, the Jewish communities of Mainz and Cologne were exterminated. In February of that same year, the citizens of Strasbourg murdered 2,000 Jews.[48] By 1351, 60 major and 150 smaller Jewish communities had been destroyed.[49]

Where government authorities were concerned, most monarchs instituted measures that prohibited exports of foodstuffs, condemned black market speculators, set price controls on grain and outlawed large-scale fishing. At best, they proved mostly unenforceable and at worst they contributed to a continent-wide downward spiral. The hardest hit lands, like England, were unable to buy grain abroad: from France because of the prohibition, and from most of the rest of the grain producers because of crop failures from shortage of labour. Any grain that could be shipped was eventually taken by pirates or looters to be sold on the black market. Meanwhile, many of the largest countries, most notably England and Scotland, had been at war, using up much of their treasury and exacerbating inflation. In 1337, on the eve of the first wave of the Black Death, England and France went to war in what would become known as the Hundred Years' War. Malnutrition, poverty, disease and hunger, coupled with war, growing inflation and other economic concerns made Europe in the mid-14th century ripe for tragedy. The Brotherhood of the Flagellants, a movement said to number up to 800,000, reached its peak of popularity.[50]


In England, in the absence of census figures, historians propose a range of pre-incident population figures from as high as 7 million to as low as 4 million in 1300,[51] and a post-incident population figure as low as 2 million.[52] By the end of 1350 the Black Death had subsided, but it never really died out in England over the next few hundred years: there were further outbreaks in 1361–62, 1369, 1379–83, 1389–93, and throughout the first half of the 15th century.[53] The plague often killed 10% of a community in less than a year—in the worst epidemics, such as at Norwich in 1579 and Newcastle upon Tyne in 1636, as many as 30 or 40%. The most general outbreaks in Tudor and Stuart England, all coinciding with years of plague in Germany and the Low Countries, seem to have begun in 1498, 1535, 1543, 1563, 1589, 1603, 1625, and 1636.[54]

The plague repeatedly returned to haunt Europe and the Mediterranean throughout the 14th to 17th centuries, and although bubonic plague still occurs in isolated cases today, the Great Plague of London in 1665–1666 is generally recognised as one of the last major outbreaks.[55]

In 1466, perhaps 40,000 people died of plague in Paris.[56] In 1570, as many as 200,000 may have died in Moscow and in the adjacent neighborhood.[57] The plague of 1575–77 claimed some perhaps 50,000 victims in Venice. In 1625, 35,417 Londoners had died of the plague.[58] In 1634, an outbreak of plague killed perhaps 15,000 Munich residents.[50] Late outbreaks in central Europe included the Italian Plague of 1629–1631, which is associated with troop movements during the Thirty Years' War, and the Great Plague of Vienna in 1679. About 200,000 people in Moscow died of the disease from 1654 to 1656.[59] Over 60% of Norway's population died from 1348 to 1350.[60] The last plague outbreak ravaged Oslo in 1654.[11] In 1656 the plague killed about half of Naples' 300,000 inhabitants.[61] Amsterdam was ravaged in 1663–1664, with a mortality given as 50,000.[62]

In the first half of the 17th century a plague claimed some 1,730,000 victims in Italy, or about 14% of the population.[63] More than 1,250,000 deaths resulted from the extreme incidence of plague in 17th century Spain.[64] In the Thirty Years' War, an estimated eight million Germans were killed by bubonic plague and typhus.[65] In 1710, a plague epidemic that followed the Great Northern War (1700–1721, Sweden v. Russia and allies) killed almost one third of the population in the region.[66] The plague killed two-thirds of the inhabitants of Helsinki,[67] and claimed a third of Stockholm's population.[68] Europe's last major epidemic occurred in 1720 in Marseilles.[60]

The Black Death ravaged much of the Islamic world.[69] Plague epidemics kept returning to the Islamic world up to the 19th century.[70] The cities of North Africa were especially hard hit by the disease. 30,000–50,000 died in Algiers in 1620–21, 1654–57, 1665, 1691, and 1740–42.[71]

The Third Pandemic started in China in the middle of the 19th century, spreading plague to all inhabited continents and killing 10 million people in India alone.[72] The plague bacterium could develop drug-resistance and again become a major health threat. The ability to resist many of the antibiotics used against plague has been found so far in only a single case of the disease in Madagascar.[73] From 1944 through 1993, 362 cases of human plague were reported in the United States; approximately 90% of these occurred in four western states.[74] Plague was confirmed in the United States from nine western states during 1995.[75]

In culture

The Black Death had a profound impact on art and literature throughout the generation that experienced it. Much of the most useful manifestations of the Black Death in literature, to historians, comes from the accounts of its chroniclers. Some of these chroniclers were famous writers, philosophers and rulers such as Boccaccio and Petrarch. Their writings, however, did not reach the majority of the European population. Petrarch's work was read mainly by wealthy nobles and merchants of Italian city-states. He wrote hundreds of letters and vernacular poetry, and passed on to later generations a revised interpretation of courtly love.[76] There was one troubadour, writing in the lyric style long out of fashion, who was active in 1348. Peire Lunel de Montech composed the sorrowful sirventes "Meravilhar no·s devo pas las gens" during the height of the plague in Toulouse.

They died by the hundreds, both day and night, and all were thrown in ... ditches and covered with earth. And as soon as those ditches were filled, more were dug. And I, Agnolo di Tura ... buried my five children with my own hands ... And so many died that all believed it was the end of the world.
The Plague in Siena: An Italian Chronicle[77]
How many valiant men, how many fair ladies, breakfast with their kinfolk and the same night supped with their ancestors in the next world! The condition of the people was pitiable to behold. They sickened by the thousands daily, and died unattended and without help. Many died in the open street, others dying in their houses, made it known by the stench of their rotting bodies. Consecrated churchyards did not suffice for the burial of the vast multitude of bodies, which were heaped by the hundreds in vast trenches, like goods in a ships hold and covered with a little earth.
Giovanni Boccaccio[78]

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