The Black Death: the greatest catastrophe ever

La Peste Negra, uno de los mayores desastres que asolaron la Europa medieval y, sin duda alguna, el que mayor número de muertos causó. Siempre nos acuden a la mente las mismas preguntas, ¿qué la produjo? y ¿cómo se propagó tan rápido por Europa? A través de algunos fragmentos escogidos de un artículo de la revista londinense History Today ofrezco al ocioso lector las respuestas a tales interrogantes. Por supuesto, el texto está extraído directamente del original en inglés –previa lectura y estudio concienzudo de este humilde escritor-.

Source: Ole J. Benedictow: The Black Death: the greatest catastrophe ever, In History Today Volume 55 Issue 3 March 2005.

Inspired by the Black Death, The Dance of Death or Danse Macabre, an allegory on the universality of death, is a common painting motif in the late medieval period

The disastrous mortal disease known as the Black Death spread across Europe in the years 1346-53 [...] Chronicles and letters from the time describe the terror wrought by the illness. In Florence, the great Renaissance poet Petrarch was sure that they would not be believed: ‘O happy posterity, who will not experience such abysmal woe and will look upon our testimony as a fable.’ A Florentine chronicler relates that:

All the citizens did little else except to carry dead bodies to be buried [...] At every church they dug deep pits down to the water-table; and thus those who were poor who died during the night were bundled up quickly and thrown into the pit. In the morning when a large number of bodies were found in the pit, they took some earth and shovelled it down on top of them; and later others were placed on top of them and then another layer of earth, just as one makes lasagne with layers of pasta and cheese.

The accounts are remarkably similar. The chronicler Agnolo di Tura ‘the Fat’ relates from his Tuscan home town that:

... in many places in Siena great pits were dug and piled deep with the multitude of dead [...] And there were also those who were so sparsely covered with earth that the dogs dragged them forth and devoured many bodies throughout the city.

The tragedy was extraordinary. In the course of just a few months, 60 per cent of Florence’s population died from the plague, and probably the same proportion in Siena [...]

The Black Death was an epidemic of bubonic plague, a disease caused by the bacterium Yersinia pestis that circulates among wild rodents where they live in great numbers and density. Such an area is called a ‘plague focus’ or a ‘plague reservoir’. Plague among humans  arises when rodents in human habitation, normally black rats, become infected. The black rat, also called the ‘house rat’ and the ‘ship rat’, likes to live close to people, the very quality that makes it dangerous (in contrast, the brown or grey rat prefers to keep its distance in sewers and cellars). Normally, it takes ten to fourteen days before plague has killed off most of a contaminated rat colony, making it difficult for great numbers of fleas gathered on the remaining, but soon- dying, rats to find new hosts. After three days of fasting, hungry rat fleas turn on humans. From the bite site, the contagion drains to a lymph node that consequently swells to form a painful bubo, most often in the groin, on the thigh, in an armpit or on the neck. Hence the name bubonic plague. The infection takes three–five days to incubate in people before they fall ill, and another three–five days before, in 80 per cent of the cases, the victims die. Thus, from the introduction of plague contagion among rats in a human community it takes, on average, twenty-three days before the first person dies.

When, for instance, a stranger called Andrew Hogson died from plague on his arrival in Penrith in 1597, and the next plague case followed twenty-two days later, this corresponded to the first phase of the development of an epidemic of bubonic plague. And Hobson was, of course, not the only fugitive from a plague-stricken town or area arriving in various communities in the region with infective rat fleas in their clothing or luggage. This pattern of spread is called ‘spread by leaps’ or ‘metastatic spread’. Thus, plague soon broke out in other urban and rural centres, from where the disease spread into the villages and townships of the surrounding districts by a similar process of leaps.

Illustration of the Black Death from the Toggenburg Bible (1411)

In order to become an epidemic the disease must be spread to other rat colonies in the locality and transmitted to inhabitants in the same way. It took some time for people to recognize that a terrible epidemic was breaking out among them and for chroniclers to note this. The timescale varies: in the countryside it took about forty days for realisation to dawn; in most towns with a few thousand inhabitants, six to seven weeks; in the  cities with over 10,000 inhabitants, about seven weeks, and in the few metropolises with over 100,000 inhabitants, as much as eight weeks.

Plague bacteria can break out of the buboes and be carried by the blood stream to the lungs and cause a variant of plague that is spread by contaminated droplets from the cough of patients (pneumonic plague). However, contrary to what is sometimes believed, this form is not contracted easily, spreads normally only episodically or incidentally and constitutes therefore normally only a small fraction of plague cases. It now appears clear that human fleas and lice did not contribute to the spread, at least not significantly. The bloodstream of humans is not invaded by plague bacteria from the buboes, or people die with so few bacteria in the blood that bloodsucking human parasites become insufficiently infected to become infective and spread the disease: the blood of plague-infected rats contains 500-1,000 times more bacteria per unit of measurement than the blood of plague-infected humans.

Importantly, plague was spread considerable distances by rat fleas on ships. Infected ship rats would die, but their fleas would often survive and find new rat hosts wherever they landed. Unlike human fleas, rat fleas are adapted to riding with their hosts; they readily also infest clothing of people entering affected houses and ride with them to other houses or localities. This gives plague epidemics a peculiar rhythm and pace of development and a characteristic pattern of dissemination. The fact that plague is transmitted by rat fleas means plague is a disease of the warmer seasons, disappearing during the winter, or at least lose most of their powers of spread. The peculiar seasonal pattern of plague has been observed everywhere and is a systematic feature also of the spread of the Black Death.

This conspicuous feature constitutes proof that the Black Death and plague in general is an insect-borne disease. Cambridge historian John Hatcher has noted that there is ‘a remarkable transformation in the seasonal pattern of mortality in England after 1348’: whilst before the Black Death the heaviest mortality was in the winter months, in the following century it was heaviest in the period from late July to late September. He points out that this strongly indicates that the ‘transformation was caused by the virulence of bubonic plague’.

It used to be thought that the Black Death originated in China, but new research shows that it began in the spring of 1346 in the steppe region, where a plague reservoir stretches from the north-western shores of the Caspian Sea into southern Russia. People occasionally contract plague there even today. Two contemporary chroniclers identify the estuary of the river Don where it flows into the Sea of Azov as the area of the original outbreak, but this could be mere hearsay, and it is possible that it started elsewhere, perhaps in the area of the estuary of the river Volga on the Caspian Sea. At the time, this area was under the rule of the Mongol khanate of the Golden Horde. Some decades earlier the Mongol khanate had converted to Islam and the presence of Christians, or trade with them, was no longer tolerated. As a result the Silk Road caravan routes between China and Europe were cut off. For the same reason the Black Death did not spread from the east through Russia towards western Europe, but stopped abruptly on the Mongol border with the Russian principalities. As a result, Russia which might have become the Black Death’s first European conquest, in fact was its last, and was invaded by the disease not from the east but from the west.

The epidemic in fact began with an attack that the Mongols launched on the Italian merchants’ last trading station in the region, Kaffa in the Crimea. In the autumn of 1346, plague broke out among the besiegers and from them penetrated into the town. When spring arrived, the Italians fled on their ships. And the Black Death slipped unnoticed on board and sailed with them.

The extent of the contagious power of the Black Death has been almost mystifying. The central explanation lies within characteristic features of medieval society in a dynamic phase of modernisation heralding the transformation from a medieval to early modern European society. Early industrial market-economic and capitalistic developments had advanced more than is often assumed, especially in northern Italy and Flanders. New, larger types of ship carried great quantities of goods over extensive trade networks that linked Venice and Genoa with Constantinople and the Crimea, Alexandria and Tunis, London and Bruges. In London and Bruges the Italian trading system was linked to the busy shipping lines of the German Hanseatic League in the Nordic countries and the Baltic area, with large broad-bellied ships called cogs.

The strong increase in population in Europe in the High Middle Ages (1050-1300) meant that the prevailing agricultural technology was inadequate for further expansion. To accommodate the growth, forests were cleared and mountain villages settled wherever it was possible for people to eke out a living. People had to opt for a more one-sided husbandry, particularly in animals, to create a surplus that could be traded for staples such as salt and iron, grain or flour. These settlements operated within a busy trading network running from coasts to mountain villages. And with tradesmen and goods, contagious diseases reached even the most remote and isolated hamlets.

Much new can be said on the Black Death’s patterns of territorial spread. Of particular importance was the sudden appearance of the plague over vast distances, due to its rapid transportation by ship. Ships travelled at an average speed of around 40km a day which today seems quite slow. However, this speed meant that the Black Death easily moved 600km in a fortnight by ship: spreading, in contemporary terms, with astonishing speed and unpredictability. By land, the average spread was much slower: up to 2km per day along the busiest highways or roads and about 0.6km per day along secondary lines of communication.

As already noted, the pace of spread slowed strongly during the winter and stopped completely in mountain areas such as the Alps and the northerly parts of Europe. Yet, the Black Death often rapidly established two or more fronts and conquered countries by advancing from various quarters.

Italian ships from Kaffa arrived in Constantinople in May 1347 with the Black Death on board. The epidemic broke loose in early July. In North Africa and the Middle East, it started around September 1st, having arrived in Alexandria with ship transport from Constantinople. Its spread from Constantinople to European Mediterranean commercial hubs also started in the autumn of 1347. It reached Marseilles by about the second week of September, probably with a ship from the city. Then the Italian merchants appear to have left Constantinople several months later and arrived in their home towns of Genoa and Venice with plague on board, some time in November. On their way home, ships from Genoa also contaminated Florence’s seaport city of Pisa. These great commercial cities also functioned as bridgeheads from where the disease conquered Europe.

In Mediterranean Europe, Marseilles functioned as the first great centre of spread. The relatively rapid advance both northwards up the Rhône valley to Lyons and south-westwards along the coasts towards Spain – in chilly months with relatively little shipping activity – is striking. As early as March 1348, both Lyon’s and Spain’s Mediterranean coasts were under attack.

En route to Spain, the Black Death also struck out from the city of Narbonne north-westwards along the main road to the commercial centre of Bordeaux on the Atlantic coast, which by the end of March had become a critical new centre of spread. Around April 20th, a ship from Bordeaux must have arrived in La Coruña in northwestern Spain; a couple of weeks later another ship from there let loose the plague in Navarre in northeastern Spain. Thus, two northern plague fronts were opened less than two months after the disease had invaded southern Spain.

Detailed study of the mortality data available points to two conspicuous features in relation to the mortality caused by the Black Death: namely the extreme level of mortality caused by the Black Death, and the remarkable similarity or consistency of the level of mortality, from Spain in southern Europe to England in north-western Europe. The data is sufficiently widespread and numerous to make it likely that the Black Death swept away around 60 per cent of Europe’s population. It is  generally assumed that the size of Europe’s population at the time was around 80 million. This implies that around 50 million people died in the Black Death.

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