Monday, March 30, 2020

Did bubonic plague really cause the Black Death?

Everyone thinks the Black Death was caused by bubonic plague. But they could be wrong – and we need to find the real culprit before it strikes again

By Debora Mackenzie 24 November 2001

THE DISEASE that spread like wildfire through Europe between 1347 and 1351 is still the most violent epidemic in recorded history. It killed at least a third of the population, more than 25 million people. Victims first suffered pain, fever and boils, then swollen lymph nodes and blotches on the skin. After that they vomited blood and died within three days. The survivors called it the Great Pestilence. Victorian scientists dubbed it the Black Death.

As far as most people are concerned, the Black Death was bubonic plague, Yersinia pestis, a flea-borne bacterial disease of rodents that jumped to humans. But two epidemiologists from Liverpool University say we’ve got it all wrong. In Biology of Plagues, a book released earlier this year, they effectively demolish the bubonic plague theory. “If you look at how the Black Death spread,” says Susan Scott, one of the authors, “one of the least likely diseases to have caused it is bubonic plague.” If Scott and co-author Christopher Duncan are right, the world would do well to listen.

Whatever pathogen caused the Black Death appears to have ravaged Europe several times during the past two millennia, and it could resurface again. If we knew what it really was, we could prepare for it. “It’s always important to re-evaluate these questions so we are not taken by surprise,” says Steve Morse, an expert on emerging viral diseases at Columbia University in New York. Yet few experts in infectious diseases have even read the book, let alone taken its ideas seriously. New Scientist has, and it looks to us as though Scott and Duncan are on to something.

The idea that the Black Death was bubonic plague dates back to the late 19th century, when Alexandre Yersin, a French bacteriologist, unravelled the complex biology of bubonic plague. He noted that the disease shared a key feature with the Black Death: the bubo, a dark, painful, swollen lymph gland usually in the armpit or groin. Even though buboes also occur in other diseases, he decided the two were the same, even naming the bacterium pestis after the Great Pestilence.

But the theory is riddled with glaring flaws, say Scott and Duncan. First of all, bubonic plague is intimately associated with rodents and the fleas they carry. But the Black Death’s pattern of spread doesn’t fit a rat and flea-borne disease. It raced across the Alps and through northern Europe at temperatures too cold for fleas to hatch, and swept from Marseilles to Paris at four kilometres a day – -far faster than a rat could travel. Moreover, the rats necessary to spread the disease simply were not there. The only rat in Europe in the Middle Ages was the black rat, Rattus rattus, which stays close to human habitation. Yet the Black Death jumped across great tracts of open country-up to 300 kilometres between towns in France-in only a few days with no intermediate outbreaks. “Iceland had no rats at all,” notes Duncan, “but the Black Death was reported there too.”

In contrast, bubonic plague spreads, as rats do, slowly and sporadically. In 1907, the British Plague Commission in India reported an outbreak that took six months to move 300 feet. After bubonic plague arrived in South Africa in 1899, it moved inland at just 20 kilometres a year, even with steam trains to help.

The disease that caused the Black Death stayed in Europe until 1666. During its 300-year reign, Scott and Duncan have found records of outbreaks that occurred somewhere in France virtually every year. Every few years, these outbreaks spawned epidemics that ravaged the rest of Europe. For Yersinia to do this, it would have to become established in a population of rodents that are resistant to the disease. It couldn’t have been rats, because the plague bacterium kills them-along with all other European rodents. As a result, Europe, along with Australia and Antarctica, remain the only regions of the world where bubonic plague has never settled. So, once again, the Black Death behaved in a way plague simply cannot.

Nor is bubonic plague contagious enough to have been the Black Death. The Black Death killed at least a third of the population wherever it hit, sometimes more. But when bubonic plague hit India in the 19th century, fewer than 2 per cent of the people in affected towns died. And when plague invaded southern Africa, South America and the south-western US, it didn’t trigger a massive epidemic.

The most obvious problem with the plague theory is that, unlike bubonic plague, the Black Death obviously spread directly from person to person. People in the thick of the epidemic recognised this, and Scott and Duncan proved they were right by tracing the anatomy of outbreaks, person by person, using English burial records from the 16th century. These records, which detail all deaths from the pestilence by order of Elizabeth I, clearly show the disease spreading from one person to their neighbours and relatives, separated by an incubation period of 20 to 30 days.

The details tally perfectly with a disease that kills about 37 days after infection. For the first 10 to 12 days, you weren’t infectious. Then for 20 to 22 days, you were. You only knew you were infected when you fell ill, for the final five days or less-but by then you had been infecting people unknowingly for weeks. Europeans at the time clearly knew the disease had a long, infectious incubation period, because they rapidly imposed measures to isolate potential carriers. For example, they stopped anyone arriving on a ship from disembarking for 40 days, or quarantina in Italian – -the origin of the word quarantine.
Telltale timing

Epidemiologists know that diseases with a long incubation time create outbreaks that last months. From 14th-century ecclesiastical records, Scott and Duncan estimate that outbreaks of the Black Death in a given town or diocese typically lasted 8 or 9 months. That, plus the delay between waves of cases, is the fingerprint of the disease across Europe over seasons and centuries, they say. The pair found exactly the same pattern in 17th-century outbreaks in Florence, Milan and a dozen towns across England, including London, Colchester, Newcastle, Manchester and Eyam in Derbyshire. In 1665, the inhabitants of Eyam selflessly confined themselves to the village. A third of them died, but they kept the disease from reaching other towns. This would not have worked if the carriers were rats.

Despite the force of their argument, Scott and Duncan have yet to convince their colleagues. None of the experts that New Scientist spoke to had read their book, and a summary of its ideas provoked reactions that range from polite interest to outright dismissal. Some of Scott’s colleagues, for example, have scoffed that “everyone knows the Black Death was bubonic plague”.

“I doubt you can say plague was not involved in the Black Death, though there may have been other diseases too,” says Elisabeth Carniel, a bubonic plague expert at the Pasteur Institute in Paris. “But I haven’t had time to read the book.” Carniel suggests that fleas could have spread the Black Death directly between people. Human fleas can keep it in their guts for a few weeks, leading to a delay in spread. But this would be unlikely to have happened the same way every time.

Moreover, people with enough Yersinia in their blood for a flea to pick it up are already very sick. They would only be able to pass their infection on in this way for a very short time-and whoever the flea bit would also sicken within a week, the incubation time of Yersinia. This does not fit the pattern documented by Scott and Duncan. Neither would an extra-virulent Yersinia, which would still depend on rats.

There have been several other ingenious attempts to save the Yersinia theory as inconsistencies have emerged. Many fall back on pneumonic plague, a variant form of Yersinia infection. This can occur in the later stages of bubonic plague, when the bacteria sometimes proliferate in the lungs and can be coughed out, and inhaled by people nearby. Untreated pneumonic plague is invariably fatal and can spread directly from person to person.

But not far, and not for long-plague only becomes pneumonic when the patient is practically at death’s door. “It is simply impossible that people sick enough to have developed the pneumonic form of the disease could have travelled far,” says Scott. Yet the Black Death typically jumped between towns in the time a healthy human took to travel. Also, pneumonic plague kills quickly-within six days, usually less. With such a short infectious period, local outbreaks of pneumonic plague end much sooner than 8 or 9 months, notes Scott. Rats and fleas can restart them, but then the disease is back to spreading slowly and sporadically like flea-borne diseases. Moreover, pneumonic plague lacks the one thing that links Yersinia to the Black Death: buboes.

If the Black Death wasn’t bubonic plague, then what was it? Possibly-and ominously-it may have been a virus. The evidence comes from a mutant protein on the surface of certain white blood cells. The protein, CCR5, normally acts as a receptor for the immune signalling molecules called chemokines, which help control inflammation. The AIDS virus and the poxvirus that causes myxomatosis in rabbits also use CCR5 as a docking port to enter and kill immune cells.

In 1998, a team led by Stephen O’Brien of the US National Cancer Institute analysed a mutant form of CCR5 that gives some protection against HIV. From its pattern of occurrence in the population, they think it arose in north-eastern Europe some 2000 years ago-and around 700 years ago, something happened to boost its incidence from 1 in 40,000 Europeans to 1 in 5. “It had to have been a breathtaking selective pressure to jack it up that high,” says O’Brien. The only plausible explanation, he thinks, is that the mutation helped its carriers survive the Black Death. In fact, say Scott and Duncan, Europeans did seem to grow more resistant to the disease between the 14th and 17th centuries.

Yersinia, too, enters and kills immune cells when it causes disease. But when O’Brien’s team pitted Yersinia against blood cells from people with and without the mutation, they found no dramatic difference. “The results were equivocal,” says O’Brien. “We don’t know if the mutation protected or not.” Further experiments are under way. Similar mutations occur elsewhere in the world, but at nowhere near the high frequency of the European mutant. This suggests that pathogens such as smallpox exerted some selective force, but nothing like whatever happened in Europe, says O’Brien.

The association between CCR5 and viruses suggests that the Black Death was a virus too. Its sudden emergence, and equally sudden disappearance after the Great Plague of London in 1666, also argue for a viral cause. Like the deadly flu of 1918, viruses can sometimes mutate into killers, and then disappear.

But what sort of virus was the Black Death? Scott and Duncan suggest a haemorrhagic filovirus such as Ebola, since the one consistent symptom was bleeding. In fact they think “haemorrhagic plague” would be a good new name for the disease.

They are not the first to blame Ebola for an ancient plague. Scientists and classicists in San Diego reported in 1996 that the symptoms of the plague of Athens around 430 BC, described by Thucydides, are remarkably similar to Ebola, including a distinctive retching or hiccupping. Apart from that, many of the symptoms of that plague- – and one in Constantinople in AD 540 – -were similar to the Black Death.

Of course, the filoviruses we know about are relatively hard to catch, with an incubation period of a week or less, not three weeks or more. But there are other haemorrhagic viruses: Lassa fever in Africa is fairly contagious, and incubates for up to three weeks. Eurasian hantaviruses can incubate for up to 42 days, but are not usually directly contagious between people. Both can be as deadly as the Black Death.
Out of Africa

Perhaps we can narrow the search to Africa. Europeans first recorded the Black Death in Sicily in 1347. The Sicilians blamed it on Genoese galleys that arrived from Crimea just as the illness exploded. But the long incubation period means the infection must have arrived earlier. Scott suspects it initially came from Africa, just a short hop away from Sicily. That continent is historically the home of more human pathogens than any other, and the people who lived through the epidemics that wracked Athens and Constantinople said their disease came from there. The epidemic in Constantinople, for instance, seems to have come via trade routes from the Central African interior. “And I’m sure that disease was the same as the Black Death,” says O’Brien.

One way to solve the puzzle could be to look for the pathogen’s DNA in the plague pits of Europe. Didier Raoult and colleagues at the University of the Mediterranean in Marseilles examined three skeletons in a 14th-century mass grave in Montpellier last year (New Scientist, 11 November 2000, p 31). They searched the skeletons for fragments of DNA unique to several known pathogens-Yersinia, anthrax or typhus. They found one match: Yersinia. In their report they wrote: “We believe that we can end the controversy. Medieval Black Death was [bubonic] plague.”

Not so fast, says Scott. Southern France probably had bubonic plague at that time, even if it wasn’t the Black Death. Moreover, attempts by Alan Cooper, director of the Ancient Biomolecules Centre at Oxford University, and Raoult’s team to replicate the results have so far failed, says Cooper. Similar attempts to find Yersinia DNA at mass graves in London, Copenhagen and another burial in southern France have also failed.

It’s too early to conclude that the failure to find Yersinia DNA means the bacterium wasn’t there, though. The art of retrieving ancient DNA is still in its infancy, Cooper warns. Pathogen DNA – -especially that of fragile viruses – -is extremely difficult to reliably identify in remains that are centuries old. “The pathogen decays along with its victim,” he says. Scientists have had difficulty, for example, in retrieving the 1918 flu virus, even from bodies less than a century old and preserved by permafrost. And even if the technique for retrieving ancient DNA improves, you need to know what you’re searching for. There is no way now to search for an unknown haemorrhagic virus.

But the possibility that the Black Death could strike again should give scientists the incentive to keep trying. The similarity of the catastrophes in Athens, Constantinople and medieval Europe suggests that whatever the pathogen is, it comes out of hiding every few centuries. And the last outbreak was its fastest and most murderous. What would it do in the modern world? Maybe we should find it, before it finds us.

Further reading:Biology of plagues: Evidence from historical populationsby Susan Scott and Christopher Duncan, Cambridge University Press (2001)

Read more: https://www.newscientist.com/article/mg17223184-000-did-bubonic-plague-really-cause-the-black-death/#ixzz6IBKqNk2x

The Black Death: The Greatest Catastrophe Ever

Miniature out of the Toggenburg Bible (Switzerland) of 1411.

The disease is widely believed to be the plague, although the location

of bumps and blisters is more consistent with smallpox.

FEATURE

The Black Death: The Greatest Catastrophe Ever

Ole J. Benedictow describes how he calculated that the Black Death killed 50 million people in the 14th century, or 60 per cent of Europe’s entire population.

Ole Benedictow | Published in History Today Volume 55 Issue 3 March 2005

The disastrous mortal disease known as the Black Death spread across Europe in the years 1346-53. The frightening name, however, only came several centuries after its visitation (and was probably a mistranslation of the Latin word ‘atra’ meaning both ‘terrible’ and ‘black)’. 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. In addition to the bald statistics, we come across profound personal tragedies: Petrarch lost to the Black Death his beloved Laura to whom he wrote his famous love poems; Di Tura tells us that ‘I [...] buried my five children with my own hands’.

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.

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. In the plague history of Norway from the Black Death 1348-49 to the last outbreaks in 1654, comprising over thirty waves of plague, there was never a winter epidemic of plague. Plague is very different from airborne contagious diseases, which are spread directly between people by droplets: these thrive in cold weather.

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’.

***

Another very characteristic feature of the Black Death and plague epidemics in general, both in the past and in the great outbreaks in the early twentieth century, reflects their basis in rats and rat fleas: much higher proportions of inhabitants contract plague and die from it in the countryside than in urban centres. In the case of English plague history, this feature has been underlined by Oxford historian Paul Slack. When around 90 per cent of the population lived in the countryside, only a disease with this property combined with extreme lethal powers could cause the exceptional mortality of the Black Death and of many later plague epidemics. All diseases spread by cross-infection between humans, on the contrary, gain increasing powers of spread with increasing density of population and cause highest mortality rates in urban centres.

Lastly it could be mentioned that scholars have succeeded in extracting genetic evidence of the causal agent of bubonic plague, the DNA-code of Yersinia pestis, from several plague burials in French cemeteries from the period 1348-1590.

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 (today Feodosiya) 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. This system for long-distance trade was supplemented by a web of lively short and medium-distance trade that bound together populations all over the Old World.

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.

In this early phase of modernisation, Europe was also on the way to ‘the golden age of bacteria’, when there was a great increase in epidemic diseases caused by increases in population density and in trade and transport while knowledge of the nature of epidemics, and therefore the ability to organise efficient countermeasures to them, was still minimal. Most people believed plague and mass illness to be a punishment from God for their sins. They responded with religious penitential acts aimed at tempering the Lord’s wrath, or with passivity and fatalism: it was a sin to try to avoid God’s will.

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.

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.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. The spread out of Pisa is characterized by a number of metastatic leaps. 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.

Another plague ship sailed from Bordeaux, northwards to Rouen in Normandy where it arrived at the end of April. There, in June, a further plague front moved westwards towards Brittany, south-eastwards towards Paris and northwards in the direction of the Low Countries.

Yet another ship bearing plague left Bordeaux a few weeks later and arrived around May 8th, in the southern English town of Melcombe Regis, part of present-day Weymouth in Dorset: the epidemic broke out shortly before June 24th. The significance of ships in the rapid transmission of contagion is underscored by the fact that at the time the Black Death landed in Weymouth it was still in an early phase in Italy. From Weymouth, the Black Death spread not only inland, but also in new metastatic leaps by ships, which in some cases must have travelled earlier than the recognized outbreaks of the epidemic: Bristol was contaminated in June, as were the coastal towns of the Pale in Ireland; London was contaminated in early August since the epidemic outbreak drew comment at the end of September. Commercial seaport towns like Colchester and Harwich must have been contaminated at about the same time. From these the Black Death spread inland. It is now also clear that the whole of England was conquered in the course of 1349 because, in the late autumn of 1348, ship transport opened a northern front in England for the Black Death, apparently in Grimsby.

***

The early arrival of the Black Death in England and the rapid spread to its southeastern regions shaped much of the pattern of spread in Northern Europe. The plague must have arrived in Oslo in the autumn of 1348, and must have come with a ship from south-eastern England, which had lively commercial contacts with Norway. The outbreak of the Black Death in Norway took place before the disease had managed to penetrate southern Germany, again illustrating the great importance of transportation by ship and the relative slowness of spread by land. The outbreak in Oslo was soon stopped by the advent of winter weather, but it broke out again in the early spring. Soon it spread out of Oslo along the main roads inland and on both sides of the Oslofjord. Another independent introduction of contagion occurred in early July 1349 in the town of Bergen; it arrived in a ship from England, probably from King’s Lynn. The opening of the second plague front was the reason that all Norway could be conquered in the course of 1349. It disappeared completely with the advent of winter, the last victims died at the turn of the year.

The early dissemination of the Black Death to Oslo, which prepared the ground for a full outbreak in early spring, had great significance for the pace and pattern of the Black Death’s further conquest of Northern Europe. Again ship transport played a crucial role, this time primarily by Hanseatic ships fleeing homewards from their trading station in Oslo with goods acquired during the winter. On their way the seaport of Halmstad close to the Sound was apparently contaminated in early July. This was the starting point for the plague’s conquest of Denmark and Sweden, which was followed by several other independent introductions of plague contagion later; by the end of 1350 most of these territories had been ravaged.

However, the voyage homewards to the Hanseatic cities on the Baltic Sea had started significantly earlier. The outbreak of the Black Death in the Prussian town of Elbing (today the Polish town of Elblag) on August 24th, 1349, was a new milestone in the history of the Black Death. A ship that left Oslo at the beginning of June would probably sail through the Sound around June 20th and reach Elbing in the second half of July, in time to unleash an epidemic outbreak around August 24th. Other ships that returned at the end of the shipping season in the autumn from the trading stations in Oslo or Bergen, brought the Black Death to a number of other Hanseatic cities both on the Baltic Sea and the North Sea. The advent of winter stopped the outbreaks initially as had happened elsewhere, but contagion was spread with goods to commercial towns and cities deep into northern Germany. In the spring of 1350, a northern German plague front was formed that spread southwards and met the plague front which in the summer of 1349 had formed in southern Germany with importation of contagion from Austria and Switzerland.

***

Napoleon did not succeed in conquering Russia. Hitler did not succeed. But the Black Death did. It entered the territory of the city state of Novgorod in the late autumn of 1351 and reached the town of Pskov just before the winter set in and temporarily suppressed the epidemic; thus the full outbreak did not start until the early spring of 1352. In Novgorod itself, the Black Death broke out in mid-August. In 1353, Moscow was ravaged, and the disease also reached the border with the Golden Horde, this time from the west, where it petered out. Poland was invaded by epidemic forces coming both from Elbing and from the northern German plague front and, apparently, from the south by contagion coming across the border from Slovakia via Hungary.

Iceland and Finland are the only regions that, we know with certainty, avoided the Black Death because they had tiny populations with minimal contact abroad. It seems unlikely that any other region was so lucky.

How many people were affected? Knowledge of general mortality is crucial to all discussions of the social and historical impact of the plague. Studies of mortality among ordinary populations are far more useful, therefore, than studies of special social groups, whether monastic communities, parish priests or social elites. Because around 90 per cent of Europe’s population lived in the countryside, rural studies of mortality are much more important than urban ones.

Researchers generally used to agree that the Black Death swept away 20-30 per cent of Europe’s population. However, up to 1960 there were only a few studies of mortality among ordinary people, so the basis for this assessment was weak. From 1960, a great number of mortality studies from various parts of Europe were published. These have been collated and it is now clear that the earlier estimates of mortality need to be doubled. No suitable sources for the study of mortality have been found in the Muslim countries that were ravaged.

The mortality data available reflects the special nature of medieval registrations of populations. In a couple of cases, the sources are real censuses recording all members of the population, including women and children. However, most of the sources are tax registers and manorial registers recording households in the form of the names of the householders. Some registers aimed at recording all households, also the poor and destitute classes who did not pay taxes or rents, but the majority recorded only householders who paid tax to the town or land rent to the lord of the manor. This means that they overwhelmingly registered the better-off adult men of the population, who for reasons of age, gender and economic status had lower mortality rates in plague epidemics than the general population. According to the extant complete registers of all households, the rent or tax-paying classes constituted about half the population both in the towns and in the countryside, the other half were too poor. Registers that yield information on both halves of the populations indicate that mortality among the poor was 5-6 per cent higher. This means that in the majority of cases when registers only record the better-off half of the adult male population, mortality among the adult male population as a whole can be deduced by adding 2.5-3 per cent.

Another fact to consider is that in households where the householder survived, other members often died. For various reasons women and children suffer higher incidence of mortality from plague than adult men. A couple of censuses produced by city states in Tuscany in order to establish the need for grain or salt are still extant. They show that the households were, on average, reduced in the countryside from 4.5 to 4 persons and in urban centres from 4 to 3.5 persons. All medieval sources that permit the study of the size and composition of households among the ordinary population produce similar data, from Italy in southern Europe to England in the west and Norway in northern Europe. This means that the mortality among the registered households as a whole was 11-12.5 per cent higher than among the registered householders.

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 that around 50 million people died in the Black Death. This is a truly mind-boggling statistic. It overshadows the horrors of the Second World War, and is twice the number murdered by Stalin’s regime in the Soviet Union. As a proportion of the population that lost their lives, the Black Death caused unrivalled mortality.

This dramatic fall in Europe’s population became a lasting and characteristic feature of late medieval society, as subsequent plague epidemics swept away all tendencies of population growth. Inevitably it had an enormous impact on European society and greatly affected the dynamics of change and development from the medieval to Early Modern period. A historical turning point, as well as a vast human tragedy, the Black Death of 1346-53 is unparalleled in human history.

Ole J. Benedictow is Emeritus Professor of History at the Universtiy of Oslo, Norway.

Black Death facts: your guide to “the worst catastrophe in recorded history”

The Black Death of October 1347 to c1352 was one of the worst catastrophes in recorded history – a deadly bubonic plague that ravaged communities across Europe, changing forever their social and economic fabric. But how much do you know about the Black Plague? How many died? Did the epidemic really eradicate a third of Europe's population? And did it afflict every town and village?

March 23, 2020 at 10:05 am

Following the outbreak of Covid-19, a disease known as coronavirus, stories about the Black Death are seemingly in the news more than ever. It is estimated that 50 million people died as a result of the deadly plague. But what caused the disease? Where did it start? And what were its symptoms? Here’s your guide to the illness that ravaged Europe between 1347 and 1348…

Questions answered by Professor Samuel Cohn and Professor Tom Beaumont James

What was the Black Death?

In the Middle Ages, the Black Death, or ‘pestilencia’, as contemporaries called various epidemic diseases, was the worst catastrophe in recorded history. Some dubbed it ‘magna mortalitas’ (great mortality), emphasising the death rate.

It destroyed a higher proportion of the population than any other single known event

It destroyed a higher proportion of the population than any other single known event. One observer noted “the living were scarcely sufficient to bury the dead”. No one could be sure what caused the deadly plague.

When was the Black Death?

The plague arrived in western Europe in 1347 and in England in 1348. It faded away in the early 1350s.

What were the symptoms of the Black Death?

Symptoms of the Black Death included swellings – most commonly in the groin, armpits and neck; dark patches, and the coughing up of blood.

Medieval observers – and their modern counterparts in 19th-century China and 20th-century Vietnam, observing more recent outbreaks – noted that different strains of the disease took from five days to as little as half a day to cause death.

How many people died because of the Black Death?

In Europe, it is thought that around 50 million people died as a result of the Black Death over the course of three or four years. The population was reduced from some 80 million to 30 million. It killed at least 60 per cent of the population in rural and urban areas. In fact, in some places such as a village on an estate in Cambridgeshire manorial rolls attest that 70 per cent of its tenants died in a matter of months in 1349, and the city of Florence tax records drawn up shortly before and after the Black Death suggest that its toll may have been about the same in 1348.

It is thought that around 50 million people died as a result of the Black Death

Some communities such as Quob in Hampshire were wiped out; many rural communities went into decline (and were in time deserted). We know that some populations survived, but medieval people had no such knowledge – all they believed was that everyone would certainly die.

The plague skipped over or barely touched some European villages, and may not have infected at all vast regions (such as ones in northern German-speaking lands). Given the state of record-keeping and preservation, we will probably never be able to estimate the Black Death’s European toll with any precision.

What remedies were used to treat the Black Death?

Medieval people believed that the Black Death came from God, and so responded with prayers and processions. Some contemporaries realised that the only remedy for plague was to run away from it – Boccaccio’s Decameron is a series of tales told among a group of young people taking refuge from the Black Death outside Florence.

There was no known remedy, but people wanted medicines

There was no known remedy, but people wanted medicines: Chaucer commented that the Doctor of Physic made much ‘gold’ out of the pestilence. The plague bacteria were identified in Asia in the 1890s, and the connection with animals and fleas established.

Modern antibiotics can combat plague, but these are under threat from mutating diseases and immunity to antibiotics’ effects.

Where did the Black Death originate, and what areas did it affect?

Breaking out in ‘the east’, as medieval people put it, the Black Death came north and west after striking the eastern Mediterranean and Italy, Spain and France.

It then came to Britain, where it struck Dorset and Hampshire along the south coast of England simultaneously. The plague then spread north and east, then on to Scandinavia and Russia.

How did the Black Death spread? Was it because of black rats transmitting the plague to humans via fleas?

Not only textbooks but serious monographs on the Black Death and its successive waves of plague into the early 19th century in Europe go on about rats (usually “black ones”) and fleas without qualification. But what is the evidence?

No contemporary observers described any epizootic [animal epidemic] of rats or of any other rodents immediately before or during the Black Death, or during any later plagues in Europe – that is, until the ‘third pandemic’ at the end of the 19th century. Yet in subtropical regions of Africa and China, descriptions of ‘rat falls’ accompanying a human disease with buboes in the principal lymph nodes reach back at least to the 18th century.

As for fleas, unlike during the ‘third pandemic’, when plague cases and deaths followed closely the seasonal fertility cycles of various species of rat fleas, no such correlations are found with the Black Death or later European plagues before the end of the 19th century.

The lethality of the Black Death arose from the onslaught of three types: bubonic, pneumonic and, occasionally, septicaemic plague.

Who was most affected by the plague? Did the Black Death mainly affect poor people?

Old and young. Men and women. All of society – royalty, peasants, archbishops, monks, nuns and parish clergy – was affected. No subset of people was immune to the Black Death.

Contemporary chroniclers list important knights, ladies, and merchants who died during the Black Death. Many wealthy and well-fed convents, friaries, and monasteries across Europe lost more than half of their members, with some becoming extinct.

Both artisan and artistic skills were lost or severely affected, from cathedral building in Italy to pottery production in England. Artists such as the Lorinzetti brothers of Siena were victims, and the English royal masons, the Ramseys, died. There were shortages of people to till the land and tend cattle and sheep.

By the third or fourth wave of plague in the last decades of the 14th century, burial records and tax registers suggest that the disease had evolved into one that largely affected the poor.

Which areas were worst hit by the Black Death?

In 1348–49, some of the worst-hit regions were in mountainous and in relatively isolated zones, such as in Snowdonia in Wales or the mountain village of Mangona in the Alpi fiorentine, north of Florence, whose communications with cities were less frequent than places further down the slopes and closer to cities.

The experiences of these isolated villages may have been similar to small mining villages in Pennsylvania or in South Africa, or Inuit settlements in Newfoundland under attack by another highly contagious pandemic, the Great Influenza of 1918–19, in which they experienced mortalities from 10 to 40 per cent – many times higher than in New York City or London.

For reasons that are difficult to explain, cities such as Milan and Douai in Flanders, both major hubs of commerce and industry, appear to have escaped the Black Death in 1348 almost totally unscathed.

In the case of Milan, only one household fell victim to the disease, at least according to chronicles, and the plague was successfully contained. Meanwhile, Douai chronicles, monastic necrologies, and archival records (recording, for example, the deaths of magistrates, and last wills and testaments) show no certain signs of the plague entering that city until the plague of 1400.

Did the Black Death result in the massacre of Jews or the blaming of other minorities?

In German-speaking lands, France along the Rhine, and parts of Spain, municipal governments, castellans, bishops, and the Holy Roman Emperor accused Jews of spreading the Black Death by poisoning foodstuffs and water sources, and massacred entire communities of men, women, and babies for these supposed crimes.

The accusations and massacres, however, were not universal between 1348 and 1351. Massacres did not arise in the British Isles (where, at least in England, Jews had been expelled in 1290 by Edward I), and no clear evidence pinpoints any such violence in Italy (except for the Catalans in Sicily). Nor are any massacres recorded in the Middle East.

Where did the first ‘quarantine’ take place?

The phrase ‘quarantine’ (the exclusion and isolation of those coming from infected regions, or of others suspected of carrying plague, to avoid them mixing with uninfected populations for a certain number of days) was coined in Venice in the early 15th century, based on a 40-day period of isolation (with Biblical resonances). But the city of Ragusa [present-day Dubrovnik] had beaten the Venetians to the punch in 1377 with a plague ‘quarantine’ of 30 days.

By the early modern period, ‘quarantine’ often had been curtailed further. The period deemed necessary to isolate suspected carriers in Milan during its plague of 1557–75, for instance, had dropped to eight daysfor certain categories of suspicion.

Were efforts to reduce the spread of the Black Death in vain?

Cities that managed to keep plague beyond their borders were those that devised and implemented quarantine: border controls at city gates, harbours, and mountain passes; individual health passports (which identified a person and certified where he or she came from), and other related measures such as spy networks to signal when a plague had erupted in a foreign city or region.

Cities that managed to keep plague beyond their borders were those that devised and implemented quarantine

Ragusa was a pioneer in this regard, with its earliest ‘quarantine’ and its increasingly sophisticated measures to isolate the infected and control its borders during the late 14th and 15th centuries. Its last plague was in 1533, while in England it was 1665–56, in the Baltic region 1709–13, and Northern Africa and the Middle East the 19th century. Many Italian regions followed Ragusa’s lead, and after them, other regions of western and central Europe.

Did the church recognise anyone who sacrificed their lives to help those afflicted during the Black Death?

From October 1347 in Sicily to the early 1350s further north, contemporary chroniclers decried the abandonment of sick family members, and criticised clergymen and doctors who were ‘cowardly’ in reneging on their responsibilities to escape the plague’s vicious contagion. However, occasionally contemporary writers also praised those who stayed on to nurse the afflicted, and who often lost their lives in so doing.

Curiously, the church did not recognise any of these martyrs during the Black Death with elevations to beatitude or sanctity.

The first to be so recognised did not appear until the 15th century, and those who intervened to help those afflicted by the plague (that is, during their own lifetimes and not as post-mortem miraculous acts) remained rare even during 16th and 17th centuries.

How quickly did the Black Death spread?

It is thought that the Black Death spread at a rate of a mile or more a day, but other accounts have measured it in places to have averaged as far as eight miles a day. It is thought that the Black Death travelled 30 to 100 times faster over land than the bubonic plagues of the 20th century; indeed, Scientists in South Africa, New Orleans, and other places affected by bubonic plague in the early 20th century devised experiments to clock their plague’s spread, and found it moved no faster than eight miles a year. It spread so slowly because modern bubonic plague was a rodent disease – and often one dependent on the house rat.

These extreme differences in the spread of the Black Death and the bubonic plagues of modern times are seen despite the revolutions in transport with steam power, railway, and, by the early 20th century, automobiles.

Was the Black Death a one-off occurrence?

No. There have been three identified so-called ‘pandemics’. First, there was a significant international epidemic in the sixth century AD.

Second, starting with the Black Death – its deadliest attack – plague later returned to Britain in 1361 (when it affected especially younger and elderly people); 1374, and regularly until it disappeared shortly after the Great Plague of 1665.

Third, the disease broke out once more in Asia in the 1890s, and established new foci, where it is still found in animal populations today.

Will the Black Death return?

In fact, the disease has never gone away. An outbreak in Surat in India in the early 1990s caused panic across the world. The death of a herdsman in Kyrgyzstan in 2013 from bubonic plague was wildly exaggerated in the media.

Samuel Cohn is professor of medieval history at the University of Glasgow and author of Cultures of Plague: Medical Thinking at the End of the Renaissance (Oxford University Press, 2010)

Tom Beaumont James is a professor of archaeology and history at the University of Winchester

This article is an amalgamation of two articles published on History Extra in October 2015 and November 2014

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