Apocalypse Then: A History of Plague During the 1300's, a mysterious and deadly disease wiped out a third of Europe—roughly 20 million people. By Robin Netherton "How will posterity believe that there has been a time, without lightnings of heaven or fires of earth, without wars or other visible slaughter, [when] well nigh the whole world has been left without inhabitants? When before has been seen houses left vacant, cities deserted, fields too small for the dead, and a fearful and universal solitude over the whole earth?" The images of many terrible diseases haunt modern memory, but the one described by the Italian poet Petrarch was worst of all: deadlier than smallpox, more infectious than polio, more mysterious than AIDS. While all these illnesses have been called plagues, only one disease bears the name plague as its own. The Black Death When the disease swept like a brush fire across Europe in the 1300's, people called it by other names: the Great Mortality, the Pestilence, or simply, the Death. Later writers referred to that epidemic as the Black Death, perhaps recalling the black spots that covered victims' skin. In only four years, from 1347 to 1351, plague killed as many as one of every three people in Europe, devastating families, communities, and society. Since then, scholars have routinely acknowledged the epidemic as the greatest single disaster in European history. Looking back over a safe distance of 600 years, scientists find it easy to see how the epidemic cut its deadly path through Europe. They now know that plague is caused by bacteria—tiny one-celled organisms that were unknown to medieval physicians—and that the plague-causing bacteria normally infect rats and other rodents. They also know that fleas can transmit the bacteria to people by leaping onto—and biting—warm human skin after their rat hosts die. But medieval people never suspected that victims were infected by the bites of common fleas. Nor did they realize that the disease owed its swift spread to the movement of flea-bearing rats from town to town. Perhaps most terrifying of all, people had no way of knowing when—or even if—the mysterious pestilence would end. Even though that devastating outbreak finally did subside, plague is still with us. The disease strikes hundreds of people around the world each year, including some in the United States. Although plague today is hardly harmless, it can now be controlled and even cured. Yersinia pestis—the bacterium that causes plague The plague-causing bacterium, Yersinia pestis, is named after French bacteriologist Alexandre Yersin, one of the scientists who discovered it in 1894. At least 200 species of rodents carry Yersinia pestis today, including many types of rats, mice, squirrels, prairie dogs, gophers, and chipmunks. The bacteria move from one rodent to another by riding in the guts of fleas that live on animal blood. When one rodent dies of plague, its fleas hop to another, injecting the bacteria into the new host when they feed. Plague does not automatically destroy every animal colony it infects, however. Rodents can often tolerate some plague bacteria in their systems without falling ill, and some rodents survive the disease and become immune (permanently protected against a disease). Most of the time, in fact, the disease stays within closed communities of animals, as the populations of rodents, fleas, and bacteria rise and fall in response to one another. When a disease becomes established in a community, it is said to be endemic. Yersinia pestis has been endemic among wild rodents in various parts of the world for centuries. Sometimes, however, for reasons that scientists do not completely understand, an outbreak of plague will kill off an entire rodent colony. When a hungry flea can find no rodents left to bite, it seeks other sources of food—which might include human beings. Following the spread of the Black Death The bacteria responsible for the Black Death most likely came from central Asia, though scholars still debate the exact origin of that outbreak. In the mid-1340's, the bacteria reached the caravan route that ran between China and Europe—perhaps when trappers picked up dead animals for their furs. Via this busy trade route, plague could spread west to the Black Sea. There, at the port city of Caffa (now Feodosiya in the Soviet Union), Italian merchant ships docked to pick up silks and spices from the Orient. The ships were a haven for black rats, which hid by day and scavenged by night. In a crowded port, the rats could easily leap from ship to ship or climb ropes from ship to shore. A single infected rat might carry dozens of fleas, each of which could bear millions of bacteria. And the fleas themselves could live amid bales of fur or cloth for weeks without a meal, waiting to leap upon a new warm-blooded body. Sicily—then Marseille in France Because surviving records are unclear, historians cannot be sure exactly when plague reached various Asian cities. They do know that by late 1347, the disease had struck the chain of ports along the shipping route from the Black Sea to Italy. It entered Europe in October when it struck Messina, the chief port of the Mediterranean island of Sicily. The Sicilians had heard rumors of a dreadful pestilence sweeping the Orient. Realizing that the new disease might be this Eastern scourge, Messina's townspeople closed the port. Their efforts came too late: The entire island was soon infected. Meanwhile, the ships—and the plague—proceeded to other port cities, crossing the Mediterranean to Egypt, northern Africa, and Spain. The epidemic reached Marseille, in southern France, in January 1348. Within a year, it had swept across France by land, and ships carrying French wine north to England carried infected rats as well. English wool merchants probably transported plague to Scandinavia in 1349. It swept through Denmark and Germany in 1350 and touched Poland in 1351 before reentering central Asia from the west. A hideous, repulsive death Wherever the disease traveled, it brought a hideous, repulsive death. Written accounts tell of shivering fits, bloody vomit, and an intolerable stench radiating from a victim's breath, body, and wastes. Other symptoms were stranger. Italian author Giovanni Boccaccio (1313?-1375), who lived at the time of the epidemic, described the disease's hallmarks: "It began both in men and women with certain swellings in the groin or under the armpit. They grew to the size of a small apple or an egg.... In a short space of time these tumors spread from the two parts named to all over the body. Soon after this the symptoms changed and black or purple spots appeared on the arms or thighs or elsewhere on the body, sometimes a few large ones, sometimes many little ones. These spots were a certain sign of death." Gui de Chauliac, then physician to the pope, noted that while the illness Boccaccio described usually caused death in five days, some people recovered—as Gui himself did. But he also recognized a more deadly form, with "continuous fever and spitting of blood," which invariably killed in three days. Other writings suggest yet a third form that struck so suddenly—and without warning symptoms—that people who went to bed healthy were found dead in the morning. Three forms of plague The medieval descriptions reflect quite clearly the three forms of plague known today: bubonic, pneumonic, and septicemic. Bubonic and septicemic plague most commonly result from flea bites, which inject Yersinia pestis directly into the body. These forms of plague can also be acquired by absorbing body fluids, such as blood or saliva, of an infected person through a break in the skin. Pneumonic plague is contracted from coughing plague victims whose lungs are infected. Bubonic plague Bubonic plague, the predominant form of the disease, takes its name from the lumps it causes in the neck, armpits, or—most often—the groin. Medieval doctors called the lumps buboes, from the Greek word for groin, boubon. A bubo is actually a mass of swollen lymph nodes, small bean-shaped structures clustered in bunches in the body. Fluids that bathe the body's cells circulate through the lymph nodes, which filter out harmful microorganisms. The presence of an infection causes the lymph nodes to swell. When Yersinia pestis enters the body through a bite or break in the skin, it incubates for an average of two to five days before causing symptoms. Then come headache and weakness, followed by fever, aches, chills, rapid pulse, and vomiting. The cluster of lymph nodes closest to the site of infection swells to an extreme, forming the first bubo. Infection through the skin of the torso, arm, or head can cause buboes in the armpits or throat. But because fleas usually bite on the legs, the buboes most often appear in the groin. The lumps can grow up to 2 inches (5 centimeters) across. After a few days, the swollen nodes may burst, breaking the skin, and drain. As the plague bacteria multiply in the body, the patient becomes listless and uncoordinated and may have trouble walking and talking. The bacteria often invade the lungs, causing pneumonia. Bacterial toxins (poisonous wastes) in the bloodstream produce clotting. The clots cause blood vessels to burst under the skin, creating the disease's characteristic dark blotches. Finally, the toxins attack nerve cells, producing agonizing pain, delirium, and despair. Death occurs in 60 to 80 per cent of untreated cases, usually within a week of the first symptoms. (By comparison, untreated smallpox killed up to 20 per cent of those it infected.) Pneumonic plague Pneumonic plague develops when a person inhales the tiny, infected droplets coughed up by a bubonic plague patient who has pneumonia. Contracted this way, the bacteria invade the victim's lungs immediately, causing rapidly progressing pneumonia marked by high fever, chills, headache, and a cough that brings up blood. The patient's coughed-up fluids can infect others in turn. If untreated, pneumonic plague usually kills within two or three days. Septicemic plague Septicemic plague, which is almost always fatal, occurs when the bacteria overwhelm the bloodstream instead of congregating in the lymph nodes. The bacteria and their toxins invade and destroy tissues throughout the body, and the victim dies within a day or less. Although septicemic plague generally kills before a diagnosis can be made, doctors today can cure bubonic and some pneumonic cases by administering antibiotic drugs as soon as they suspect plague. Delay can be fatal: With enough of a head start, the bacteria can fill the blood with so much toxin that the patient may die even after drug treatment controls the bacteria themselves. Medieval physicians helpless against the disease Medieval doctors had no miracle drugs, however, and their treatments—which typically involved bloodletting, enemas, and a bland diet—proved powerless against the plague. Unaware of the true cause of the disease, some theorized that earthquakes or unseasonable winds had poisoned the air. Others blamed cataclysms in the Orient—rains of frogs and serpents, massive clouds of foul smoke—that were rumored to have preceded the plague. Scholars at the University of Paris cited a conjunction of the planets Saturn, Mars, and Jupiter on March 20, 1345, as having caused "pernicious corruption of the surrounding air." Spiritual leaders saw a different reason for the plague: punishment for human sins. Yet prayer, penance, fasting, and other religious observances did nothing to stop the epidemic. Some people, observing that priests were struck down as often as others, abandoned the organized church for alternative cults. Many chroniclers describe cults of flagellants—groups who traveled from town to town, publicly whipping themselves in bizarre religious ceremonies. Seeking a cause—or scapegoat Because no other means of transmission was apparent, many people readily accepted the explanation that the air itself had become contaminated. They wore masks to avoid evil vapors, carried herbs and perfumes to nullify them, or inhaled the stench from public latrines to drive the tainted air from their lungs. The pope, at his palace in Avignon in southern France, sat between two huge fires meant to purify the air. Elsewhere, people banished or burned foreigners, Gypsies, beggars, or lepers for supposedly bringing the disease. Most often, the blame fell on the Jews—even though plague struck them as well—and many thousands of Jews were slaughtered throughout Europe. Some people, faced with seemingly certain death, embraced wild living, drinking, gambling, and merrymaking. Most, however, closed themselves in their homes, marking crosses on the doors in the hope they would be spared. Many towns shut their gates to travelers and traders. In the Italian city of Milan, the archbishop ordered townspeople to brick up victims' houses, with any remaining occupants, sick or not, left inside. Such efforts at quarantine invariably failed, however, because rats still ran freely, and unnoticed, from house to house. The country versus the city Ultimately, people fled, seeking refuge in regions yet untouched by plague. Many of those who ran merely carried the disease with them, infecting new communities. Those who left the cities for rural mountains seem to have survived in greater numbers, probably because rats and fleas dislike cool, dry climates. Yet survivors credited any of a hundred other rituals: bathing, or avoiding bathing; eating strange concoctions of herbs, or fasting; sleeping on one side or the other, or only sleeping at certain hours. Cities, crowded and easily infected, suffered the worst losses. Major cities such as Paris and Rome saw hundreds of deaths daily at the epidemic's height. Oppressed by the ceaseless tolling of funeral bells, authorities in many cities forbade their ringing, along with large funerals or mourning clothes. Coping with death on a massive scale As the death count rose, so did the piles of rotting corpses. Before long, the dead began to overwhelm the living. Bodies were dragged out to doorsteps each morning, alongside the piles of uncarted garbage. Convicted criminals, country laborers, or members of religious orders hauled the remains away until they, too, died. When cemeteries filled, officials opened nearby fields for mass graves. In fact, the scene of a foul pit of ravaged or burning bodies, tended by doomed workers, became so universal a symbol of terror and despair that preachers and painters for centuries afterward were to summon it up as an image of hell. Impact of the Black Death on society Along with funeral customs, other trappings of civilized life were shed during the months and years of plague. An English bishop complained in a letter of 1349 about the lack of priests to hear confession or administer last rites for plague victims. Civil courts and meetings of governmental bodies were suspended. The streets were left to thieves, "for, like other men, the ministers and the executors of the laws were all dead or sick or shut up with their families," Boccaccio wrote. In retrospect, the time of chaos in any one place was brief. A village might have suffered for six months, a large city for a year or two, before the plague moved on. But during that time, industry and trade all but ceased as many laborers lay sick or dying and the rest avoided contact with others. In Siena, Italy, work on a great cathedral halted, never to be resumed. Mortality may well have reached 90 to 100 per cent in some communities, such as monasteries where many men shared crowded dormitories infested with rats. But the death rate throughout Europe was certainly far less. Estimates today, based on such evidence as wills and tax records, vary widely by region. Overall, modern scholars generally come up with the same rough estimate recorded by the French historian Jean Froissart (1337-1410): "At least a third of all the people" of Europe—perhaps 20 million or more—died in the Black Death. Recurring epidemics Even after the initial wave burned itself out in 1352, plague reappeared in lesser epidemics every 10 years or so for the rest of the 1300's. In England, the second wave, in 1361, was called the "Pestilence of the Children" because it proved especially fatal to the young. That is probably because the adults who had survived the earlier outbreak of the disease were immune, while children born after it had no such protection. After 1400 or so, plague's recurrences, while common, were far less severe and more localized. Experts suggest that by this time the European populations of rats, fleas, and Yersinia pestis had achieved some sort of balance. Disruption of the social order But even as the plague moved toward a biological balance among animals, it destroyed the social balance among human beings. In Europe, a major effect was economic upheaval. The deaths of so many people produced an abundance of land and a shortage of labor, upsetting the old order. For example, peasants were able to demand higher wages and to take control of farms whose owners had died of plague, breaking down the centuries-old class distinction between laborers and landowners. At the same time, the sudden deaths of so many of Europe's established scholars left a large gap in the world of learning, eventually filled by young thinkers with new ideas. And a disillusioned public began to question the overarching power of the medieval Church and the obedience it demanded. Defiance soon turned to revolt against Church and civil authorities. During the English Peasants' Revolt of 1381, for example, mobs stormed London to protest laws that protected the class structure. Many historians believe that the changes provoked by the Black Death laid the groundwork for the social revolutions of the next two centuries, including both the Protestant Reformation and the Renaissance. Plague epidemics other than the Black Death and its aftermath The Black Death was without doubt plague's most devastating appearance. But it was by no means its last—or even its first. Various epidemics called "plagues" have been recorded since ancient times, but historians believe bubonic plague made its first major showing in the mid-500's, when an epidemic crippled the city of Constantinople (now Istanbul, Turkey), capital of the Byzantine Empire. Plague recurred periodically throughout the Mediterranean region before subsiding in the 700's. After its reappearance in the 1300's, however, plague remained entrenched for four centuries before disappearing completely from western Europe around 1720. In China in 1855, soldiers carried plague out of an isolated area where it was endemic, leading to a series of outbreaks throughout the Chinese interior. The disease gained international attention only when it reached the populous centers of Canton and Hong Kong in 1894. From there, the bacteria were transported by steamship to previously untouched areas, including North America. The first U.S. outbreak—in 1900 in San Francisco—was quickly contained, but the bacteria established a home in California's rodent communities. By then, however, scientists had discovered Yersinia pestis and identified its means of infection. Plague in today's world Today, plague is found in every part of the world except Australia and the islands nearby and western Europe. More than 80 per cent of reported cases occur in Africa, mostly in Kenya, Uganda, Tanzania, and Zaire, and analysts believe many more African cases go unreported. In South America, plague cases regularly are reported in Brazil, Ecuador, Peru, and Bolivia. In Asia, plague has appeared recently in Indonesia, Burma, Vietnam, and occasionally China. Health experts know that plague is endemic among rodents in the Soviet Union, but no human cases have officially been reported there in many years. Scientists are still studying why plague no longer exists in western Europe. One current theory stems from the discovery of another strain of Yersinia bacteria there. This strain does not kill its host animals but does seem to make them immune to the deadlier Yersinia pestis. Scientists suspect such milder strains may have displaced the plague bacterium—not only in Europe, but also in the eastern United States, where plague is unknown. The American Southwest Plague is well established, however, in host animals in the American Southwest. More than half of all U.S. cases occur in New Mexico, where plague-carrying rodents, especially ground squirrels, are plentiful. Most other U.S. cases are contracted in Arizona, California, and Colorado. The number of human cases peaks every five to eight years, reflecting cycles of plague in animal populations. The most recent peak was in 1983, with 40 cases and 6 deaths. Since then, the numbers have gradually fallen, with only 1 case reported in 1990—a nonfatal infection contracted in Colorado. Human infection depends in part on the presence of the right kind of flea. To infect human beings with plague, fleas must be able to carry Yersinia pestis from host to host, and they must be willing to bite people. The species of fleas that live on California ground squirrels and rock squirrels meet both these criteria, but most other species of American fleas do not. The fleas that normally bite dogs and cats, for example, cannot transmit plague bacteria. Even so, a household pet may occasionally pick up an infected rodent flea and pass it to a human being. People can also catch plague by handling an infected animal. Hunters of ground squirrels, rabbits, and similar game, for example, can contract the disease if an infected animal's bodily fluids enter through a break in the skin. And because cats can contract plague by eating an infected rodent, cat owners sometimes become infected by the saliva or blood of their sick pet. Dogs rarely become ill from plague. Plague curable when diagnosed early Plague is curable only if treated early with streptomycin or certain other antibiotics, so those who catch it are most at risk if diagnosis is delayed. And because plague is so rare, doctors outside plague-endemic areas often do not recognize it at once. Plague deaths are thus most common among travelers who become infected in the Southwest or a foreign country and fall ill after returning home. Why a new epidemic is unlikely Even when an unwary traveler carries the disease to a city, however, there's little danger of it spreading like the epidemics of old. Villagewide outbreaks do occur in underdeveloped countries, often because medical treatment does not arrive in time to prevent the first victim from developing pneumonia and infecting others. But U.S. cities are unlikely to experience an epidemic of plague for several reasons. First, Americans rarely live in close quarters with the large numbers of rodents needed to spread the disease and cause an epidemic. And fleas that transmit the bacteria from rodents to people are not abundant in North America. Second, plague is rarely transmitted from one human being to another in the United States. Patients are generally diagnosed early and monitored closely to avoid contagion. And while fleas whose host of choice is people are an important means of human-to-human transmission in some countries, such fleas are not generally found among Americans. Yet health officials still fear that someone will return from a trip with plague and develop secondary pneumonia, infecting both family and medical staff before a diagnosis is made. Says Allan Barnes, a research biologist who directs the plague laboratory at the federal Centers for Disease Control (CDC) in Fort Collins, Colo.: "We still worry about a plague pneumonia epidemic, even though the last time that happened in this country was 1924." About 40 people in Los Angeles contracted plague during that outbreak. And because antibiotic treatment was not yet known, nearly all died. Vaccine and other preventive measures A vaccine for plague exists, but because shots must be repeated every few months, it is given only to people at high risk of contracting plague. These include certain animal control workers, laboratory researchers working with plague, travelers to plague-ridden areas, and some military personnel. Preventive measures instead focus on monitoring animal populations and educating the public. In areas where plague is endemic, officials test dead rodents for the disease and spray rodent holes with insecticide to control fleas. Area residents are encouraged to report dead wild rodents. And the CDC monitors the nation's plague cases and informs doctors in plague-endemic areas of animal epidemics that might endanger people. In the midst of the Black Death, the poet Petrarch envisioned a time in the distant future when the story of that epidemic would seem an unbelievable exaggeration. "Oh, happy posterity," he wrote, "which will not experience such abysmal woe and will look upon our testimony as a fable!" His prediction has proved close to the truth. While plague is still with us, scientists now understand its workings and know how to prevent its spread. Only accounts of its terrible history remind us of the devastation it once inflicted. The author: Robin Netherton is a free-lance writer and editor.