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Popular Science Monthly/Volume 51/May 1897/The Bubonic Plague



THOSE twin monsters of human misery, Famine and Disease, are now holding high carnival in India. Death follows in their wake and gathers in a rich harvest. Appeals to the charitable of the world are being made, and the civilized nations of Europe and America are looking apprehensively toward the East. The great plague, which has confined its ravages for the most part to certain limited districts of Asia for the past two hundred years, seems to have grown strong enough to threaten to take a journey abroad. The black death has unfurled its banner in the face of modern civilization. For a period of more than a thousand years this disease once held dominion over Europe. The story of the horrors of the fourteenth and seventeenth centuries has seemed a history of a past so remote that it has been nearly forgotten save by those especially interested in the progress of medicine. Is history to repeat itself in this form of human suffering? What is the bubonic plague? Do we know anything of its specific cause, of its methods of invasion, of the means necessary to combat it? These are questions which I have thought might at this time be of more than passing interest.

Oribasius was physician and friend of Julian the Apostate, and lived in the fourth century of our era. He wrote a medical encyclopædia, composed principally of extracts from older medical authors. This encyclopædia remained unknown in the Vatican Library until the early part of the present century, when it was discovered by that indefatigable student of old manuscripts, Cardinal Mai. In the forty-fourth book of this collection there is a note from Rufus, who states that the physicians of the time of Dionysius were acquainted with a disease which is described as "Pestilentes bubones maxime letales et acuti, qui maxime circum Libyam et Egyptum et Syriam observantur." There follows a description of this disease sufficiently accurate to leave no doubt that it was identical with the bubonic plague. Now, this Dionysius lived about three hundred years before Christ. There is therefore no doubt that the plague has been known for more than two thousand years.

The next authentic account of the plague is that of the epidemic of the sixth century. The disease at this time was first recognized in Lower Egypt, from which country it extended into Europe by two routes. It was brought from the north coast of Africa, and it also extended through Palestine and Syria, and by this way into Europe. This disease became pandemic and spread, according to the chroniclers of the time, to the "ends of the habitable world." It prevailed in an active form for about sixty years, showing great virulence in certain localities. According to Warnefrid, "it depopulated towns, turned the country into a desert, and made the habitations of men to become the haunts of wild beasts." Hirsch says: "It is impossible to decide whether this outbreak of plague in the second half of the sixth century was the first general diffusion of the disease on European soil, or whether it had been epidemic there before, and if so, to what extent. What is certain is that this outbreak gave it firm hold in Europe, and that it kept its dominion there for more than a thousand years."

It is an interesting fact that this pandemic occurred during the reign of Justinian the Great, the most illustrious emperor of the Eastern Roman Empire. This man, who did so great a service to the world in the codification of the Roman laws, seems to have been both wise and unwise. He is said to have been so filled with Christian ardor that he forcibly baptized more than seventy thousand pagans in Asia Minor alone; and yet he was a pagan by birth, and there is reason for believing that he died a pagan. He is known as the great legislator, and yet he oppressed the people to the verge of starvation by the imposition of unjust taxation, and by granting monopolistic privileges to a few. On one side he instituted just reforms and on the other he fell into reckless and extravagant expenditures. He built the great cathedral of St. Sophia, now a Turkish mosque and one of the architectural wonders of the world, with a treasury filled with the sighs and tears of his overtaxed subjects. I mention these facts in order to show that the spread of the plague occurred at a time when the masses of the people were oppressed by wrong and broken by burdens too heavy to carry.

From the time of Justinian on, for more than ten centuries, as has been stated, the plague raged, sometimes with more, sometimes with less, severity, in Europe. The historians of the time generally content themselves with a statement of its most violent outbursts and an enumeration of its victims. The numbers given must, in many instances at least, be gross exaggerations. It is possible, also, that other diseases, especially smallpox, were included in these accounts, but, as Hirsch states, the bubonic plague takes at any rate a foremost place among the great epidemic diseases of those times.

The same author says: "There is only one of the epidemics of the plague in the middle ages that has arrested the attention of the chroniclers, poets, and physicians of those days; and that interest was awakened by the enormous diffusion that it reached over the whole of the then known world, by its victims reckoned in millions, and by the shock to the framework of society which it brought with it and left behind it. This disastrous pestilence, known everywhere under the name of black death, as one of the great events of the world's history, has fixed the attention of writers in a high degree, and has been thought worthy to be painted in minutest details and in the most vivid colors."

Several accounts of the plague of the fourteenth century have become classical. Among them I may mention that of Boccaccio, which begins as follows: "In the year, then, of the fruitful nativity of our Lord, 1348, there happened at Florence, the fairest city in all Italy, a most terrible plague; which, whether owing to the influence of the planets, or that it was sent from God as a just punishment for our sins, had broken out some years before in the Levant"; and concludes thus: "Between March and July following it is supposed, and made pretty certain, that upward of a hundred thousand souls perished in the city only; whereas, before that calamity, it was not supposed to have contained so many inhabitants. What.magnificent dwellings, what noble palaces were then depopulated to the last person! What families extinct! What riches and vast possessions left, and no known heir to inherit! What numbers of both sexes in the prime and vigor of youth, whom in the morning, neither Galen, Hippocrates, nor Æsculapius himself but would have declared in perfect health—after dining heartily with their friends here, have supped with their departed friends in the other world!"

This epidemic, like all others of the plague, spread from the East to the West. It prevailed in the Crimea in 1346, reached Constantinople in 1347, and, as we have seen by this quotation from Boccaccio, began its devastations in Florence in 1348, and by the beginning of 1350 it had spread all over the continent of Europe and the adjacent islands. Hecker places the number of deaths from this epidemic at no less than twenty-five millions, or about one fourth of the inhabitants of that part of the globe at the time. Hirsch believes that this estimate was not too high.

The history of the fifteenth century is dotted with notes of local epidemics, and at this time physicians begin to report more accurately and in greater detail the characteristic symptoms and the course of the disease. It was at this time that exanthematic typhus was recognized as a distinct disease, and distinguished from the other pests of the medical profession.

During the sixteenth and seventeenth centuries the bubonic plague seems to have prevailed as an endemic disease in Europe.

There was scarcely a year during these two centuries that this disease did not assume alarming proportions at some place on that continent. The last visitation in England is known as the Great Plague in London, which occurred in 1665. This has been very graphically described by De Foe, and has been the basis of the thrilling story by Ainsworth entitled Old St. Paul. During the last quarter of the seventeenth century the plague seems to have gradually receded toward the East.

During the eighteenth century it repeatedly threatened to extend over Europe, but seldom reached farther than Turkey and the immediately adjacent territory to the north. However, there were as many as eighteen distinct and severe epidemics in Constantinople during that time.

Up to 1841 the plague occasionally became epidemic in the Balkan Peninsula, and there was an outbreak in the province of Astrakhan in the winter of 1878-'79. Since the last-mentioned years it has not appeared in Europe, but has continued in certain parts of Asia. In 1894, just before the beginning of the Chinese-Japanese War, it appeared in a virulent form at Hong Kong. The Japanese Government sent Kitasato and the French sent Yersin to study this disease according to the latest methods of bacteriological research. Both of these men were eminently qualified for the work of their mission, and independently each soon succeeded in isolating the specific bacillus. It is found in the fæces, in the contents of the swollen glands, and in the blood. It consists of rods with rounded ends, which take stains more markedly at the extremities than in the middle. Sometimes the germ seems to be surrounded with a capsule. In beef tea it grows in chains and forms a viscid deposit on the walls and bottom of the tube. It also grows on blood-serum and agar. On potatoes it does not grow at ordinary temperature and only feebly at 38° C. It shows but little motility and grows most abundantly at the temperature of the body.

The bacillus is pathogenic to guinea pigs, rabbits, rats, and mice, and it is stated that at times of the existence of an epidemic of the plague some of these animals acquire the disease, and it has been suggested that they may act as agents in its spread. In the above-mentioned animals the first symptoms manifest themselves usually within from one to two days after inoculation. The animal becomes apathetic, the eyes are watery, the temperature rises, and death, preceded by convulsive movements, comes on within from two to five days. The tissue around the point of inoculation is inflamed and infiltrated with a bloody, gelatinous exudate. The spleen is enlarged and sometimes the lymphatic glands are swollen. The bacillus is found in the blood and in all the organs.

Mice and guinea pigs fed with pure cultures or with tissues containing the germs die with the symptoms mentioned above. Kitasato found the bacilli in a dead mouse from a plague-stricken house. He also inoculated animals with dust gathered from such houses, and one of these died with symptoms of the plague, and the bacillus was found in its body. In certain parts of Asia the disease is, according to Cantline, known as "rat plague," thus indicating an extensive infection of these animals.

Cantline makes the following statement concerning the susceptibility of rats to the disease: "On all hands rats are reported to behave peculiarly and with a wonderful constancy. Before, or it may be during an epidemic of plague, or before the individuals in any particular house in an infected locality are stricken, the rats leave their haunts and seek the interior of the house. They become careless of the presence of man, and run about in a dazed way with a peculiar limping jerk or spasm of their hind legs. They are frequently found on the bedroom floor or on the tables, but not infrequently their death is known by the putrefactive odor of their decomposition arising from beneath the flooring. So pertinent has this rat affection become, that during the epidemic in Macao in 1895 the Chinese and Portuguese left their houses when the diseased rats invaded their premises. The cause of the rats' behavior is undoubtedly disease, and the symptoms tally wonderfully with plague symptoms of man. Dr. Rennie examined them carefully in Canton, and noted the following post-mortem appearances: (1) The stomach was distended and filled with particles of food, sand, and indigestible substances, and the mucous membrane was red and inflamed toward the pyloric end; (2) the liver was much enlarged and congested, and contained ova of tænia and distoma; (3) there was congestion at the base of the lung present in about forty per cent; and (4) glandular enlargement was present in thirty per cent of those examined. There is no doubt now that the disease in the rat and man is identical. The bacillus of plague has been met with in every case of rat disease of this description when it has been searched for. The infection of the rat is raised from being a mere popular belief into one of scientific precision, and we must now accept the rat, at any rate, as one animal liable to the plague. Whether the rat is affected previously to, coincidently with, or subsequently to man being attacked is open to question. Is the disease among rats a forerunner of its outbreak in man, and, if so, are they a means of infection? These are, of course, two separate questions." Exposure of the bacillus in thin layers to the direct action of sunlight destroys it after from three to four hours, but to accomplish a like result from exposure to diffuse light as many days are necessary. The germ is killed by an exposure to a temperature of 80° C. for thirty minutes and at 100° C. within a few minutes. Spore formation has not been observed.

There is some reason for believing that there is a pseudo-bacillus of the plague as there is one of diphtheria. In his studies of the soil of the infected districts of Hong Kong, Yersin found a bacillus that resembled that obtained from persons with the disease, both morphologically and in its growth on culture media, but it was without effect upon mice and guinea pigs. He also observed great differences in virulence in the germs obtained from the sick; some of these were without effect upon the above-mentioned animals. There were, moreover, observable variations in the size of the bacilli found in the bodies of the sick and dead.

The studies of Yersin and Kitasato were interrupted by the war between China and Japan, and a much more thorough knowledge of the bacillus and the disease caused by it will probably soon be in our possession.

I will now consider some of the characteristic symptoms of the disease. It is undoubtedly a septicemia, or form of blood-poisoning. As has been stated, the bacillus is found in the blood and in all the organs. It is customary to describe the disease under two forms. The milder epidemics are known under the name of pestis minor. In this form the glands of the groins and armpits swell and either suppurate or undergo resolution. There is moderate fever, although in exceptional cases the temperature may reach 104° F. The disease usually continues from ten to twenty days, and may last for from four to eight weeks. Pestis minor sometimes precedes and at other times follows the more severe forms of the disease. The former was the case in the epidemics in Mesopotamia in 1873 to 1878, and in Astrakhan in 1878.

Foderé, as quoted by Cantline, makes the following statement concerning pestis minor: "In the Levant and in the Marseilles epidemics of 1820, cases were to be seen which were not ushered in by any alarming symptoms, and where the natural functions were undisturbed, and where buboes and carbuncles appeared without fever, or only with slight fever, or the buboes went on to a healthy suppuration more or less prompt, or even disappeared and went on to resolution without the help of art, without any inconvenience, and with a perfect integrity of all the functions. This state is comparable to benign smallpox, during which children play together and walk in the streets without any precautions, no care being taken of their treatment, and yet terminating favorably. It is the benign plague of authors, which is observed when the disease commences and when it is at its end, though it is rarely seen in the middle period, which is entirely devastating, but it is not less plague, and it no less merits the attention of physicians and magistrates."

In pestis major there is a prodromal stage, accompanied by aching in the limbs, shivering, and a high degree of nervousness. The patient seems to be unable to quickly comprehend questions. There is a staggering gait similar to that of alcoholic intoxication. There is intense headache, with thirst and great pain in the epigastrium. The eyes become red; the tongue dry, swollen, fissured, and sometimes black, and at other times covered with a thick white coat. Coma may set in and death result before there is any marked elevation of temperature. In some cases, however, the temperature may reach 107° F. during the twenty-four hours preceding death.

In the cases less rapidly fatal there are glandular swellings. These occur in the groin in about fifty per cent of the cases, in the armpits in about thirty-five per cent, and less frequently in the neck and other localities. One peculiarity of the graver form of the disease is the occurrence of stablike pains in various portions of the body. This symptom gives rise to the superstition among the ignorant that the victim is wounded by invisible arrows shot from the bow of some demon. Suppuration of the buboes with free discharge has been regarded as a favorable symptom. The skin is sometimes covered with livid petechiæ, which become very dark after death. This condition gave rise to the term black death, which has been applied to certain epidemics. Large carbuncles may form in various parts of the body, and these are regarded as a very unfavorable sign.

A highly fatal form of the disease is accompanied by hæmorrhages from the lungs. This was a noticeable feature of the pandemic of the sixteenth century, and it was also observed in the recent outbreak along the Volga. Such hæmorrhages indicate a grave form of intoxication, and have been observed in the severer forms of other acute infectious diseases, such as smallpox.

The virulent form of the plague is often very rapid in its action, sometimes destroying life in a few hours, but the majority of fatal cases terminate about the fifth day. During an epidemic at Bagdad it was said that those who lived until the seventh day were safe, but, according to Colvill, four per cent of the fatal cases terminated after the tenth day.

The mortality from the plague in its virulent form is probably as great as or greater than any other of the acute infectious diseases. In many epidemics it may be more than ninety per cent.

Hecker gives the following statement, which must be an exaggeration, concerning the mortality of the black death: "Cairo lost daily, when the plague was raging with its greatest violence, from ten to fifteen thousand. In China more than thirteen millions are said to have died. India was depopulated. In Caramania and Cæsarea none were left alive. On the roads, in the camps, in the caravansaries, unburied bodies alone were seen. Twenty-two thousand persons and most of the animals were carried off in Gaza within six weeks. Cyprus lost almost all its inhabitants, and ships without crews were often seen in the Mediterranean, as afterward in the North Sea, driving about and spreading the plague wherever they went on shore. It was reported to Pope Clement that throughout the East, probably with the exception of China, 23,840,000 people had fallen victims to the plague."

Probably the most constant pathological lesion found after death from this disease is an enlargement of the lymphatic glands. The disease may run so rapid a course that the enlargement of the glands is not observable during life, but, according to recent and competent observers, changes in these tissues will be found in the great majority of cases. This has led Cantline who studied the disease at Hong Kong in 1894, to propose for it the appellation of "malignant polyadenitis." The same authority offers the following definition: "Plague or malignant polyadenitis is an acute febrile disease of an intensely fatal nature, characterized by inflammation of the lymphatic glands, marked cerebral and vascular disturbances, and by the presence of a specific bacillus."

Geographically the plague has been known as far east as the island of Formosa, where it now prevails; as far west as Ireland; as far north as Norway; and there is no definite information concerning its extension southward in Africa. It has never been known in the western hemisphere, but this is only due to the fact that up to the present time there has been no opportunity of its importation to this half of the world.

In this connection the following quotation from Hecker may be of interest: "The inhabitants of Iceland and Greenland found in the coldness of their inhospitable climate no protection against the southern enemy who had penetrated to them from happier countries. The plague caused great havoc among them. Nature made no allowance for their constant warfare with the elements and the parsimony with which she meted out to them the enjoyments of life. In Denmark and Norway, however, people were so occupied with their own misery that the accustomed voyages to Greenland ceased. Towering icebergs formed at the same time on the coast of east Greenland, in consequence of the general concussion of the earth's organism, and no mortal from that time forward has ever seen that shore or its inhabitants."

There is no known racial immunity to this disease. It is alike fatal to Mongolians, Africans, and Europeans. It has prevailed in the marshes along the Euphrates and on the Himalayas; in densely populated cities and in sparsely settled rural districts; on the sands of Egypt and amid the snows of Norway.

Climate and season have been studied in order to establish between them and the plague a causal relationship. Epidemics have followed prolonged droughts, and have prevailed during rainy seasons. The wind may blow where it listeth, but the bacillus heedeth it not. The epidemic at Hong Kong in 1894 appeared after a prolonged season of dry weather. Rain was anxiously looked for—probably prayed for. It was said. All will be well when the rain comes. At last the rain did come, and with it the disease seemed to be refreshed and the number of deaths was multiplied. The attempt to find in meteorological conditions a cause for our ills is a relic of the superstition of ages when it was believed that disease was sent from heaven to afflict man for his sins, and was due to the anger of the gods.

Overcrowding is undoubtedly a factor in the distribution of this disease, as it is of all other infectious diseases, simply because it renders transmission of the germ from one to the other more speedy and certain; but that the disease can be due to overcrowding is, in the present state of our knowledge, an absurdity.

Poverty and famine are factors in the propagation of the disease. Want of proper food renders the individual more susceptible. This has been demonstrated in case of more than one infectious disease by experiments upon the lower animals. Privation has always been associated with the most notable outbreaks of the plagues. As stated in the beginning of this paper, famine and disease are twin brothers, inseparable. Where one of them dwells there the other may be found. This is undoubtedly the reason why this disease has always found a home in the Levantine. Cantline says: "In the densely packed cities of Asia the poor exist forever on the fringe of destitution, and the least rise in the price of food brings scarcity, so that the term, 'the poor man's plague,' holds good for all time."

There has been much written concerning the period of incubation of this disease, but necessarily all is indefinite. Because a well man comes in contact with a sick one on a certain day, and manifests the first symptoms of the disease ten days later, does not prove that the period of incubation is ten days. The well man may have carried on his person the bacillus from the sick-room, and any time subsequent thereto it may have been introduced into the body. All that is said about the period of incubation of the infectious disease is based on the old theory—long since exploded—that the well man breathes in the miasm at the time of his coming into the presence of the sick one, while the truth is he may carry the germ under his finger nails or elsewhere about him, and there is no telling when it may first find its way into his body. We can determine the period of incubation in the lower animals by inoculation, and here we know that it varies greatly with the method of inoculation, the virulence of the germ, the number of germs introduced, and the susceptibility of the animal. All that may be said about the period of incubation in man is of but little value. The same is largely true concerning the extent to which the disease is contagious. In the epidemic of 1835 in Egypt only one of the French physicians who attended the sick contracted the disease. Bulard, who did not believe the plague contagious, wore for two days a shirt taken from the body of a dead man. He remained well, and thought that by this he had demonstrated the truth of his theory. Such experiments demonstrate nothing. There is no evidence that any of the bacilli were on the garment, or that, if they were, they were introduced into his body. During the epidemic in Hong Kong, fifteen European physicians and a number of Chinese medical students cared for the sick in the hospital, and none acquired the disease. This only shows that with care and cleanliness the sick may be attended without danger of infection of the attendants. Hundreds of bacteriologists in laboratories are daily handling the most virulent cultures of the diphtheria bacillus, and the first case of infection from this source has yet to be reported. This does not prove that these bacilli are not pathogenic to man, or that these men are insusceptible to the disease. Because an expert handles the most venomous serpents without being bitten, does not prove that the bite of these reptiles is harmless.

The exaggerated idea of the contagiousness of the plague held by some of the older writers is exemplified in a graphic way by the following quotation from Hecker: "Every spot which the sick had touched, their breath, their clothes, spread the contagion; and, as in all other places, the attendants and friends who were either blind to their danger or heroically despised it, fell a sacrifice to their sympathy. Even the eyes of the patient were considered as a source of contagion which had the power of acting at a distance, whether on account of their unwonted luster or the distortion which they always suffer in plague, or whether in conformity with an ancient notion, according to which the sight was considered as the bearer of demoniacal enchantment.

The plagues of the middle ages were undoubtedly spread by the processions of the Brotherhood of the Cross. These fanatics went, sometimes in great numbers, from place to place, praying for the sins of the world, and scourging themselves with leathern straps armed with points of iron.

The horrors of the plague of the fourteenth century have been depicted by Hecker and others. The moral depravity brought to light by this great epidemic is hardly credible. Many believed themselves poisoned, and suspicion fell upon the Jews, who have so often been treated by Christians with barbaric cruelty. Under the torture confessions were made, and then began the wholesale slaughter of the children of Abraham. In Basle, the whole Jewish population was brought together in a wooden building constructed for the purpose and burned. "At Strasburg two thousand Jews were burned alive in their own burial ground. . . . At Eslingen the whole Jewish community burned themselves in their synagogue; and mothers were often seen throwing their children on the pile to prevent their being baptized, and then precipitating themselves into the flames. . . . In all the countries on the Rhine these cruelties continued to be perpetrated during the succeeding months; and after quiet was in some degree restored, the people thought to render an acceptable service to God by taking the bricks of the destroyed dwellings and the tombstones of the Jews to repair churches and to erect belfries."

Knowing, as we now do, the specific cause of the plague, we may easily predicate the modes of its distribution. Anything that carries the bacillus may be an agent of its transmission from one person to another, or from one country to another. It is needless to dwell upon this point.

Is there danger of the plague being imported to this country? Yes, there is danger, but this being foreseen may be easily avoided. Thorough inspection of persons and disinfection of things from infected districts will keep the disease out of Europe and America. Only by the most gross carelessness could the plague be permitted to enter either of these continents. The method of disinfecting the mails from the Orient, as practiced by the English, is wholly inadequate, and the American authorities should redisinfect all such matter coming from the infected districts of India.


On the occasion of the opening of the Davy Faraday Research Laboratory at the Royal Institution, London, Dr. Ludwig Mond observed that if Great Britain had distinguished itself in one way more than another in that glorious rivalry with other nations for extending our knowledge of natural phenomena and our power over the forces of Nature, it had been by the large number of contributors to our knowledge who on the Continent would be called amateurs in science—men who devoted their lives to the study and advancement of science from pure love of the subject. He need only instance the names of Cavendish, Joule, and Darwin to say that they included men of the very highest rank.