[From Causes of Consumption, 1899]
That phthisis is a contagious disease, has long been held in Southern Europe, especially in Italy, Spain, and Portugal, both by the laity and the great majority of the medical profession. In Rome, and in Italy generally, the people are careful to conform to a police regulation which prescribes the burning of everything used by phthisical people. 1 It was for this reason that the greatest physicians of that country, among whom may be mentioned Morgani,2 Valsalva, and Sarconi,3refused to make the post-mortem examination of phthisical persons. In that country it was even believed that in tuberculosis, as with leprosy among the Jews, the virulent matter was communicated through the walls of houses. Impressed with this idea, the Italians abstain, often for a whole year, from inhabiting a house in which a phthisical patient has died.
In Portugal, also, the beds and clothing of phthisical people are destroyed.
The belief in the communicability of phthisis caused Galen himself to send consumptive patients to Pompeii, to inhale the sulphurous volcanic exhalations. A similar belief has been held by Van Swieten, Morton, and Baum&, in early days, and more recently by Laennec, Bowditch, Budd, de Mussy, and Weber.
On the other hand it has generally been held in the north of Europe, that the disease is of a non-contagious character. England has only recently begun to give attention to this serious question, for in a leader in the " Lancet" for November, 1878, under the heading " Experience on the Contagion of Phthisis," we read, " The remarkable instances now and again seen in which persons, without hereditary tendency to phthisis, become phthisical after long-continued attendance on sufferers from the disease, have suggested to many physicians the idea that phthisis is contagious. If there be such con tagion, the mechanism has been supposed to be the inhalation, with the breath, of fine particles of tubercular sputum, atomised into the air by the patients cough."
Pidoux, of France, who had exceptional opportunities of seeing vast numbers of patients suffering from phthisis, said he had never come across a single case that he could in any way account for by contagion.
Sir Thomas Watson thus expresses himself on this subject, " Is phthisis contagious ? No ; I verily believe not. A diathesis is not communicable from person to person, neither can the disease be easily (if at all) generated in a sound constitution. Nor is it ever imparted, in my opinion, by one scrofulous individual to another."
Dr. Wm. Budd, of Bristol, long ago promulgated the view that phthisis was a disease strictly analogous to the ordinary eruptive fevers in everything but the slowness of its progress ; that, among Europeon populations, tuberculous disease had undergone mitigation of its original severity by long prevalence, but he entertained no doubt of its eminently contagious character. Drs. Sanderson and Wilson-Fox have done much to encourage a belief in the theory of contagion, but it was not until 1882 that this belief was put upon a firm basis, when Koch proved that consumption and all tubercular disease was caused by a living organism now known as the tubercle bacillus. He went further than this, and proved indisputably the communicability of this disease by experiment. Granted that phthisis is a communicable disease, the question arises: In what way is it carried ?
Is it carried by the breath ?
In order to be conveyed thus, it is absolutely necessary that the actual tubercle bacillus should be conveyed bv the expired air from the lungs of the tuberculous subject.
In 188; Dr. Heron performed some simple experiments in order to test this question Six hospital patients, far gone in consumption, were directed to breathe with usual expiration, with forced expiration, and to cough, into test tubes. Each patient used one tube for all three acts. By means of Ehrlich's test and the microscope, he found a few tubercle bacilli in two of the tubes. It was of course impossible to say which of these three acts of expiration was responsible for the conveyance of the bacilli, although it was very natural to suppose that small particles of saliva might easily be the vehicle during the act of coughing. Several years later another set of experiments was carried out by Dr. Heron, which we will describe in his own words. " During last summer (1889) my colleague, Dr. Wethered, kindly supplied me with a dozen sterilized test tubes, plugged with cotton wool in the usual way. The object I had in view was to use these tubes for the same purpose for which I had used the others in 1883. Before carrying out the experiments I ascertained, by placing a solution of lime in test tubes, similar to those I was going to use, that the breath in the conditions laid down for the experiments would go to the bottom of the test tubes. The conditions of the experiments were- that the patients selected should send expired air down these tubes in three different ways, viz., by ordinary expiration, by slightly forced expiration, and by coughing. In the observa tions made with the tubes containing lime-water, it was found that a white cloud appeared in the water when the tube was breathed into, in each of these three ways-showing, of course, that the breath reached the level of the lime-water which was about an inch deep. Four hospital patients used the sterilized tubes in the three ways described, one tube for each act of expiration. At my request, Dr. Wethered kindly examined six of these tubes, and I examined the other six. We did not find tubercle bacilli in any of them."
Dr. Heron then proceeded to carry out a number of experiments with regard to the coughing of consumptive patients. Clean sheets of paper were held before the mouths of patients whose expectorations were known to contain tubercle bacilli, with the intention of catching any droplets of moisture that might be expelled during the act of involuntary coughing. The moist spots seen on the paper were then examined by Ehrlich's test. In two out of twelve pieces of paper thus examined, a few bacilli were found in four of the spots This method of examination was both laborious and unsatisfactory, and so Dr. Heron called to his assistance, his colleague, Dr. Ruffer, to examine by means of the culture method. The following is the result in Dr. Ruffer's own words.
"I have examined four cases of advanced phthisis to see whether the droplets of fluid, which are propelled by phthisical patients when coughing, contain the bacilli or not. The patients were made to cough on a piece of white paper, and the droplets of fluid present on the piece of paper, examined by pressing a clean cover-glass on them, and by isolation in cultures in glycerine-agar. The two first patients (a and b) coughed unconciously on the paper. In the first (a) one droplet out of several examined, showed the characteristic staining reaction of tubercle bacilli, but I was unable to isolate the latter by cultures. In the second case (b) I was able once to isolate the tubercle bacilli on glycerine-agar, out of a pearl-like drop coughed on the paper. I was not successful in four other attempts at isolation, but obtained positive results twice, with cover-glass preparations, though I was unsuccessful in several other attempts.
The third (c) and fourth (d) persons were cases of advanced phthisis also, but were instructed to cough on a piece of paper held about four inches from the mouth. I was unable to find tubercle bacilli after repeated examinations, and in d I only once found a few in five cover-glass preparations examined. Attempts to isolate the bacilli in c and d were quite unsuccessful."
In the 24th volume of the " Proceedings of the Royal Society," Dr. Ransome records a set of experiments he carried out He condensed the vapour of the breath, in a large glass globe surrounded by a freezing mixture. On examining the vapour of the breath obtained in this way, he found tubercle bacilli in the case of two patients suffering from phthisis; but failed to find the organism in several cases of acute phthisis, and also failed to find any in the aqueous vapour condensed from the waiting-room of the Consumptive Hospital in Manchester.
Dr. Theodore Williams performed a number of experiments, which he carried out in the extraction shaft of a hospital ward, filled with patients in an advanced stage of consumption. Glass plates, well cleansed, sterilized, and smeared with glycerine, were hung up in the extraction shaft for two or three days at a time. These plates were then examined, and a few well marked tubercle bacilli were found. These experiments, however, are open to one very serious objection, inasmuch as they do not indicate the source whence the bacilli arise-from the patient's surroundings, or from his breath..
This brings us to a second source of infection-namely, the sputum.
In marked cases of phthisis, it is a well-known fact that the expectorations teem with bacilli; and that these organisms retain their virulence, and are capable of producing true tuberculosis after dessication, and even after considerable time has elapsed since ejection from the host, has been now proved indisputably by experiment.
Dr. Cornet carried out observations at the Berlin Hygienic Institute extending over a couple of years. His experiments were devised to find out whether tubercle bacilli could be found in the surroundings of consumptive patients in such numbers, and sufficiently active to be a source of danger to animal life. lie used sterilized sponges, with which he washed walls, furniture, or any articles to be tested. A medium of broth was used for culture purposes, and was inoculated by the sponges. Guinea-pigs were then inoculated with the broth, with results that warranted the conclusion that tubercle bacilli are often found where consumptives live, and in sufficient numbers to endanger animal life. The guinea-pigs were killed after forty days. Of 21 hospital wards (where the majority were consumptives), r j produced tuberculosis in the guinea-pigs. Lunatic asylums were often found infected with bacilli, and rooms in private houses where consumptives had lived. In an hotel room where a tuberculous woman was living, bacilli were found in the bed stead and picture-frames. In the case of a young man who had been ill for nine months from consumption of the lungs and larynx, and whose habit it was to spit upon the floor, bacilli was found upon the walls. This man's room and person were kept scrupulously clean. Taking that for granted, the case shows, as Cornet points out, how, even where cleanliness is prevalent, the cause of tubercular disease may remain in the room, especially if the patient is not careful as to his spitting.
In the work-shops of a tailor and a corset-maker where, in the former case the master, and in the latter a workman, were ill of consumption, bacilli were found upon the walls of both. In the case of the corset-maker, the examination of the room was undertaken, because of the illness of a young rnan who had developed consumption while employed in the room with his consumptive fellow-workmen.
In the house of a woman who was consumptive, and on the walls of whose room, and on her watch-case, tubercle bacilli had been found during her life-time, these organisms were found in the same room when a second examination of it was made, six weeks after the woman's funeral had taken place.
Animals were inoculated with some of the bacilli then found, with the result that all became tubercular with remarkable rapidity.
Three hundred and ninety-two animals were inoculated with dust taken from the private dwellings of consumptives, from hospitals, streets, and other places, with the result that 59 of these animals became tuberculous, 196 of them were killed by the germs of other quickly fatal diseases, only in 137 cases were the inoculations not followed by any evidence of disease having been communicated to the animals operated upon.
Cornet records one very important fact brought to light by these experiments, and that is, that he never found bacilli in rooms where the patient used a spittoon.
He paid particular attention to these rooms and went to some trouble to satisfy himself thoroughly on the matter.
In the light of these experiments, one would naturally expect, that to meet cases which could reasonably be assumed to be due to contagion would be an every-day occurrence. Such, however, is by no means, the case. Burney Yeo, during ten years which he spent at an institution, devoted to the treatment of consumption, saw some 27,000 cases, a large percentage of which were actually suffering from phthisis. He considered that, if consumption be a contagious or infectious disease in the same sense as other recognised contagious diseases, then one ought to find conveyance between husband and wife to be frequent among the poor. In order to test this, he collected the particulars of 1,055 cases that came under his care. Of these, 621 were males and 434 were females.
Of the 621 males-
306 were married, 297 were single, 18 were widowers (37. of whole, 67, of married.)
Of these 18, only two could positively state they had lost their wives through consumption, and one of these had been dead 13 years. Six of them had lost near relations, (father, mother, brother, or sister) giving a presumption of heredity, and in 10, no precise information could be gained.
Of 434 females- 199 were married, 206 were single, 29 were widows (77. of whole, 15% of married). Of these 29 widows. 5 were able to state that their husbands had died of consumption; one lost her husband in a "fit ;" six had lost near relations by phthisis ; and 17 could give no precise information
At the same time cases were being investigated among the in-patients by the Resident Medical Officer.
Of 94 males in hospital- 53 were married, 62 were single, 9 were widowers. Two of these widowers lost their wives by phthisis, and of the 53 living, all were healthy except two,
Of 83 females- 15 were married, 62 were single, 6 were widows. Of the six widows, three had lost husbands by phthisis, although in two of these cases there was a strong presumption in favour of hereditary predisposition. The husbands living were all healthy.
Dr. Hermann Weber, in a paper read before the Clinical Society, gave details of 68 cases-39 husbands and 29 wives.
Only one of the husbands of the 29 wives became diseased, while the wives of 9 out of the 39 husbands died of phthisis. These nine husbands lost 18 wives as follows One lost four wives, one lost three, four lost two each, and three lost one each. One of Dr. Weber's cases is very remarkable. A young man who had lost mother, two brothers, and a sister through phthisis, and had himself suffered from hmmorrhage of the lungs, married at the age of 27, he then being in good health. His first wife was healthy, and came of a healthy stock. She died of consumption after her third confinement. His second wife, who was apparently healthy at marriage, died at the end of twelve months of galloping consumption. His third wife was a robust young woman of 25, belonging to an exceptionally healthy family. She developed symptoms of phthisis in her second pregnancy, which ran a rapid course, and ended fatally in about four months. His fourth wife was a perfectly healthy young woman of 23, with very good family history. Three months after her first confinement, she showed symptoms of phthisis, and died at the end of nine months, notwithstanding two sea voyages she undertook. After death she was found to have tubercles in the liver, spleen, and intestines, as well as in the lungs. The husband of these wives, who was a sailor, though apparently in good health, was found, on physical examination, to have morbid changes about the apex of the left lung. No doubt the life at sea kept his disease in abeyance, for when he came to be laid up, through an accident, the disease suddenly became active, and he died of consumption within two years. In Dr. Weber's second case, three wives of a consumptive husband died of consumption, which appeared in each case either during pregnancy or immediately after delivery. The other seven cases each presented this same feature, namely, the wives contracted the disease during pregnancy, or immediately after.
To sum up, out of 39 consumptive husbands, nine conveyed the disease to their wives, 18 in number; whilst out of 29 consumptive wives, only one conveyed the disease to her husband. It was also noticed that in the infected wives, the disease ran an unusually rapid course; whilst in the infected husband, it was more or less chronic, stationary, and apyretic. The fact that the onset of the disease occurred during pregnancy, and also that the wives suffered in an immensely greater proportion than the husbands, suggested the idea that infection occurred through impregnation, or by meals of the fætus rya ufero, just as in constitutional syphilis. But it is well-known that the puerperal state is particularly favourable to the reception and cultivation of the germs of many infectious diseases, and it may be fairly presumed that this peculiar vulnerability may extend to the tubercle bacillus.
When we take the evidence of the London Hospitals for Consumptives, where large numbers are congregated together, many of them in acute and advanced stages of the disease, we would naturally expect to find them perfect hot-beds of infection. Such is not the case however. The statistics of the Brompton Hospital, published by Dr. Cameron, in the " Lancet," of 1867; and by Dr. Williams and Dr. Edwards, in the "British Medical Journal," for Sept. 30th, 1882; and those of the Victoria Park Hospital, published by Dr. Andrews (Croonian Lectures, 1884), directly negative the idea of infection, either to the resident staff or to patients admitted into the wards for other diseases.
Musgrave Clay collected 111 cases of infection, for the most part due to close attendance on husbands and wives.
The Collective Investigation Committee of the British Medical Association, in reply to a circular on the subject, addressed to 12,000 members, received 778 negative replies, 39 doubtful, and 261 affirmative. Dr. Williams says :-" My own experience is that, for the last 20 years, I have carefully watched for cases of infection in hospital and private practice, and though I have often come across a certain number of apparent cases, they have never stood the test of close inquiry, there being always some additional element to explain the causation of the disease. Except a few cases of husband and wife infection, and a very few instances of sisters, or mothers and daughters, sleeping together, in an ill-ventilated bedroom, apparently contracting disease, I cannot recall any infectioe cases."
So far we have dealt solely with the entrance of bacilli by the respiratory tract, but there are still two other modes of access, namely, by the skin, and digestive tract. Access by means of the skin must be an exceedingly rare occurrence, but we have sufficient cases recorded to place its possibility beyond a doubt. A case recorded by the " London Medical Record," August, 1886, is that of a healthy servant girl, aged 24, who cut her hand with the fragments of a spittoon containing bacilli-laden sputum. A tuberculous nodule developed at the wound, and the axillary glands became affected.
In the "Annales de Dermatologie et de Syphiligraphie," vol. v., 1884, we have the case of a man, 70 years old, with neither personal nor hereditary tendency to tubercle, who developed a whitlow in his left thumb. The abscess was opened with a bistoury. Some time afterwards, ulceration set in just above the wrist on the radial side. Tubercle bacilli were found in the pus from this ulcer A year later this man developed phthisis in the left lung. He died, and the post-mortem examination revealed the presence of tubercle in the lungs. The writer argues that it is reasonable to suppose that the whitlow was either itself the result of tuberculous inoculation, or was opened by a knife which carried the infection. He assumes that the pulmonary tubercle was caused by infection from the site of the whitlow.
In Volume VI. of the same Annales, Dr. Tscherning, of Copenhagen, reports the case of a woman, 24 years of age, robust and of perfectly good family history, who was cook in the house of Professor H. The Professor died in 1884 of pulmonary consumption of six months' duration. During the last days of his illness, his expectoration was a pure cultivation of tubercle bacilli. A few days before his death his glass spittoon was broken, and this servant pricked her finger with a fragment. A fortnight later she consulted Dr. Tscherning for the first time. She then had symptoms of whitlow of the injured finger. Carbolic dressings relieved the symptoms. Eight days later there was no trace of suppuration, but a little hard lump about the size of a pea was felt under the skin. It was painful, and surrounded by oedema. About a month later the doctor cut out this nodule, and found it composed of granulation tissue. It lay between the skin and the tendon. Healing took place rapidly, and a month later still, the patient complained of a swelling that involved both the injured finger and the palm of the hand. This got worse for some six weeks, when a thickening in the sheath of the tendon could be easily felt through the cedematous skin. At the same time two swollen glands in the forearm and two more in the axilla were noticed. Otherwise the woman was in perfect health, and the lungs were sound. A week later Professor Studsgaard cut out the diseased glands and removed the finger. Under the microscope the diseased tissues were found studded with typical tubercles ; that is to say, tubercles with caseous centres and giant cells. In these giant cells and around the caseous material, and more frequently in isolated positions, tubercle bacilli were found. The patient was in good health two months after the operation. These exceptional cases, however, only show the rarity of the occurrence.
The disease may also gain entrance by way of the digestive tract. The milk of tuberculous cows is not only poor in quality, but may impart the tubercular disease to the drinkers. Klebs and Gerlach proved this in the case of guinea-pigs and rabbits. M. Pench described, before the French Academy, how he fed two rabbits on milk from a tuberculous cow. One died, and the other was killed soon after, and both showed tuberculous granulations. Boiling the milk evidently does not render it innocuous when the disease is far advanced, as is shown by Mr. Fleming, F. R. C. V. S. He took six pigs from the litter of a healthy sow, and fed four of them with the milk from a cow which, after death, showed tuberculosis of liver, peritoneum, ovaries, thoracic and abdominal glands, and pleura, with cheesy deposits in the lungs.
Two of these pigs he fed with uncooked milk; two he fed with cooked milk ; and the remaining two he kept as control animals.
After some months the two control animals were killed and found quite healthy ; the two fed on cooked milk were killed and showed severe generalised tuberculosis ; and of the two fed on uncooked milk, one died showing caseous enteritis, and the other was very unwell though still alive.
In the "Deutsches Archiv ffir Klinische Medicin," Vol. XLIV., Hirschberger publishes a paper which deals with the experimental evidence relating to the question of the infectiousness of the milk of tuberculous cows. He says that zti per cent. of all children dying under one year of age, are killed by tuberculosis ; and he thinks it but reasonable to connect the fact with tuberculosis in cows. Under the guidance of Professor Bollinger he carried out a series of experiments with the milk of tuberculous cows, with a view of throwing light on the matter. To obtain the necessary milk, the whole udder of a tuberculous cow, just slaughtered, was amputated. In other cases milk was taken in the ordinary way from tuberculous cows The milk was taken up in a perfectly sterilized syringe, and no tinge of blood was allowed to be present. This was then injected into
the abdominal cavities of young guinea-pigs. Every experiment was submitted to Bollinger himself. Not a single guinea-pig died of sepsis. Many of the animals were killed, and both Hirschberger and Bollinger satisfied themselves that tuberculosis had commenced with unmistakable distinctness in most of them. In the case of five highly tuberculous cows, inoculation with their milk gave four positive and one negative results. In the case of six moderately tuberculous cows, four positive and two negative results were obtained. In the case of nine cows which had tubercular diseases in the lungs only, three inoculations with their milk gave positive results, and six gave negative results.
It is evident, therefore, that milk, under any conditions, derived from cows no matter how slightly infected with tuberculosis, is totally unfit for human consumption.
Professor McFadyean, of Edinburgh, stated in his evidence, before the Committee appointed to inquire into pleuro-pneumonia and tuberculosis in the United Kingdom, that he had observed tubercle bacilli in cows milk and that he considered that fact, unsupported by other evidence, sufficient to prove that such milk may cause tubercular disease. He laid most stress, in his evidence before the Committee, upon certain cases which seemed, both to him and to Dr. Woodhead, strongly to suggest that tubercular disease may be carried by infected milk. They examined about a dozen cows which supplied milk to a public institution. Very decided evidence was found of tuberculosis in the udders of three of those cows. The deaths from phthisis in this institution have been 30 per cent. of all deaths, and in another year 40 per cent. A number of pigs were kept to use up the refuse milk. These pigs had been very unhealthy and, Dr. McFadyean was told, a number of them had died of ` lung disease.'
In his evidence before the same Committee, Dr. Robert Peel Ritchie, President of the Royal College of Physicians, Edinburgh, refers to the case of the institution mentioned by Professor McFadyean. He states that when the supply of milk in use in the institution was stopped " the health of the children and pigs improved-I.e., the disease ceased to attack the healthy children and pigs." Dr. Ritchie further stated that the great mortality in Edinburgh from tuberculosis during the last 1o years, amongst children under five years of age, had attracted much attention. It amounted to 6-8 per cent, of the deaths, that is to say, of 44,616 deaths at all ages, 3,054 occurred in those under five years of age from tuberculosis. He also pointed out, that according to the returns of the Registrar-General for Scotland during the 1o years ending 1885, 7,415 children under five years of age, died from tubercular disease of the abdominal glands, and 13,216 children within the same age limit, of tubercular meningitis. Dr. Ritchie makes the following statement with reference to these death-rates :-" Now, it occurs to myself that possibly the greater number of inflammations of the brain have been preceeded by disease of the glands of the abdomen. One point is this, that in the first three months of the lives of these children, tabes is in a larger proportion as a cause of death, but at all other periods up to five years of age tubercular meningitis kills the largest number. Tubercular meningitis, according to the return, may thus be regarded as due to infection from tubercular glands. The glands, therefore, possibly may have become affected from the milk which the children have been fed on-(I am merely speaking as a possibility)-and the secondary disease, inflammation of the brain, may have thereafter resulted."
It is only fair in this connection to remember that children brought up by hand are naturally not so healthy as those brought
up on the breast. The records of the Manchester Children's Hospital conclusively prove this. Of 150 children reared exclusively
on the breast, up to 9 months or longer,
62 per cent. were well developed,
23 per cent. were moderately developed, 14 per cent. were badly developed; while, of 5o children fed exclusively by hand,
10 per cent. were well developed,
26 per cent. were moderately developed, 64 per cent. were badly developed.
It is well known that milch cows are much more frequently the subjects of tuberculous disease than any other kind of stock. It was stated in evidence before the Committee that the percentage of animals affected with tuberculosis in Dublin was 4·9.
Ayrshire Dairy cattle are markedly prone to this evil, the evidence at the inquiry quoted, being that 25, 30, or even 50 per cent of this breed had been found suffering from tuberculosis in some form or other at various farms.
We need go no further into this matter, as enough has already been said to prove that there is trustworthy experimental evidence, and a considerable weight of medical opinion in favour of the view, that tubercular disease is conveyed from beast to man by the milk of consumptive cows. Moreover, Hirschberger's experiments show that tubercular disease can never be regarded as affecting only that part of the body where its evidence can be either seen, or otherwise detected by our trained senses. Unless we deny the truth of the evidence of his researches, we must accept it as proved that it is never safe to regard an animal affected by localised tuberculosis, whose flesh or milk may be used as food by man, as ought else than an animal suffering from a disease which may, at any moment, infect practically its whole structure.
We have also to consider the likelihood of infection from the eating of the flesh of tubercular animals. It is now generally understood that the eating of any part of a carcase that is obviously tubercular, is likly to cause that disease in the animal eating it. Professor Fleming, in his " Veterinary Medicine," records many interesting experiments in this connection. Rodents, dogs, pigs, calves, fowls, and various other animals have been fed upon tissue taken from tuberculous animals, man included. Juice pressed from tubercular flesh has been injected under the skin of healthy animals; saliva, milk, and mucus taken from consumptives have been swallowed by healthy animals. Of course, a number of these animals remain apparently healthy after going through the ordeal ; but the great majority either died from tuberculosis, or, when killed, showed marked evidence of the disease in the form of tubercular deposits, &c., in their internal organs. In certain of these experiments the meat was first cooked, and when such was the case the disease did not follow its use; but should parts be only partially cooked, or underdone, the potency for evil seemed to still lurk in it. It must, however, be admitted that, while experiments of the kind indicated above have proved the danger of using as food meat obviously tainted with tubercle, the same kind of experimental inquiry has often failed to show that there is danger in using for food flesh which, though in itself apparently healthy, was obtained from the carcasses of beasts that had suffered from tubercular diseases of seemingly very limited extent. This is one of the most important and one of the gravest points requiring to be considered in connection with the laws regulating the sale of meat ; but, as it relates more to State medicine than to the present paper, we will not discuss it.
Some years ago, the Baden-Baden authorities made a very suggestive contribution to the study of the question of the carriage of infection by means of the flesh of tubercular cattle. They published a map which took in some jz townships, and was, therefore, a fairly large and safe field on which to crystallize out general principles. Two facts are brought out very prominently by this map, the first being, that the prevalence or otherwise of tubercular disease in cattle was co-incident with the prevalence or otherwise of tubercular disease in man; and the second being, that where butchers, who deal in cheap meat are numerous, there tuberculosis is exceptionally prevalent among the people. It is well known that at the time this map was published-about 1880-a very considerable trade was carried on in the sale of carcasses of tubercular cattle for human food. That trade was largely in the hands of the butchers who sold cheap meat, and so we have a remarkable series of facts which point to the conclusion that the cheap tubercular meat and the unusual prevalence of tuberculosis amongst those who fed upon it, have to each other the relationship of cause and effect.
Dr. Dreschfeld has made experiments with the juice of the flesh of six cows, five in an early stage of tubercular disease, and one in an advanced stage, although the flesh was apparently healthy. The results from the five cows were entirely negative, as the animals injected remained perfectly healthy ; but the juice from the flesh of the sixth cow, produced a small crop of tubercles at the place of puncture into the abdominal cavity of two rabbits, after the lapse of from three to five weeks, and material from this tuber cular growth injected into another rabbit gave rise to still more decided tubercle. Further experiments have been carried out by Dr. Dreschfeld with results that still further corroborate the evidence elicited by the above experiments.
Behrend, Klein, Toussaint, Von Wesener, Fischer, Baumgarten, Bollinger, Martin, and others have investigated this subject, and although in certain details they may differ, they all agree in regarding both the milk and flesh of tuberculoss animals as unfit for human food.
1 Wichmann " Hannoverischen Magazin," 1780.
2 "De Causa et Sedibus Morborum Epist," 22-3.
3 "Del Contagio del Vajucle," 1770.
4 Evidences of the Communicability of Consumption. G. A. Heron, 1890.
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