It is needless to repeat the various symptoms of tuberculosis according
to its different seats and the degree of its extension in the animal
body. In cases in which the indications are slight, greater importance
may be given to them through the knowledge of the existence of more
advanced or decided cases in the same herd, or the necropsies of animals
taken from it. Yet in the average herd it is safely within bounds to say
that three fourths of the affected cattle will escape condemnation if we
employ objective symptoms alone. In one herd of seventy head, in which
the tuberculin test condemned twenty-four head (being 50 per cent. of
the mature animals), I left the examination after slaughter to the
veterinarian of the A. J. C. C. who was at the time skeptical as to the
value of the tuberculin test. He wrote me afterward of his surprise at
finding every one of the twenty-four condemned animals tuberculous, when
not one of them had shown symptoms by which he could recognize the
disease in life. This is no exceptional case, and may be advanced rather
as a typical example of the ordinary infected country herd.
_Microscopic_ detection of the bacillus in the expectoration may be
successful in the horse with pharyngeal or pulmonary tuberculosis, but
fails in those forms that affect the other internal organs. It is all
but useless for the expectoration of cattle and dogs. When there is
cutaneous tuberculosis or a tuberculous fistula this is much more
valuable, and it is especially useful in dogs and parrots.
The precipitate in the centrifuge will often show the bacilli that are
present in milk, but in very many cases of tuberculosis the bacilli are
not present in the milk.
The centrifuge used on the _urine_ may also succeed when kidneys,
bladder or prostate are affected, but the bacilli are rarely found in
the absence of disease of these organs. The smegma bacillus is a source
of fallacy.
The serous effusions in the affected _serosæ_ (pleura, peritoneum,
pericardium, synovial cavities) may also be centrifuged and the presence
of the bacilli revealed.
The _agglutination test_ of Arloing and Courmont though often giving
positive results, (95.5 per cent. in pulmonary tuberculosis, 50 per
cent. in surgical, Arloing and Courmont; 40 per cent., Knopf; 25 to 50
per cent., Lartigan); yet proved too unreliable, and frequently gave
positive results when tuberculosis was absent. The best medium for
cultures to be so used is 6 per cent. glycerine bouillon, and the age of
the tuberculosis culture 8 to 12 days. One part of fresh blood serum of
the suspected animal in a sterilized capillary tube is added to ten
parts of the bacillus culture, and the tube placed in an oblique
position. In 2 to 24 hours a fine sand-like material precipitates along
the sides of the tube, and the microscope shows the bacilli in clumps,
absolutely still without even Brownian movements. Gallemaerts found that
it proved very satisfactory with the serum of Guinea pigs after three
days from intraperitoneal inoculation, was less marked after
inoculations subcutem, and that in man the agglutination appeared in
influenza and pneumonia in the entire absence of tuberculosis. Such an
uncertain test cannot be utilized in veterinary sanitary work.
_Experimental inoculation_ with milk, expectoration, morbid discharges,
the scraping of nodules, etc., is much more searching, and will detect
more cases than the microscopic examination. But it fails entirely in
cases in which the milk of unquestionably tuberculous animals is free
from bacilli, or in which the local nodule or discharge tested is itself
free from tubercle. It is a test of the local lesion and not of the
entire animal system.
In choosing a subject for inoculation, the first consideration is that
it must come from a healthy stock and be itself free from tuberculosis.
Next, it must be of a species actively susceptible to the habitual
tuberculosis of the animal from which the inoculated matter is taken.
Thus for man, ox, dog and parrot, the Guinea pig is especially
appropriate, while for gallinaceæ and horses, the rabbit is to be
preferred. Inoculation is usually made into the peritoneal cavity.
As a period of two or three weeks is usually necessary to allow of an
extensive development of tuberculosis, the method must be too often
discarded on account of the delay in obtaining results.
_Tuberculin test._ Many stock owners still entertain an ignorant and
unwarranted dread of the tuberculin test. It is quite true that, when
recklessly used by ignorant or careless people it may be made a root of
evil, yet as employed by the intelligent and careful expert it is not
only perfectly safe, but it is the only known means of ascertaining
approximately the actual number affected in a given herd. In most
infected herds, living under what are in other respects, good hygienic
conditions, ⅔ or ¾ are not to be detected without its aid, so that in
clearing a herd from tuberculosis and placing both herd and products
above suspicion the test becomes essential.
_Tuberculin_ is the bouillon in which the tubercle bacillus has been
grown, charged with the toxic products of its growth, but which has been
raised to a boiling temperature to destroy all germ life, and from which
the dead germs have been removed by passing it through a porcelain
filter. When a physiological dose of this has been injected, subcutem,
into the suspected animal, it has no effect on the non-tuberculous,
while in the tuberculous it produces, in the course of the next 24 hours
(usually from the 8th to the 16th), a steady rise of temperature by 2°
F. or more, followed by a slow subsidence to the normal. This may last
for from three to ten hours in different cases.
Among the precautions may be named:
1. The temperature of the animal is best taken at intervals, or at
least, morning, noon and night, on the day preceding the injection to
see that the animal shows no habitual rise at any time of the day. Yet
in busy field work the one night temperature taken just before injecting
will rarely fail to give a satisfactory normal as a standard for the
animal. Any quotidian rise almost invariably reaches its climax at
night.
2. _The subject must be in good general health._ If there is present in
the system any concurrent disease it may undergo an aggravation within
twenty-four hours and give a rise of temperature that will be mistakenly
set down for tuberculosis. At the very start, therefore, it is important
that the general health of the subject should be first assured by a
critical professional examination. If some other disease is present the
tuberculin test had best, as a rule, be delayed until that has subsided,
while if tuberculosis is found the test will be superfluous.
3. _The subject must not be within three weeks of parturition, nor about
to abort._ In many cases, though not in all, as preparations are made
for calving, the system becomes unduly susceptible to the presence of
tuberculin and that agent will cause a rise of temperature, though no
tuberculosis is present. Unless this source of error is carefully
guarded against the most valuable cows in the herd may be condemned
unjustly.
4. _The cow must not be within three days of the period at which “heat”
would naturally occur._ Under the excitement of œstrum the body
temperature usually rises two or three degrees, and if tuberculin has
been used this rise may be attributed to tuberculosis and a sound animal
may be condemned. Nor is it always enough that the animal is supposed to
be pregnant. Abortions sometimes take place unexpectedly and unknown to
the owner. If, therefore, a cow under the test and which is not well
advanced in pregnancy should show a rise of temperature it should be at
once ascertained whether the animal is not in “heat.” If symptoms of
“heat” are found she should be set aside along with any calving cows to
be tested again when such a source of error is no longer present.
5. _The tested animal must not be exposed to a hot sun in a closed
area._ In excess this will cause heat apoplexy, and the fever heat which
ushers this in, may easily be mistaken for the indications of
tuberculosis.
6. _Cattle taken from pastures must not be enclosed in a hot, stuffy
stable._ While they must be tied up to allow of the temperature being
taken at short intervals, coolness and ventilation should be secured in
summer by a sufficient air space and the requisite ventilating openings.
7. _Exposure to cold draughts between open doors and windows, or to wet
or chilly blasts out of doors should be carefully guarded against._ A
chill proceeding from any source and alike in the presence or absence of
tuberculin causes a rise of the internal body temperature.
8. _Heavy cows unaccustomed to stand on hard boards may have a rise of
temperature in connection with resulting tenderness of the feet._ One
must avoid hard floors on the day of the test or make examination of
feet and allow for attendant fever.
9. _Omission of the previous milking or a change of milker and
consequent retention of part of the milk_ will raise the temperature of
a nervous cow, and in careless hands secure an erroneous condemnation.
10. _Privation of water at the regular time will often cause rise of
temperature_ especially when on the dry feeding of winter. I have seen a
general rise of two degrees and upward from the delay of watering for a
single hour, while after watering the temperature went down to the
normal and remained so. Water always tends to a temporary lowering of
temperature but in the presence of tuberculosis it soon rises again.
11. _Change of food is liable to produce a slight indigestion and rise
of temperature._ This should be avoided as far as possible, and when a
herd is taken up from pasture for the test, it should have grass,
ensilage or other succulent food.
12. Cattle just from a long journey by road or rail, or other cause of
violent exertion are liable to have an elevated temperature from the
leucomain poisoning. Such should be left at rest until the transient
fever shall have subsided.
13. Violent handling of nervous cows in taking the temperature must be
carefully avoided. The operator who cannot handle them gently is not fit
for this work.
14. There must be evidence that the animals have not been repeatedly
tested at short intervals shortly before. In a number of instances I
have found a proportion of the cattle irresponsive to tuberculin, though
a _post mortem_ proved the presence of tuberculosis. Unscrupulous men,
wishing to sell on a guarantee, can avail of this in animals so
unaffected by the test.
15. The operator must have absolute control, even of the feeding and
watering of the animals on the day of testing. Otherwise the rise of
temperature may be prevented by a liberal use of antipyretics and a
false guarantee may be secured.
16. An unthrifty animal, having general symptoms suggesting
tuberculosis, must be subjected to the most critical examination in
addition to the tuberculin which in such animals often fails to cause
hyperthermia. Fortunately in such animals the tubercles are usually
numerous and extensive enough to be discovered through objective
symptoms.
17. Animals excluded from the test by reason of some individual
unfitness at the time (parturition, œstrum, abortion or any other
disease) must be marked and held for the test later after such
disqualification shall have passed.
18. The operator must bear in mind the possibility of transferring other
diseases from animal to animal, by contact, by the use of the same
hypodermic needle on two in succession, and above all by the clinical
thermometer. Diseases like contagious abortion, which present no obvious
symptoms in the intervals, are especially liable to be carried in this
way, and instances of the active extension of this after a test, have
come under my notice. The operator should always enquire carefully as to
the existence of abortions and sterility in the herd, put the aborting
animals by themselves, using a special thermometer upon them, and
carefully washing the hands before going to other cattle. It is well
further to clean the thermometer after each animal and disinfect it with
carbolic acid solution (5:100).
_Dose of Tuberculin._ Of the usual American preparation 2cc. (30 drops)
is adapted to a cow or ox of 1,000 to 1,200 pounds. For larger and
smaller animals a moderate encrease or reduction must be made, yet a
considerable latitude is allowable. The new-born calf will take five
drops and the animal of 700 pounds 25 drops.
_Technique of the Operation._ Lapses are so easily made when dealing
with a large herd and are so dangerous that a regular plan should be
systematically followed. The following will be found simple and
convenient:
1. Inject the herd at 10 or 11 P. M. to secure a good rest and be fresh
for the rise of temperature early next morning.
2. Before injecting have the subjects arranged in order and record them
by name or other means of identification, with age, sex, breed, weight,
pregnant or not, past or prospective date of calving, abortion,
indications of disease, temperature taken just before injection and
appropriate dose.
3. Inject into the loose connective tissue on the side of the neck, the
animal being held by the nose, if necessary, by an assistant.
4. Use a syringe which has not been employed for any infectious
products, and see that it is thoroughly cleansed and disinfected by
boiling or by filling it with a carbolic acid solution (5:100).
5. After drawing the appropriate dose into the syringe, wipe the nozzle
and dip it in strong carbolic acid before inserting it into the skin.
This safely disinfects any virulent matter that may be lodged on the
surface of the skin, and obviates those infected swellings and abscesses
that have been a cause of complaint by stock owners.
6. When the nozzle is withdrawn from the skin, wipe it and dip it again
into the strong carbolic acid to prevent any risk of infecting the
tuberculin into which it is to be plunged.
7. The nozzle is much more easily inserted in the skin if the latter is
pinched up so that the needle will transfix it at a right angle, instead
of passing through a greater amount of the dense tissue because of the
oblique direction. An excited animal with a thick, tense hide and a
contracted panniculus muscle will offer serious obstruction which
lessens greatly as the subject gets over its excitement and the muscle
relaxes.
8. Temperature should be taken at 6 or 7 A. M., eight hours after
injection of tuberculin, and every two hours thereafter, until the
sixteenth hour.
9. If any subject shows no rise of temperature until the 16th hour after
injection, its examination may be discontinued, but if it shows a slight
rise toward the 16th hour it should be continued until it has shown a
distinct reaction with steady rise and fall, or until, without such
distinct reaction, the temperature descends to the normal.
10. If one has shown a distinct reaction but is still rising at the 16th
hour, it should be continued till it begins to fall. The typical
reaction is one in which the rise and fall are both gradual, and extend
over a number of hours.
11. In recording the temperatures, there should be noted the exact time
of each feeding, watering and milking, or any other condition (change of
weather), which may in any way affect the heat production or radiation.
12. In old, emaciated animals and in second or third tests, Pearson uses
twice the usual dose of tuberculin or more.
_Tuberculosis Reaction._ With slight variations different operators make
their estimate of tuberculosis reaction on nearly the same general
basis. A rise of 2° F. over the highest temperature of the day or days
before, in the absence of any other appreciable cause, and provided that
the elevation has followed the tuberculosis type of gradual rise and
fall, is held to condemn. If, however, this rise does not exceed the
normal average, if the temperature before injection did not exceed 100°
and that after injection 102°, the case may well be held in doubt and
reserved for re-testing. If, on the contrary, the initial temperature of
the animal was 103°, and there was, between the 8th and 16th hours, a
gradual typical rise and fall, reaching 104° or a little over, in the
absence of any other cause for this, the subject would be condemned.
Cattle having an initial temperature of 103° or above are not favorable
subjects for the test, except in the case of calves in which the
temperature is normally higher and the reaction must reach a higher
point. In all cases of doubt it is well to hold for a second test,
unless urgent sanitary considerations demand that a herd should be freed
from the infection in short order. Then it may be better to risk a
single error, with the concurrence of the owner, than to leave a
possible centre of infection in the herd.
Local swelling in the seat of injection may be charged to lack of
antiseptic care, or the presence of septic germs in the system of the
animal prior to injection.
A chill during the period of reaction is not uncommon, especially in
cold weather, or in a draught of cold air. The coat may stare along the
spine in patches, or generally, tremors may be seen on the body or
limbs, and a clammy coldness invades the ears and horns, and especially
the points of the hocks and ischia. The back is sometimes arched and the
feet drawn together somewhat.
In the absence of any source of excitement the head may be less
elevated, the ears lopped forward or drawn back, and even the eyelids
may droop somewhat. These phenomena may last for a few minutes or for an
hour or two.
In testing other genera consideration must be had of the different
normal temperature (horse 99.5°, dog 98.5°, sheep or pig 103°, bird
106°), and the varying susceptibility to tuberculin, the Guinea pig
requiring a maximum dose relatively to its size and man or horse a
minimum.
_Effect of Tuberculin Test on the Later Average Health of the Animal
Reacting._ The transient fever and reaction on the day after injection
modifies the milk secretion temporarily to a certain extent in ratio
with the hyperthermia. The consensus of veterinarians of the largest
experience, and the voice of the International Veterinary Congress at
Berne in 1895, oppose the doctrine of any continuous effect on the
health even of the tuberculous. Yet in the case of Governor Morton’s
large herd of Guernseys a careful record of temperatures showed that for
weeks after the test the reacting animals presented oscillations which
were not shown before, and which were not found to occur in the sound
animals. In the activities of sanitary work such indications are easily
missed.
_Effect of Tuberculin Test on Sound Animals._ In 1894 I tested this on a
number of thoroughbred Jersey and grade cows, injecting them six times
at intervals of from five to fourteen days. It led to no appreciable
change of the general health as shown by the temperature, breathing,
pulse, yield of milk or its quality. Careful analysis was made of the
milk at each milking, and in two animals soundness was attested by _post
mortem_ examination. Similar tests made by the Bureau of Animal Industry
and others led to the same results. Cows in which the yield of milk was
on the gain continued to encrease in the same ratio as those that had
not been injected, and those in which it was on the wane showed no more
rapid decrease. The butter fats and total solids showed no variation
more than appeared in the healthy.
_Action of Tuberculin on Parturient Cows._ The testimony of Bang, Eber
and Pearson, based on a very extensive experience, would indicate that
the tuberculin test is not forbidden by the parturient condition. Eber
concludes that unless the initial temperature materially exceeds 39.5°
C. (103° F.) the parturient state is no barrier to successful testing.
My own experience, on the contrary, is that a considerable proportion of
parturient cows give a reaction when the initial temperature did not
exceed 103° F., and when no sign of tuberculosis could be found. As an
example, a cow in high condition, with an initial temperature of 102.8°
F., rose gradually from the eleventh hour after injection and reached
106.3° by the eighteenth, a rise of 3.5°. From the record she was not
due to calve for three months, but a fortnight later, when already
killed and laid open, she showed all the signs of parturition, a fully
matured calf, and not a trace of tubercle. This is far from unusual, and
I am convinced that many errors will be avoided by refusing to condemn
parturient animals or those within a couple of weeks before or after
parturition on the tuberculin test alone.
_Reliability of the Tuberculin Test._ Even in the most careful hands the
tuberculin test cannot be held to be infallible. A certain very small
proportion of cows react without the recognition of any tubercle post
mortem, some because of other bodily conditions, like parturition or
abortion, but in skilled hands these may be ignored in ordinary sanitary
work. Pearson claims to have had but 8 such cases in 4400 cows that gave
a typical reaction. He suspects that some of these even had undiscovered
tubercle, and Nocard thinks that all such cases are to be explained in
this way. On the other hand a very few really tuberculous animals fail
to react, some in connection with advanced disease, some because of
repeated previous testing, and some because of the introduction of
antipyretic agents into the system, but such cases can either be
detected and controlled or are so infinitesimal in numbers, that they
can be safely ignored in sanitary work. In skilled hands, the tuberculin
test will show at least ⁹⁄₁₀ths of all cases of tuberculosis, when other
methods of diagnosis will not detect ⅒th. See above case of herd where
objective symptoms showed nothing, yet tuberculin condemned half the
mature cattle, and post mortem confirmed this, the skeptical
veterinarian being judge.
_The Relation of the Bacillus Tuberculosis of Man to that of Cattle._ On
the discovery of the bacillus tuberculosis it was largely assumed that
it was the same in all tuberculous animals, in all organs and in all
circumstances. But it was soon found that the bacillus of chicken
tuberculosis differed materially from that of the mammalian, that it
could be inoculated only with difficulty on cattle or Guinea pig, as
could that of the latter on the bird. The bacillus of the chicken found
a most receptive home in the rabbit and horse, and was more easily
started in artificial culture in glycerine bouillon, than was that of
man or ox. But presently it appeared that the affinities and disparities
did not end here. The bacillus from man or ox led to much more
pronounced lesions in Guinea pigs than in rabbits, and the abdominal
bacillus of the horse was inoculable on the chicken. Both horse and
parrot proved receptive to the bacillus from man. Swine, like Guinea
pigs showed a receptiveness to the bacillus of man or ox. The bacilli
from the sputum, open tuberculous sore, or bones of man showed less
virulence for Guinea pigs and rabbits than did those from tubercles in
the human lungs and liver. The bacillus from the ox showed a greater
virulence toward rodents and other small animals than did the bacillus
from man. The bacillus of human sputum inoculated on the ox did not
habitually cause generalized tuberculosis, but oftentimes a local
tubercle or group of tubercles, and sometimes the inoculation wound
healed without permanent lesion. These last points were seized upon to
sustain a doctrine of probable duality for the microbe of tuberculosis,
but if duality it was quite evident it could not end there, but must be
extended to multiplicity, each small group of genera having a tubercle
bacillus peculiar to itself. Those who thought their interest lay in
arresting all sanitary control of tuberculous cattle and their products,
became urgent in opposition to active government measures, demanding
mathematical proof of the infection of man from cattle, under conditions
that would exclude the remotest possibility of the introduction of
infection from another source. The clearest and most abundant
circumstantial evidence would not suffice, they must have direct
experimental inoculation under conditions of precaution against outside
germs, which were practically impossible in any community, conveniently
ignoring that such inoculation, if successful, would have amounted to
manslaughter, and that no such experimental evidence has been had, or
can be had, of any of the deadly diseases of man. Infection by exposure
and accidental inoculations can be had in abundance, just as they can in
tuberculosis, but never under the rigid precautions which would exclude
the possibility of extraneous infection.
The subject has assumed such importance that I may be excused for
introducing a portion of my paper read before the New York State Medical
Society in 1900.
1. _This Variability is Common to Microbes Generally._ Certain bacilli,
like those of anthrax, grow in the living body as rods only, but become
long filaments in given artificial media. They produce no spores in the
living tissue, but do so readily in the carcass or soil. Transferred
from ox to ox they are generally fatal, but if grown for several
generations in Guinea pigs, and then transferred to cattle, the
resulting disease is slight (Burdon-Sanderson, Duguid, Greenfield).
Rabies passed from dog to dog is almost constantly fatal, but if passed
through the ape and then back to the dog it is comparatively harmless
(Pasteur). In both these cases the inoculated animals become immune from
the more virulent germs, showing that they have passed through the
actual disease in an unusually mild form. The later system of Pasteur is
founded on this same general truth, as are also the methods of lessening
the pathogenesis of germs by subjecting them to compressed oxygen, to
graduated heating, to an altered chemical condition of the culture
medium, to antisepsis, etc. For a time such weakened cultures often
retain their lessened pathogenesis, even through a succession of
cultures in a susceptible animal body, acting as if the germ were indeed
a distinct species. But it might well have been considered that a
microbe which had changed its aptitudes in a given environment could
presumably revert to its original habits under the incentive of a
suitable medium. And this is precisely what does take place. Pasteur has
shown that the less potent rabic virus becomes more potent when passed
several times through the body of a rabbit, and that the weakened
anthrax germ acquires greater force when passed through a series of
small birds or newly-born mammals.
To come to tuberculosis, Trudeau tells us that a culture of bacillus
tuberculosis from man inoculated on the rabbit, and then cultivated for
two years _in vitro_, becomes much less destructive to Guinea pigs, and
that after six years of such artificial culture all the Guinea pigs
inoculated with it live for many months, some for two and a half years,
and some even recover. The usual life of the Guinea-pig after
inoculation is seventeen days.[3] All of our zymotic diseases have in a
similar way cycles of malignancy and benignancy. For a series of years
measles, scarlatina, diphtheria, smallpox, or grippe have an unwonted
mildness, and, again, one or another merges into a cycle of extreme and
fatal malignancy. Rinderpest on the steppes of Asia is comparatively
harmless to the native stock, but among outside cattle imported into the
steppes or attacked in their native lands it is habitually fatal. Texas
fever is mild among the indigenous cattle in the Gulf States, but very
deadly to Northern stock. Glanders is not at all fatal to horses of the
plains, the Rockies, or the Sierras; but it becomes redoubtable when
these horses carry it to the Eastern seaboard, and still more so in
Western Europe. It is a common experience to see a malady transformed
through the effects of heredity or acquired immunity, through
environment or the temporary mitigation of virulence in the germ; and
again we see the same disease, no longer restrained by such inhibitory
conditions, bursting forth as a malignant and deadly plague. We have,
therefore, no warrant for the hypothesis that a pathogenic germ which,
under given conditions of life, has lost in pathogenesis, but not in
vitality, should continue forever to exist as a harmless microbe.
Footnote 3:
Johns Hopkins Hospital Reports, Bulletin 100.
2. _Varying Malignancy of the Tubercle Bacillus in Man._ Nothing is more
familiar to physicians than the slow progress of tuberculosis of the
lymph-glands and bones, on the one hand, and its frequent rapid progress
in pulmonary, abdominal, or encephalic organs on the other. It has on
this account been rather difficult to persuade many of the etiological
identity of scrofula and consumption. In experimental tuberculosis the
same truth constantly crops up. Arloing and his followers found that the
tubercle bacillus from the lymph-glands of man proved less virulent and
deadly than that from the human lungs (_Lecons sur la Tuberculose_). As
early as 1880, Creighton drew attention to this in his work on _Bovine
Tuberculosis in Man_.
But the bacillus from the lungs is subject to variations of this kind.
Among seven specimens of human sputum, cultivated by Theobald Smith, six
had a fair average vitality, while the seventh failed to perpetuate
itself on dog serum.[4]
Footnote 4:
Journal of Experimental Medicine, 1898, No. 111.
It should be strongly emphasized in this connection that the failure of
extension and generalization of the sputum germ when transferred to
cattle does not distinguish it from the tubercle bacillus as conveyed
from ox to ox. Everyone at all experienced with the tuberculin test well
knows that in most herds the majority of the tuberculous animals show no
generalization, but only a localized tuberculosis. There is reason to
believe that even recoveries take place after slight infection, and it
is certain that many tuberculous cattle continue for years in what
appears to be good general health. Unless in particularly susceptible
subjects or under specially poor hygienic conditions, or unless in case
of reinfection, the average bacillus of bovine origin habitually fails
to produce in other cattle a rapid extension and generalization.
3. _Interchangeability of Bacillus of Man and Bird._ Of all known forms
of tubercle bacillus that of birds is the most distant from that of man
or ox, and yet the beautiful experiments of Nocard[5] serve to establish
their essential identity. Taking the bacillus of human sputum, which
would not infect the fowl, he enclosed it in collodion capsules, which
confined the bacilli while allowing transudation of the animal fluids,
and left these in the abdomen of the chicken for not less than four
months. He repeated this three times in succession with the product of
the original sputum germ, and obtained a bacillus which was actively
pathogenic for the chicken, though it had been harmless after the
sojourn of four and eight months respectively.
Footnote 5:
Annales de l’Institut Pasteur, September, 1898.
This may explain the reported cases in which a flock of poultry have
developed tuberculosis a few months after they were placed in the hands
of a consumptive caretaker. That such transmission does not always occur
is not surprising, considering that transmission between man and man is
infrequent in comparison with the number of exposures. So in cattle the
majority of exposed animals usually escape, although in such a case
there can be no plausible explanation on the ground of a difference of
germ. We have in every case to consider the necessity for receptivity as
well as infectivity, and the lack of either is a bar to infection. When,
however, we assume that the most diverse tubercle bacilli are
descendent’s of one original stock, that a large herd must furnish some
animals of more than usual susceptibility, and that such animals are
subjected to continuous accessions of both bacilli and toxins, we can
easily understand how some of the more adaptable germs will in time
accommodate themselves to the new medium. A Pettinkoffer, with an immune
constitution or a specially vigorous gastric digestion, may with
impunity drink a culture of cholera spirillum, but the same is not true
of the drunkard fresh from a spree and with seriously impaired
digestion.
_Bacillus Tuberculosis in Man and Ox. Points of Similarity._ The
bacillus tuberculosis of cattle is in general shorter and thicker than
those of man, but many in both subjects are morphologically
indistinguishable. Such differences are often far exceeded by different
specimens of one stock of germ seeded on different media. There is no
great difference in the thermal death point, and the viability in light,
dryness, cold and putrefaction. The tendency is in all cases to colonize
the lymph plexus or glands and to develop the specific lesions, with
slight variation in detail. The slow development of the lesions from
both forms of bacilli and their histological similarity is another
argument for their essential identity. The slow growth of both on
artificial media, the demand of each for a medium having the same
approximate composition, and the similar pathogenic and diagnostic
characters of the toxic matters elaborated by both germs bespeak a
primary identity. The very remarkable staining qualities of tubercle
bacillus, from whatever source it may be drawn, are no less remarkable.
_Tuberculosis of Man and Ox Coextensive._ The prevalence of tuberculosis
in man and ox in the same country and district is so frequent that it
may be safely set down as the rule. Among ichthyophagists and great
fishing communities, like the people of the Hebrides, Iceland,
Newfoundland, Greenland, and the coasts of Hudson Bay, tuberculosis is
rare. In these countries cattle are few or absent, or, like the hardy
highland kyloes of the Hebrides, they are kept in the open air. The
immunity of the people is not due to insusceptibility, since they fall
ready victims to tuberculosis when removed to infected countries and
cities.
In Northern Sweden, Norway, Lapland and Finland, where cattle are scarce
and reindeer plentiful, tuberculosis is said to be rare, though the
inhabitants live in the closest of dwellings through the long winter. In
most of the Pacific islands there are no cattle, and the natives are
comparatively free from consumption. In Hawaii, since the introduction
of cattle, consumption has increased. Australia and Tasmania, which
forty years ago were the great resorts for English consumptives, have
become increasingly the homes of infection since the development of the
cattle industry and the influx of phthisical subjects. Minnesota and
Dakota, in the early days, were held to be incompatible with
tuberculosis, but since the advent of the white man and his stabled
herds they have largely lost their sanitary reputation. The highest
known mortality from tuberculosis to-day is that of the reservation
Indians of these States, who feed on raw, diseased beef. In the Kighiz
steppes the Tartars subsist on the flesh and milk of their solipeds, and
largely escape consumption. In Japan, Dr. Ashmead tells us that the
common people escape tuberculosis, while the aristocracy suffer
severely. He attributes this mainly to the debauchery of the ruling
class; but it must not be overlooked that they eat freely of beef and
dairy products, which the rice-eating poorer population do not. The same
remarks apply in measure to the mandarin and plebian classes in China.
Holden tells us that tuberculosis is rare in Columbia, Ecuador and on
the eastern slopes of the Andes, where little or no milk or butter is
used. It must be further borne in mind that in these countries all herds
live in the open air, and practically escape infection.
These examples must be contrasted with the consumers of beef and milk in
civilized temperate countries, where the stock are largely kept indoors.
A general average mortality of 7 or 8 per cent. from tuberculosis, and
the _post mortem_ evidence in European and American hospitals of 33 to
50 per cent. which show tubercular lesions, recent or remote, cannot be
lightly passed over. The contrast with our reservation Indians is still
more striking. Holden and Treon testify that the meat furnished to the
Indians is always poor and often diseased, and that when the stock
arrives our hungry wards devour the internal organs raw, or, later, the
flesh as pounded preserved meat, and still uncooked. The deaths of these
Indians from tuberculosis is 50 per cent. of the total mortality.[6] Dr.
Washington Matthews, who spent twenty-one years among the Indians, gives
their food as the main cause of the disease, and states that when the
supply of fresh meat is liberal the death rate from tuberculosis is
highest (Census of 1880).
Footnote 6:
Medical Record, August 13, 1883.
If we now contrast this fearful mortality with the immunity of the
Indians of Hudson Bay, Great Slave Lake, Alaska, and the North
generally, we have a most suggestive picture. It may be conceded that
the extreme Northern Indians, being beyond the cereal region, have a
slight measure of protection in their meat diet; but the recent spread
of tuberculosis, like a plague, among the inhabitants of Barrow Straits,
when introduced by the frozen-in whalers and the relief party, is
sufficient disproof of any claim of special insusceptibility. There can
be no doubt that in this, as in other virulent diseases, the rule holds
that the long absence of the infection secures the preservation of the
susceptible lines of blood, so that when the contagion does come it
finds a more inviting field than in countries in which the more
susceptible strains have been killed off and the comparatively immune
have survived. Toward the Arctic circle the Indian must crowd into
closer quarters in winter than his brother further south; but, in spite
of all, the beef-eating Indian is being rapidly exterminated by
tuberculosis, to which his brother of the north is a comparative
stranger.
_Exceptions: Their Explanation._ This statement would be incomplete
without a notice of exceptions to the rule. The Cape Town branch of the
British Medical Association reports “that tuberculosis is rapidly
increasing there in the human population, while tubercle in cattle is
almost nonexistent.” This finds an abundant explanation in the different
conditions of life. The men live indoors and concentrate the infection,
whereas the cattle enjoy an outdoor life and escape. In a latitude of
30° south, where frost is rare, and with a dry climate (12 to 30 inches
of rain per annum), the colonists find no occasion for housing their
cattle, so that the conditions for the prevention of tuberculosis are
ideal. It may be added that cattle are far less numerous in Cape Colony
than they formerly were. The destruction first by lung plague and later
by rinderpest has made the cattle industry extremely hazardous, and even
before the advent of the rinderpest many had abandoned cattle and taken
to sheep.
Parallel cases can be found in other countries. In Egypt, the great
resort of consumptives, cattle are almost immune, the abattoirs
furnishing about one tuberculous ox in ten thousand killed.[7] From
Tunis (Alix), Algiers (Sarciron, Plaise), and Senegambia (Lenoir) a
similar testimony comes. Cattle imported from Europe may die of
tuberculosis, which is liable to assume a rapidly fatal type; but the
native cattle, kept in the open air, are practically exempt.
Footnote 7:
Danzon. Études Expérimentale et Cliniques sur la Tuberculose, vol. i.
p. 350.
Jersey cattle in their native island, staked out at pasture all the year
round, show little or no tuberculosis, whereas the housed Jerseys of
England and America suffer severely. The cattle of our Gulf Coast
States, kept on ranches in the open air, are largely immune, and the
cattle of Columbia, Ecuador, Peru, and the Argentine Republic largely
escape; but the housed dairy cows of our Southern cities show a very
high ratio of consumptives. Consumption becomes more and more deadly in
the Southern negro even in the country localities, while the outdoor
cattle of the same districts escape.
The absence of tuberculosis from the sanitarium herd at Saranac requires
to be explained on a different basis. This herd is housed in winter, and
infection, once introduced, would have opportunity to spread. The
absence of tuberculosis is highly complimentary to the management of the
establishment. But a similar immunity is the rule for all well-managed
sanitariums, and not as regards cattle only, but man as well. At Argeles
no case of tuberculosis contagion to attendants occurred in ten years
(Ferrand). At Soden baths, in a village of 1500, there were in
thirty-four years 65 deaths, 15 from consumption (Hopt). At Falkenstein,
in fifteen years, one attendant became tuberculous (Jousset). At
Görbersdorf the cases of consumption in the village and environs
decreased (Knopf). At Brompton, London, in thirty-six years, among 150
attendants, but one became consumptive, though they individually served
for from fifteen to twenty-four years, and nearly 40,000 patients had
been received.[8] A well-conducted sanitarium is and should be a safer
place than the average community, in which 15 per cent. and upward are
tuberculous. The educational influence of such an institution should
decrease tuberculosis in the surrounding districts.
Footnote 8:
Études Expérimentale et Cliniques sur la Tuberculose, vol. iii. p.
408.
_Cases of Direct Infection from Man to Ox._ Chauveau induced
tuberculosis in cattle by feeding the tubercle from the lungs of man.[9]
Footnote 9:
Arloing. Tuberculosis Congress of 1891.
Nocard relates that a Beauce farmer, with a finely appointed stable and
healthy herd, in 1883 employed a dairyman who had cough, profuse
expectoration, and occasional hæmoptysis, and who had been several times
in the hospital in consequence. He slept in the cow stable directly over
the cows. In 1886 two cows, stalled immediately beneath him, showed ill
health and were put up to fatten, but did badly and showed extensive
tuberculosis when butchered. The dairyman stayed until 1891, having to
go to the hospital several times in the interval. In 1892 the tuberculin
test was applied and seven more cows were found to be tuberculous.
Huon tells of a cow bought to furnish milk for calves used to raise
vaccine. She stood the tuberculin test, and was carefully secluded from
all other cattle, but soon began to fall off, and in six months was very
much emaciated, responded to the tuberculin test, and when killed showed
extensive tuberculosis. Her caretaker at the vaccine establishment had
what was believed to be chronic bronchitis, but when he died, soon
after, this was found to be extensive pulmonary tuberculosis.
Bollinger inoculated a three-months’ calf with liquid from human
tubercle and killed it seven months later. Fibroid pedunculated tumors,
from a pea to a walnut in size, hung from the mesentery and spleen, and
the mesenteric and retroperitoneal glands were tubercular.[10]
Footnote 10:
Münchener medicinische Wochenschrift, 1894.
Sidney Martin furnishes the following: Four calves were fed 70 c.c. of
sputum containing a large number of bacilli. Three were killed after
four, eight, and twelve months respectively, and had severally 53, 63
and 13 nodules on the small intestine, mostly on Peyers’ patches. Two
calves received at one dose 440 c.c. of tuberculous sputum, and were
severally killed after eight and nineteen weeks. The first had
tubercular nodules in the intestine and mesenteric glands.[11]
Footnote 11:
Report of Royal Commission of 1895.
Frothingham injected into the peritoneum of two calves, three and
thirteen weeks old, a culture of tubercle bacilli isolated one year
before from the liver of a child. Slight local nodules were produced,
some like spontaneous tubercle, others granulation tissue.
Theobald Smith inoculated sputum into the chest and abdomen of the
following:
1. A yearling heifer, which was killed two months later and showed on
the pleura near the seat of infection a mass of tubercles, one by one
and a half inch in diameter, with partly caseated centres; also a nodule
one-eighth of an inch on the right lung, and small tubercles attached to
the diaphragm and omentum.
2. A yearling injected in the same way showed in two months on the
diaphragm a mass of tubercles two inches in diameter, and a second mass
one inch in diameter on the ribs near the seat of infection.
Microscopical examination failed to detect bacilli, but there is no
evidence that they were sought by culture or inoculation.
3. A cow injected in the chest and killed after two months showed
tubercles of the lungs, pleura, and mediastinal glands, partly caseated
and containing bacilli. Vascular fringes hung from the pleura.
4. A cow receiving a chest injection of sputum culture and killed in two
months showed fringes and pendulous masses on the pleura, with small
tubercles containing cheesy matter and a few bacilli.[12]
Footnote 12:
Journal of Experimental Medicine, 1898, vol. iii. p. 482.
Crookshank injected tubercular sputum into the peritoneum of a calf,
which died of streptococcus infection on the forty-second day. It showed
extensive tubercular deposits in the seat of injection and an abscess
the size of a walnut. Nodular fleshy neoplasms in hundreds studded the
mesentery, omentum, liver, spleen, and diaphragm, and small tubercles
disseminated through the lungs and liver contained tubercle bacilli.
Three abscesses contained streptococci.[13]
Footnote 13:
Transactions of the Pathological Society of London, 1891, p. 332.
The experimental inoculations of cattle with sputum by T. Smith, Kruse,
and Adami showed a decided lack of potency in the bovine system, but (1)
they do not show that the germ at once perishes in the system of cattle;
(2) they do not prove that this germ, if returned from the ox to man,
would prove less pathogenic than if carried from man to man without the
intervention of the ox. (3) The observations of Bollinger, Baumgarten,
and Crookshank show that under certain conditions the sputum bacillus
can and does produce generalized tuberculosis in cattle. (4) Diminished
pathogenesis of the germ when passed from man to cattle is no guarantee
that this germ, or the slightly modified germ of casual bovine
tuberculosis will prove equally mild if transferred from the bovine to
the human patient.
_Cases of Infection of Man from Ox._ Tscherning, of Copenhagen, attended
a young veterinarian who had cut his finger in dissecting a tuberculous
cow. The skin wound healed in three weeks, but a subcutaneous swelling
persisted, an ulcer formed, and a tuberculous mass containing bacilli
was removed. No secondary tubercles formed.[14] A parallel case occurred
to a prominent American veterinarian. The diseased tissue was excised
and the bacilli identified by the bacteriologist of the university with
which the patient was connected, and a permanent recovery ensued.
Footnote 14:
Nocard. Dictionnaire de Med. Veterinaire. Article, Tuberculosis.
Pfeiffer, of Weimar, attended a veterinarian who had been similarly
inoculated from a tuberculous cow. The patient, aged thirty-four years,
had a good constitution and no tuberculous taint. The cutaneous lesion
healed, but six months later there was tuberculosis in the cicatrix;
pulmonary tuberculosis followed, and the patient died of this two years
later. At the necropsy were found tubercular arthritis of the wounded
thumb and many vomicæ in the lungs.[15]
Footnote 15:
Zeitschrift für Hygiene, Band iii.
The post-mortem wart (tuberculosis verrucosa cutis) is familiar to
surgeons as occurring in butchers and tanners, and there is every
presumption that in many cases this is of bovine origin (Martin du
Magny, Hanot, Senn, Riehl, Paltauf, Osier). Gerber testifies that in
exceptional cases this extends to the lymph-glands and becomes
generalized.
Dr. Stang, of Amorbach, had a five-year-old, finely developed boy
patient, of healthy parents, destitute of hereditary taint. He died
after a few weeks’ illness with miliary tuberculosis of the lungs and
enormously enlarged tubercular mesenteric glands. The cow which supplied
his milk had been killed a short time before with pulmonary
tuberculosis.[16]
Footnote 16:
Lydtin. Veterinary Congress, Brussels, 1883.
Dr. Demme, of the Children’s Hospital, Berne, had four infants, the
offspring of sound parents, with no hereditary taint of tubercle, die of
intestinal and mesenteric tuberculosis, having been fed on the milk of
tuberculous cows. Among 2,000 tuberculous infants treated in twenty
years these were the only ones in which he could exclude the probability
of hereditary and other causes.[17]
Footnote 17:
Nocard. Dictionnaire de Med. Veterinaire. Article, Tuberculosis.
Mr. Howe, of North Hadley, Mass., lost a son, aged twenty months, from
abdominal tuberculosis, three months after he had paid a week’s visit to
his uncle and had been fed the milk of the uncle’s tuberculous cow. The
cow showed at death generalized tuberculosis. The child had been strong
and well, as were his parents.
The four-year-old son of Colonel Beecher, of Yonkers, died March, 1894,
of tubercular meningitis, and the two Alderney cows which had supplied
him with milk were then proved consumptive by the tuberculin test and
post-mortem examination.[18]
Footnote 18:
New York Sun, March 29, 1894.
The child of Dr. Brown, U. S. A., and now of Cornell University Medical
School, was similarly cut off by tuberculosis, having been fed on the
milk of a tuberculous cow.
Dr. C. H. Peabody had a child patient die of tubercular meningitis three
months after the family cow had been killed for generalized
tuberculosis. There had been previously no tuberculosis in the family
(Ernst, _Infectiousness of Milk_).
A. H. Rose, of Littleton, Mass., gives the case of a child which was fed
for three years on the milk of a tuberculous cow and died with abdominal
tuberculosis (Ernst).
Gordon, of Quincy, Mass., records the case of a ten months old child of
healthy parents and ancestry which had been fed on the milk of a cow
with advanced tuberculosis, and which died after a few weeks with acute
tuberculosis (Ernst).
Gage, of Lowell, Mass., had an infant patient of healthy parents and
surroundings, but which subsisted exclusively on a cow’s milk that
contained bacilli and infected Guinea pigs. The child died of tubercular
meningitis. A second child fed the same milk suffered in a similar way
(Ernst).
Andersen, of Seeland, reports the death from tuberculosis of a six
months old child which had fed on the milk of a cow having tuberculosis
of the udder. The mother developed symptoms of tuberculosis after the
death of the child.[19]
Footnote 19:
Hatch Experiment Station, Massachusetts Agricultural College, Bulletin
No. 3.
Dr. Gosse, of Geneva, Switzerland, spent his Sundays with his family on
an estate in the hills, and his daughter, aged seventeen years, took
great pleasure in drinking milk warm from the cows. Early in 1893 she
sickened with an obscure illness, and after ten months died, revealing
at the necropsy intestinal and mesenteric tuberculosis. The five cows on
the estate were tested with tuberculin; four reacted and were killed;
two showed tuberculous udders (Nocard).
Dr. H. M. Pond reports four cases of tuberculosis in one family, three
of them fatal. The cows supplying the family with milk were
tuberculous.[20]
Footnote 20:
Pacific Medical and Surgical Journal, 1888.
Dr. Faust, veterinarian, of Poughkeepsie, records the case of a family
on Long Island that lost from tuberculosis 139 cows. A three-year-old
child and two grown sons died of tuberculosis. Tuberculosis was unknown
in the parents’ families.[21]
Footnote 21:
Report to the Board of Health.
Dr. Kelly, veterinarian, Albany, gives the following: In a family of
five a son, aged nineteen years, was very fond of milk and drank it
fresh from the cow, and contracted tuberculosis. Some months later the
farm herd of seventeen registered Jerseys were tested with tuberculin,
and thirteen reacted and showed extensive tuberculosis when killed.
Dr. Cooper, veterinarian, Paterson, N. J., furnishes this: A child, fed
on the milk of a cow, contracted tabes mesenterica. Examination revealed
the presence of tubercle bacilli in the milk. The milk was then fed to
ten kittens, all of which became ill and emaciated, and when killed
showed tuberculosis.
Such cases, in connection with the experimental inoculations, furnish
more than mere circumstantial evidence. They are corroborated and
strengthened by the very uniform diffusion of tuberculosis in man and
stalled cattle in practically all civilized countries. Of the closer
connection in individual cases one or two instances may here be added as
drawn from personal observation:
1. In one case a family cow and the owner’s wife had both advanced
tuberculosis. The lady consumed a good deal of the cow’s milk, but when
she gave up its use she felt decidedly better.
2. The owner of a thoroughbred herd of sixty head had suffered for years
from consumption, and attributed the poor condition of the animals to
lack of care since he had been laid aside. Without the tuberculin test,
I diagnosed tuberculosis in fifty-nine of the animals.
3. In a second thoroughbred herd there never lacked one or two cases of
advanced tuberculosis, two of the family suffered, and the eldest son,
who was fond of milk and vegetable food, died of pulmonary tuberculosis.
4. A dairy of common cows had seventeen out of twenty-six destroyed for
tuberculosis, and the farmer’s wife, father-in-law, and two
brothers-in-law had shortly before died of consumption. The wife felt
ill in the close house air, and with her father occupied herself much
about the cattle.
5. A veterinary professor, who was meat inspector of the city abattoir,
died a few years ago of tuberculosis, which he handled so constantly in
his daily duties.
Stalker and Niles report that 5 persons, 20 to 30 years of age, of
healthy ancestry, died of tuberculosis within two years, on a farm where
17 tuberculous cattle were found, and others had died in previous years,
(Bull. Ia. Agr. Exp. Stat., 29).
Leonhardt reports the death from tuberculosis, abdominal and meningeal,
of two children, fed on the milk of a tuberculous cow, (Rep. N. H. Bd.
of Health, 1892).
Sontag reports the death by tuberculosis of a six months old child of
healthy parents, that had been fed the milk of a tuberculous cow, (Rep.
N. H. Board of Health, 1892).
Dr. E. Pearson quotes the following:
“A well known veterinarian wounded in the hand in opening a tuberculous
cow, had a tumid, intractable sore, the tissues of which when excised
showed tubercle bacilli.
A veterinarian, of Chester Co., Pa., in opening a tuberculous cow, cut
his knuckle, which healed tardily, remained swollen and when excised,
showed typical tubercular lesions including giant cells.”
He quotes from Hartzell the cases of two men wounded in cleaning cattle
cars, both of whom had resulting tubercle, arrested in one case by
excision, but in the other advanced to generalized tuberculosis and
death.
Bang gives the following Danish cases:
A merchant having two chlorotic daughters secured a fine cow to feed
them fresh milk. The cow was killed tuberculous and was replaced by
another which also showed tuberculosis, this time affecting the udder.
The girls died of tuberculosis at 16 and 18 years. Two younger children
fed on the milk of sound cows grew up healthy.
A healthy cow became tubercular, after having been placed in the same
stall in which another had died of tuberculosis. A child fed almost
exclusively on the milk of these two cows died of tuberculosis.
A peasant at Silkeborg drank freely of milk freshly drawn. He died of
tuberculosis, as did also a cow, and later in the same stable, a pig.
A peasant had an 11 year old cow with generalized tuberculosis,
implicating the udder. The wife of the peasant, formerly healthy, became
tuberculous shortly after the udder became affected and died at 45. A
daughter who, like her mother, used the milk of this cow, died
consumptive in the same year. The husband who drank beer, and not milk,
remained well.
A physician fed his two children on the milk of his tubercular cow, and
lost both from tuberculosis. Neither parents nor grand-parents were
tuberculous. (L. Pearson in Bull. 75, Tuberculosis of Cattle).
Thorne had reports from twenty-two Ohio physicians to the effect that
they had traced tuberculosis in their patients to the use of the milk of
tuberculous cows, and thirty-three who believed they had reason to
suspect the meat and milk supply as the source of cases of consumption.
(Ohio Exp. Stat. Bull. 108).
To these may be added the cutaneous forms of tuberculosis (tuberculosis
verrucosa cutis), which occur on the hands of persons (butchers,
tanners, coachmen, cooks, etc.), who handle infected products of
animals. These have been described by Riehl and Paltauf, Senn, and a
number of surgeons and dermatologists and the relation of the occupation
to the seat of the disease is conclusive as to the source of the
infection. It is the exact counterpart of the verrucosa necrogenica of
the hands of persons working in the dissecting rooms of medical schools,
and the source of infection is equally well established in both cases.
A strong argument for the appreciable influence of the bovine bacillus
upon man (acting directly or indirectly through the pig) is that the
relative death rate of Jews from tuberculosis is materially less than
that of other races. It is constantly claimed that orthodox Jews who eat
only kosher (rabbi inspected) beef and no pork, suffer least of all the
population from tuberculosis. Dr. Gerster, judging by the burial returns
of the United Synagogue and the English Registrar General’s returns,
concludes that only about half the relative proportion of Hebrews suffer
from consumption as do other races in the same country. Some remarkable
facts come out in the report of the Royal Commission on tuberculosis in
England. In England and Wales the disease had decreased 39.1 per cent,
in thirty-five years, but this decrease has been mainly in pulmonary
cases, while the abdominal forms decreased only 8.5 per cent. Sir
Richard Thorne, indeed says, that in children of the first year there
had been an actual encrease of 27.7 per cent. Northrup and Still, on the
contrary, present statistics showing that in children the pulmonary form
of tuberculosis is the most common (Brit. Med. Jour. 1898). If in the
face of this there has been a very material encrease of the abdominal
form, coincident with the notorious encrease of the disease in dairy
cows and of the bottle-feeding of infants, may we not enquire how much
of this is due to the greater prevalence of bottle-feeding and the
infected cow’s milk? It is not for a moment supposed that the majority
of infections in children come from the cow. The question is whether
this encrease in the minority is not in measure chargeable on the cow.
The impaired nutrition resulting in some instances from the use of cow’s
milk cannot well be charged with a marked encrease of cases in which the
mesenteric tubercles point so directly to infection through the food. If
it is held that the tubercle bacilli in the milk are harmless, we wait
for evidence of the real cause of such encrease and localization.
The experiments of Adami show that tubercle is directly transmissible
from man to ox though usually with decreased virulence. More recently,
Ravenel using the bacillus derived from the mesenteric glands of a
child, injected intravenously two tuberculin-tested calves, with 5cc.
each of the culture producing exalted hyperthermia, miliary tuberculosis
of the lungs, tuberculosis and caseation of the bronchial and
mediastinal glands, and death in 17 days. Dr. Garnault’s experiment on
himself, now in progress, has already shown the great danger to a
susceptible man, of the bovine bacillus.
As showing accommodation to environment, Battaillon and Ferre found that
the bacillus (mammalian and avian) grown in frogs, Dubard that grown in
fishes, Kráhl that grown in frogs, snakes, fishes and lizards, and
Müeller that grown in the glow worm, thereafter grew at summer
temperature (68° F.) and grew poorly or not at all in the bodies of
mammalia.
The tubercle bacillus is primarily and essentially one, but this must
not close our eyes to the fact that in different hosts and environments
it takes on very different habits, so that for the time and in these
surroundings, it is materially modified in its pathogenic attitude
toward different races. Yet its ready variability when conditions are
favorable to change, renders it desirable to destroy it in all its
forms, and especially in those which approximate most closely to those
that prey on man and animals.
An impartial review of the whole field warrants the conclusion that the
nineteen young (and therefore comparatively insusceptible) cattle which
in Koch’s hands failed to develop generalized tuberculosis after
inoculation with the virulent sputum of man, and the smaller numbers
that resulted in the same way under similar treatment in the hands of
Th. Smith, Dinwiddie and Adami, while showing a very marked limitation
in the susceptibility of the sound bovine system to weak bacilli from
man, cannot disprove the many well authenticated cases of the
transmission of tuberculosis from cow to man and the reverse. The
greater potency of the bovine bacillus over that of man, in its action
on the small rodents and pigs, utterly forbids the unproved assumption
that it is on the contrary harmless to man.
If the object of the sanitarian were merely to delay a fatal result in
his tuberculous patient, while he accepted the prevalence of
tuberculosis as inevitable for all future time, the acknowledged
lessened receptivity of the ox for the bacillus from man would mean more
and would be at least worthy of a hearing, but as the extinction of a
disease germ and its representative plague must ever be the first
object, any movement toward the preservation in cattle of a germ which
is deadly to man and much more so to cattle, must be held as subversive
of the prime purpose of sanitary work. This is true even if we allow,
for the sake of argument, that only a few of the bovine bacilli are
capable of dangerously colonizing the human body, and that special
environment is needful to allow of such successful colonization. On the
other hand the limited receptivity of the ox for the bacillus from man
is the greatest encouragement to active work to exterminate tuberculosis
from our herds. It is impossible to adopt in man the summary measures
that are so successful in the speedy _stamping out_ of the plagues of
the lower animals, so that tuberculosis in the human family can only be
eradicated by slow degrees, and therefore there will long continue for
our herds the danger from the human side, but just so far as the
susceptibility of cattle to human tuberculosis is limited, in the same
ratio are our hands strengthened in effective work for the extinction of
consumption in our herds and for preserving their soundness after they
have once been purified. If they were to be reinfected by the presence
of any consumptive person we might well despair of success in face of a
wide prevalence of tuberculosis in man, but since it is only
exceptionally that cattle suffer from man, outbreaks coming from this
source can the more easily be taken care of. In this view tuberculosis
is approximated somewhat more closely to the other bovine plagues (lung
plague, rinderpest) which can be stamped out with the greatest ease and
certainty, so that as a purely economic measure the argument for the
speedy extinction of tuberculosis in our herds is reinforced.