George E. (George Ensigh) Bushnell.

A study in the epidemiology of tuberculosis with especial reference to tuberculosis of the tropics and of the negro race online

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APR 8 1971



Epidemiology of Tuberculosis

With Especial Reference to




sr BY

Colonel, United States Army (Medical Corps) retired. Honorary Vice-

President and Director National Tuberculosis Association of the United States.

Member American Climatological and Clinical Association.





Printed by

Hamilton Printing Company
Albany,N. Y.


To understand tuberculosis of the temperate zone and of
our race it is necessary to know something of tuberculosis
as it affects other races which live under different social,
economic and climatic conditions. No apology is therefore
needed, it is hoped, for this little book, although the views
as to tuberculosis set forth in it are not supported by any
original investigations of the author. The aim has been,
rather, to collect and discuss facts and in so doing to make
known to the English-speaking public some of the very im-
portant but little known epidemiological data which have
been published in widely scattered and often more or less
inaccessible periodicals and, the greater part of them, in
foreign tongues. With this end in view the writer has not
scrupled to make copious extracts of papers on the epidemi-
ology of tuberculosis, mostly from the German, for the
translation of which he assumes the responsibility.

The work in its first draft was an essay on tuberculosis
of the tropics and of the negro race. It has outgrown its
original framework, but it has been thought best to retain
the references to the tropics, especially those which have a
practical bearing upon prophylaxis, treatment and the like.
While the principal object of the writer has been to further
the acceptance of certain views of universal applicability in
phthisiology, he has also borne in mind the need which
exists of a greater clarity of the conception of tuberculosis
as a practical problem affecting races as yet not fully tuber-
culized and hopes that what he has written may serve, not


so much as a formal treatise on tuberculosis, but rather as
a study which by emphasizing certain important but too
much neglected distinctions may stimulate inquiry and may
also prove of some practical benefit to the physicians who
encounter the disease in remote regions. The tuberculosis
of the civilized negro has been discussed in some detail, not
simply because of its interest as an epidemiological study,
but also on account of its practical importance to the citi-
zens of the United States.

Great difficulty has been experienced in determining
what the truth is as to the prevalence and severity of tuber-
culosis in various parts of the world. With regard to some
countries it has proved impossible to form any conception
as to what the actual facts are. No attempt has therefore
been made to report upon all tropical countries there is
little use in repeating statements that tuberculosis
" rages " here or there, if no further information is fur-
nished. It is the way of the epidemiologist to write pessi-
mistically on tuberculosis, as if something could be gained
by creating alarm. But this is not the standpoint of the
writer. If tuberculosis is really ravaging the world and
if nothing can be done to restrain it as a world-plague, the
proper course is to dismiss the unpleasant subject from
one's mind as completely as possible. On the other "hand,
if there is a prospect of improvement rather than of dete-
rioration and the experience of the last half -century
should encourage us to believe that this is the case every
one interested in the prevention of the disease should be
anxious to lend a hand wherever possible.

The suggestions as to a practical program in the epi-
demiological study of our own communities, as well as those
of other peoples, are submitted with much diffidence with a
view to stimulate thought and investigation.


The role of the von Pirquet test in the epidemiology of
tuberculosis is destined, it is believed, to become of increas-
ing importance. Especial attention has therefore been
paid to it in the hope that the Anglo-Saxon may be inspired
by the example of the French and of the Germans to make
use of it on a large scale not only in the tropics, but
also at home.


The Pre-Kochian Era

The Modern Era

Tuberculized Races

Non-tuberculized Races

Modes of Infection

Pathology and Pathological Anatomy

Diagnosis, especially Tuberculin Diagnosis

Prophylaxis of the Non-immunized

Treatment of Tuberculosis in the Tropics

Tuberculosis of the American Negro and of the American



Epidemics of Tuberculosis

Some Practical Considerations

Summary and Conclusions

Epidemiology of Tuberculosis


It is difficult for us who have so long known that tuber-
culosis is a transmissible disease to place ourselves in the
position of the practitioners of previous generations who
for the most part believed it to be non-infectious. It is
true that in countries like Italy where the disease was com-
paratively rare, it was believed to be highly infectious, but
this belief originated there rather in the fear of an un-
familiar malady than in any definite pathological concep-
tion. Early medical writers differed greatly among them-
selves as to this point, but on the whole the verdict was
against the infectiousness of the disease. Laennec 1 speaks
of the contagiousness of tuberculosis as very doubtful and
cites the familiar facts as to the absence of infection among
those who nurse the tuberculous but goes on to say that
many facts also show that a disease which is usually not
contagious may become so under certain circumstances.
Even Villemin's experiments which to our minds definitely
prove the infective properties of tuberculous sputum and
tissues were not frankly accepted in such a way as to influ-
ence medical practice. For example, Flint states as late as
1873 : " The doctrine of the contagiousness of the disease
(tuberculosis) has now as hitherto its advocates but the
general belief of the profession is in its non-communicabil-
ity." 2 As von Behring says the decisive victory of Ville-

1 Cited by Von Behring, Beitr. z. Experimejitellen Therap. Heft 11, p.
1 Austin Flint, Practice of Medicine, 1873.


min's doctrine was gained only after the discovery of the
tubercle bacillus. 1 The problem then was to account for a
disease consumption which was not due to infection
and which had its seat in the lungs. What more natural
under the circumstances than to class it with other respira-
tory diseases, bronchitis, laryngitis, pneumonia. These
diseases according to the prevailing view were non-infec-
tious and were caused by exposure to the weather, and
especially by sudden chilling of the surface of the body;
consumption therefore was to be regarded as brought about
in the same way. To explain why all who were subject to
exposure did not fall a prey to the disease the assumptions
of a hereditary predisposition and of an acquired cachexia,
or, as Flint puts it, of a diathesis whether always innate or
in certain cases acquired, became necessary. But the im-
portant point in the present connection is that the prom-
inence which has been given to climate as a curative agent
depended primarily upon the assumption that pulmonary
tuberculosis as a disease of the lung is originally caused and
is influenced in its progression by meteorological influences
like the other diseases of the lungs the most conspicuous
clinical symptoms of which are cough and expectoration.
Hence the use of cough medicines and of derivatives, the
warm seat by the fire, the window tightly closed to keep out

Joseph A. Gallup in Remarks on Pulmonary Consumption
which are appended to his " Sketches of Epidemic Disease
in the State of Vermont from its first settlement to the
year 1815 " expresses the opinion that conditions of hard
labor and scanty fare do not produce so many consumptions
as indolence and luxury. Upon the same principle, he says,
much riding and milk diet or low regimen have been found

1 Loc. cit.


useful oftentimes in the cure and prevention. By low
regimen Gallup meant bread and milk alone or combined
with a vegetarian diet. " In certain very low states how-
ever and also after hope of recovery is relinquished, if the
patient should have a particular desire for more nourishing
food as meat, oysters, etc., he may be indulged." Venesec-
tion should be employed more or less extensively according
to the severity of the case. " The author has frequently
treated cases of phthisis of delicate habit by bleeding with
advantage beyond his most sanguine expectations." After
the proper curative means have been used a sufficient length
of time moderate exercise may give relief. To receive
permanent benefit it should be almost constantly employed
even to the point of fatigue. This heroic treatment was
probably about the same as that which the author would
have employed in gouty bronchitis. Evidently he conceives
of consumption as an analogous disease. It appears from
some of his remarks that his methods had received criticism
by physicians of the newer school. As to etiology he says :
" The disease appearing chiefly in certain districts in the
same latitude gives a strong presumption that some dele-
terious elementary principle is necessary to its production.
Its appearing mostly in the middle latitudes is presumptive
that the extreme and sudden changes of temperature from
heat to cold and the reverse have a controlling influence."
We may paraphrase this somewhat obscure utterance as
follows: Since whatever the ultimate cause of consump-
tion may be the disease prevails more in certain districts
than in others, in view of its non-contagiousness the ob-
served differences as to prevalence are best explained by
ascribing them to meteorological conditions. But con-
sumption is more prevalent in the temperate zones than
elsewhere. The distinctive characteristic of these zonea


from a meteorological point of view being a wide range of
temperature with rapid alternations, it is the sudden
changes of temperature that govern the appearance of the
disease. The succinctness of the author's statement of his
views and the absence of argument in their support show
that he believed that he was expressing the prevailing
theory of his day, and felt no need of explaining in what
way vicissitudes of temperature could have so serious re-
sults. Evidently his opinion is that consumption, like other
respiratory diseases, is due to " taking cold."

But when at a later date it became necessary to explain
how it was that consumption was so serious a disease in the
mild and equable temperature of the South Sea Islands
alternations of temperature could no longer be advanced as
the cause. It is now the imprudence of the sick man that
is to be blamed. Gallup would never have dreamed of say-
ing that the greater prevalence of consumption in certain
parts of the United States was due to the fact that the
inhabitants of those districts were especially careless about
wet feet or about sitting in draughts. But what would
have been absurd if said of a homogeneous people in whom
a certain average degree of prudence is to be assumed
seemed quite in place when applied to a foreign race to which
the author holds himself superior. Turner writing of the
Samoa of 1868 says : " Chest affections of all kinds, cough,
asthma, bronchitis, phthisis, etc., are very frequent. This
is to be accounted for principally by the extreme careless-
ness of the natives sitting down right in a strong draught
in order to cool off or exposing themselves to the injurious
night dews which are so heavy in these islands." 1 Rochard
writing in 1856 likewise considers chilling of the body a

'Notes of Practice in Samoa, Glasgow Med. Jour. Vol. 2, 4th Seriei,
1869-70, p. 502.


cause of consumption. " The majority of deaths at
Tahite," he says, " are due to pulmonary phthisis which
kills with extraordinary rapidity. Its ravages among the
natives are explained by their mode of life, the insufficiency
of their clothing, their habitations open to all winds, the
abuse of cold baths, their recklessness when ill and above
all their incredible libertinage." 1 Another medical writer
sets himself the difficult task of explaining the relative
prevalence of tuberculosis and of disease in general.
Dutroulau 2 in his works published in 1858 and in 1868 on
the climatic conditions of the various French colonies treats
especially of the effect of tropical climates upon the French
of the military and naval establishments and the colonial
civil officials, classes which are admitted into colonial hos-
pitals and figure in the government reports. As for pul-
monary tuberculosis he says, rare at Senegambia and
Mayotte, where the reign of epidemics comprehends all the
pathology, it figures notably in the statistics of all the other
hospitals and there is no medical report that does not em-
phasize the fatal influence of the climate upon the rapidity
of its course. For him the more or less sudden, more or
less great variations of temperature in hot countries are
only the accidents of meteorology and do not constitute its
pathological action which resides in the constant elevation
and the slight variability of the averages (of temperature,
humidity, etc.). A sense of suffocation arises from the
efforts of respiration necessary to compensate by quantity
for the lesser oxygenation of the air inspired, efforts that
result in fatigue and in the continual excitation of the pul-
monary tissue, that is to say, in organic debility and mor-

1 Memoirs de I'Acadgmie de Me'decine. Vol. 20, 1856, p. 75.

* Trait6 des Maladies des Europe'ens dans les Pays Chauds. Paris, 1868,
p. 104. Topoigraphae MMicale d'e Climate Intertropicaux. Paris, 185,
p. 120.


bid activity. Let there be some perturbation of the new
functions which have devolved upon the skin (as from
changes of temperature we will suppose) and immediately
the effect is felt in the internal organs; the germs of dis-
ease which they contain receive an impulsion which hastens
and activates their symptomatic explosion. But, he
hastens to add, the fact must not be lost sight of that the
physiological modifications in the functions of the lung and
skin are due to the elevation and non-variability of the
meteorological elements much more than to their variations.
Otherwise one would not understand why in Senegambia
where the variations of humidity and of temperature are
carried to an extreme pulmonary tuberculosis is little heard
of while at Cayenne where the variations are imperceptible
and the average always high the disease develops and pro-
gresses with remarkable rapidity. Other observers may
think that atmospheric changes are the cause of disease but
Dutroulau evidently prides himself on his ingenious solu-
tion of the problem : " Why is Cayenne worse for con-
sumption than Senegambia " ? and specifically calls the at-
tention of physicians to his view which he says differs from
that of others. The difficulties however are not all re-
moved. He had given humidity as one of the causes which
really underlie the pathology of tuberculosis. Now
Cayenne is one of the most humid spots in the world while
Senegambia on account of the proximity of Sahara is rela-
tively dry. The unwary might think that the humidity of
Cayenne accounted for its inferiority, certainly in these
days of the reign of bacteriology that is what we should
conclude. But the ingenious author is not to be caught so
easily. He remembers ffhat he must provide for the fact
that the heights of volcanic islands are more humid and
more rainy than the plains but nevertheless are more


healthful, which he says they owe to the nature of their
soil. " The hygrometric state of the atmosphere is only a
direct and powerful cause of insalubrity in relation to the
geological nature of the soil ; the vapor of water dissolves
the miasms." With the aid of this obscure ally every path-
ological situation might, it would seem, be explained, but
it is much easier to frame a theory that will account for the
relative healthfulness of two countries than one that will
fit everywhere. There is Cochin-China, for example, to be
reckoned with, Cochin-China which he says seems an ex-
ception to all rules. For there it is not the wettest time
of the year, when (the reader would suppose) " the
miasms " would be dissolved with especial facility that is
the most unhealthful but the second quarter when the rains
are just commencing. " The first impregnation of the soil
by the waters is doubtless the cause of this phenomenon,
also the first appearance of the southwest monsoon."

Another Frenchman writing at about the same time as
Dutroulau was reaching very different conclusions. Jour-
danet 1 had to account for the fact that in the towns of Cam-
peche and Merida in Yucatan tuberculosis is an acute affec-
tion which kills quickly while in Tabasco the disease is rare.
Now Tabasco lies in a swampy region while Campeche and
Merida are built upon a dry and calcareous soil. Evidently
then, Jourdanet thinks, the dry and calcareous soil must be
unfavorable for phthisis and he fortifies his position by the
statement that it was once the custom to send the phthisi-
cal from Campeche and Merida to Valladolid, a town of the
interior on a damp site and surrounded by rank vegetation,
experience having shown that the course of phthisis was
less acute there.

The foregoing examples illustrate the contradictions

1 Le Mexique et FAm6rique Tropieale, 1864.


which result when general conclusions are drawn from lim-
ited observations as to the influence of climate.

Hirsch 1 is the most prominent early systematic writer in
the domain of geographical pathology. The second volume
of the first German edition of his Handbook was published
in 1862-1864. He recognizes the unsatisfactory nature of
much of the enormous mass of data that he had collected
and the unscientific way in which observations as to the
influence of climatic conditions upon consumption have
been made, and condemns the generalizations which are so
frequently made from insufficient data as fatal for* the
study of the etiology. If one would throw light upon this
dark subject, he says, it will be necessary to remember that
in the genesis of consumption as in most of the other non-
specific forms of disease we have to do not with one definite
pathogenic factor but usually with the combined action of
several more or less directly pathogenic factors. The mis-
take of over-emphasizing one factor at the risk of under-
estimating the importance of the others is made by those
who give so much weight to purely meteorological condi-
tions. Climate can not be the essential factor, for con-
sumption has appeared in many localities which had for-
merly been spared without there having been any change
in climatic conditions. The mean level of the temperature
has no significance for the frequency or rarity of phthisis
in any locality, and temperature-changes are important only
in their effect upon the humidity of the air; they have no
etiological importance when the air is absolutely dry. Just
as very moist air is an important causal factor in catarrh
and bronchitis so also is it for consumption, those countries
which have the most consumption being distinguished by a

'Handbuch der Historisch-geographischen pathologic. 1st German Edi-
tion, 1862-64, Vol. 2, p. 74.


high degree of humidity, those on the other hand which
possess an immunity from the disease having mostly a sur-
prising dryness of the air, or, with average moisture, a
very equable temperature. Climate and weather have in-
fluence upon the occurrence or the geographical extension
of tuberculosis in so far only as they are influential in pro-
ducing directly or indirectly more or less continuous and
severe irritation of the respiratory organs, especially the
lungs, as the result of which there first appears catarrhal
affection of the organ which with continuance of the nox-
ious influence becomes a locus minoris resistentiae and,
in the presence of a predisposition otherwise induced, a
focus of the morbid process. Elsewhere he says summarily
" The source of the disease is to be sought in social not in
meteorological conditions." The predisposing causes
Hirsch finds in denseness of the population to which, ceteris
paribus, the frequency of tuberculosis is directly propor-
tional, further in sedentary modes of life with the resulting
loss of exercise and of fresh air. Uncivilized people when
they come first into contact with Europeans imitate their
mode of life and receive physical harm by so doing. Some
races, as the negro race, have a racial predisposition. He
denies that the geological formation or the character of the
soil has any importance in the causation of tuberculosis.

Consumption then in his definition is a non-specific dis-
ease which attacks a lung already damaged by injurious
atmospheric influences provided that a (very ill-defined)
predisposition is present, which predisposition is in some
way connected with density of population and a sedentary
life. Nothing could better illustrate than this definition
the difficulties under which our fathers labored in their
endeavor to account for the course and dissemination of
tuberculosis considered as a non-infectious disease.


It is unfortunate that the manner in which tuberculosis
comported itself when first introduced among an absolutely
uninfected race could not have been carefully studied by
skilled observers. The islands of the Pacific, on account of
their isolation, would have been peculiarly favorable places
for such study. But the first dissemination of the disease
took place in the days when tuberculosis was not believed
to be infectious. Captain Cook rediscovered the Sandwich
Islands in 1778 and no ship has visited the islands of the
Pacific since his day that has not borne with it the seeds of
disease to these scattered peoples, who are probably all now
more or less infected with tuberculosis, however great their
isolation. Naturally no ship captain thought for one mo-
ment of such a danger, and if it had ever occurred to any
one of them as a possibility, neither he nor indeed, for that
matter, the large majority of the physicians of the present
day would have conceived the idea of danger of contagion
from the healthy members of the crew who were bacillus-
carriers, while no articles given in barter would have been
considered potential sources of infection unless they were
known to have been used by a consumptive. So that what-
ever other infections they may have bestowed no doubt the
crews of the ships that had left the fatal gift of tubercu-
losis sailed away with a perfectly clear conscience so far as
that disease was concerned. Of course early visitors to the
tropics soon noted that consumption did not prevail among
the natives. Hence the natural inference that since the
disease was due to climatic influences, the climate of the
place which showed so singular an immunity would be bene-
ficial for those who were already affected with it. As a
result of this view European consumptives were encouraged
to visit the tropics in order to reap the advantages of the
climatic conditions. The Catholic sisters in the French


Congo, for example, imported from Europe many of their
order who had tuberculosis in the hope of curing them. But
the results of this experiment, according to Gamier, were
disastrous. 1 When in later years the disease had become
disseminated through the native populations, on account of
the prevailing view of its non-communicability the facts
were necessarily interpreted not as an evidence of the infec-
tiousness of tuberculosis but as showing that the former
observation as to its absence must have been erroneous. It
may appear singular at first sight to one who reads Dutrou-

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Online LibraryGeorge E. (George Ensigh) BushnellA study in the epidemiology of tuberculosis with especial reference to tuberculosis of the tropics and of the negro race → online text (page 1 of 17)