ETIOLOGY.
There is hardly anything on earth, or between it and heaven, which has
not been regarded as the cause of Leprosy; and this is but natural
since the less one knows, the more actively does his imagination work.
And since all that was known of Leprosy was that it was a loathsome
disease, search was made everywhere for a cause. We will not linger
over the older literature of Leprosy. That may be found fully dealt
with in Danielssen and Boeck’s _Traité de la Spedalskhed_ and in
Hirsch’s _Geographical Pathology_.
Only after the work of Danielssen and Boeck can one say that Leprosy
entered the ranks of the scientifically investigated diseases. At
that time, in 1840, when they commenced their investigations, Humoral
Pathology held the field. Most diseases were ascribed to changes in
the blood, and they therefore endeavoured to establish that there was
in lepers a change in the blood which they regarded as the cause of
the disease symptoms, especially the node formation. These changes
in the blood they believed were caused by unfavourable conditions of
living, and as they were not able to find any convincing evidence of
the power of infection of the disease but several of its limitations to
certain families, they drew the conclusion that Lepra, as they called
it, might appear spontaneously, that is to say, that the sanguineous
dyscrasia which led to leprosy could be developed under unfavourable
conditions of life, but that it was in most cases hereditary. It must,
however, be noted that Danielssen always regarded Leprosy as a specific
disease, described it as such, and sought for a specific cause, and
the fact that he did not find it must be ascribed to the circumstance
that microscopical technique and microscopical aids, especially the
immersion lens, were at that time either insufficiently developed, or
not yet discovered. The teaching of Danielssen and Boeck was everywhere
adopted, especially their view of the heredity of the disease. The fish
diet and damp cold theories are only attempts to explain the so-called
spontaneous development of the disease, and they are founded on the
fact that Leprosy is chiefly present in littoral districts and on
islands.
Of other Norwegian investigators, the late Dr. Hjorth held the view
that Leprosy could not be ascribed to a specific cause, and that it
was certainly not hereditary. Dr. Holmsen regarded it as a specific
miasmatic and non-hereditary disease, and finally Prof. Lochmann stated
that it was specific, contagious, and hereditary. While Danielssen
and Boeck always required a leprous ancestor in order to recognise a
case as hereditary, and when this was not forthcoming, found in the
presence of the disease in other branches of the family, proof of its
heredity, Biedenkap, as he was unable in many of his cases to determine
the existence of leprous ancestors, widened the definition of heredity
by assuming that unfavourable conditions of life might produce in the
organism conditions which became hereditary, and showed themselves in
later generations as leprosy. In the year 1869, Dr. Drognat-Landré
published a book with the title, _De la contagion seule cause de la
propagation de la lépre_, in which he sought to prove that heredity had
nothing to do with the spread of Leprosy. That is, according to our
view, the right standpoint, as we shall endeavour to demonstrate.
As is seen from the above short summary of the views of Norwegian
investigators, some maintain the non-specific origin and heredity of
the disease; one only, the non-specific origin; one a specific cause
and no heredity; and finally, one a specific cause, contagiousness and
heredity.
It is rather remarkable that supporters both of the specific and the
non-specific origin of the disease should regard it as hereditary.
It apparently struck none of them that possibly the specificity of
a disease, that is, its development through the action of a poison,
might be incompatible with heredity. Since the discovery of the
Lepra bacillus and its recognition in all leprous products, it is
now everywhere admitted that it is the cause of the disease, and it
would therefore be superfluous to indicate which of all the symptoms
of the disease point to its specific nature. All this was shown in a
communication made by one of us to the Copenhagen Congress in 1884.
We start then from the assumption that Leprosy is a disease caused by
the Lepra bacillus, although it is as yet not strictly scientifically
proved, since inoculation on man and animals has not been definitely
successful.
The question as to heredity now is, Can the lepra bacillus be conveyed
by heredity. This is Baumgarten’s view; he holds that both Tuberculosis
and Leprosy are thus spread, that the bacilli of both diseases may be
transferred to the children and there remain dormant, but that they
can thence be conveyed to another generation, and from it to a fourth,
fifth, etc. generation, and then in the third, fourth, etc. generation
become once more active and cause the disease. We see at once that
this is only a modification of Biedenkap’s heredity, a peculiarity of
the organism which finally becomes evident as Leprosy. In place of
his undiscovered peculiarity, we have undiscovered latent bacilli.
Baumgarten’s view is therefore only a hypothesis for the explanation of
the origin of the two diseases. The hypothesis may be tested from two
points of view: first, we may sift it theoretically; and secondly, we
may investigate whether it can explain the distribution of the disease.
We must first endeavour to make clear _what heredity is_. As a matter
of fact we do not know; we are familiar only with a series of phenomena
which we call heredity, just as we have a series of phenomena which
we ascribe to the force of gravity, without knowing what gravity or
its force actually is. If we consider only the phenomena of heredity,
which are nowhere so completely and clearly put together as in Darwin’s
works, we find that he presents so-called laws of heredity, that is,
he has noted the most frequent phenomena of heredity, and thence
deduced a law. If the phenomena in the conveyance of a disease to one’s
descendants are to be called heredity, they must correspond with the
rest of the phenomena of heredity. And looked at thus, we know of no
specific disease which can be called hereditary. The conditions which
are hereditary are all anatomical and physiological peculiarities of
the organism. A bacillus which is living in the organism cannot be
regarded as one of its anatomical or physiological peculiarities; it
is a parasite. Now it is beyond doubt that parasites may be conveyed
from parents to children. Such are the _Achorion Schönleini_, and
the _Acarus Scabiei_. But this is no hereditary communication, it is
simply a present from the parent to his child. But, it is objected,
if the parasite is conveyed through the organs of generation during
copulation, then it is no longer a present or an inoculation, it
becomes hereditary. This appears to us a remarkable argument, that
conveyance by means of the organs of generation can change the nature
of the parasite and convert it into an anatomical constituent of the
organism of parent or child. A parasite remains always a parasite, and
since its conveyance from one adult to another is called infection, we
cannot comprehend why its conveyance to an ovum or a fœtus should be
indicated by another name. Were Baumgarten’s hypothesis correct, it
should certainly be called a hypothesis of latent infection, and not
a hypothesis of heredity. We said above that we knew of no specific
disease which was hereditary. To this it will naturally be objected
that syphilis is a typically hereditary disease. But we reply that
syphilis is a disease communicable to children, but that it is not
hereditary, and in order to maintain this statement we only need
to place in parallel the phenomena of the conveyance of hereditary
peculiarities and those of the communication of syphilis to children,
in order to make it perfectly clear how different the two methods are.
CONVEYANCE OF HEREDITARY CONVEYANCE OF SYPHILIS
PECULIARITIES. TO CHILDREN.
1.--The hereditary peculiarity
is usually limited to one
sex, so that the male communicates Not the case in syphilitic
his peculiarities to children.
his male descendants, and the
female hers to the female.
2.--Very often, possibly
always, the appearance of In the communication of
the hereditary peculiarity is syphilis to children this is
limited to a definite age. unknown.
3.--Atavismus, or the overleaping
of one or several Never known.
generations of the heredity
is very frequent.
Anyone who will maintain that these two forms of conveyance are the
same, and both hereditary, must evidently sacrifice facts.
We hold then, that a specific disease may be conveyed to the children,
but that it is never hereditary; the communication is by infection.
And since we regard leprosy as a specific disease we hold that it
cannot be hereditary. There remains, however, the further question
whether it can be conveyed to descendants by latent germinative
infection. This cannot _a priori_ be denied, although we have no
right to assume it from our knowledge of the lepra bacillus and of
the occurrence of the disease. We have indeed sought above to point
out the possibility that the lepra bacillus is attenuated in the
maculo-anæsthetic form of the disease; but we know of no phenomenon
which would allow us to assume that the bacillus could occasionally
become quite innocuous, and call forth _no_ symptoms of disease.
All this, however, proves nothing against the hypothesis; and it is
always a dangerous thing to use a simple absence of knowledge either to
contradict or to found a hypothesis.
But we think we can supply an almost incontrovertible proof that
Baumgarten’s hypothesis is wrong. It is well known that the Belgian
Father Damien became a leper in the Sandwich islands. If the Father
was of pure Belgian ancestry, and his disease was caused by latent
hereditary bacilli, then these bacilli must have been at least several
hundred years old, unless one assumes that one of his nearer ancestors
had had connection with a leper, and that in this way the Father had
acquired his bacilli. Against this is the explanation that the Father
who tended the lepers on Molokai, with self-sacrificing love, was,
through some want of care or caution, infected as he went in and out
among the lepers. The choice between the two explanations does not
appear to us a difficult one.
The view of the non-communication of leprosy by latent bacilli is
further strengthened by the fact that there are places in Norway where
many descendants of lepers live without one single one of them becoming
leprous, as for example, in the town of Bergen where the descendants
of lepers may certainly be numbered by thousands; and further, we
have demonstrated by our investigations in North America, that of the
numerous descendants of Norwegian lepers there, not one has developed
the disease. But since about one hundred and seventy leprous Norwegians
have emigrated to America, it may possibly be that the disease is
spread by infection. There are indeed cases in America which have
possibly arisen from infection, but they are not sufficiently definite
to serve as arguments for its contagion. But even if leprosy be a
contagious disease, one can easily understand how it should spread
little, or not at all, in North America, when one compares the social
condition and especially the cleanliness there with that in Norway, and
probably especially with that of the districts in which leprosy is most
prevalent. In North America the dwelling houses are roomy, so that the
lepers whom we saw there had usually their own room, or at least their
own bed; and everywhere, even among the Norwegians, great cleanliness
is observed. And this is, according to our view, sufficient isolation
in order, in most cases, to prevent the spread of the disease.
That leprosy is really contagious is primarily evident from its nature
as a bacillary disease. No one has been able to demonstrate the
presence of the bacillus outside the human body, so that we may abandon
the idea of a miasmatic origin.
Unfortunately, all attempts to inoculate animals have failed. The now
old experiments of Neisser and Damsch, as well as our own, we may pass
over. We dealt with them in our Copenhagen communication. Since then
Melcher and Ortmann believe that they have communicated the disease to
rabbits. Dr. Ortmann has kindly sent us preparations from the infected
rabbits, and on close examination of them we regret to say that we
lost our faith in the leprous nature of this affection of rabbits. We
found both caseous degeneration and myelo-plaques in the preparation,
which, as we have noted, we have never found in leprosy. At the same
time the affection does not look exactly like tubercle, and it is
possible that in rabbits leprosy appears otherwise than in man. But we
may note that Veterinary Surgeon Nielsen has, here in Bergen, observed
a disease in mice, which shows a close resemblance to Ortmann’s rabbit
leprosy. Inoculated on a rabbit, the disease appeared with new growths
in the cœcum, just like Ortmann’s rabbit leprosy. These new growths
had certainly more resemblance to tuberculosis; but there were in them,
at many places around the vessels, cells, crammed full of bacilli.
Nielsen’s investigations are not yet concluded, but it is possible that
the disease is one of animals as yet unknown, which Melcher and Ortmann
have by chance conveyed to their rabbits. All the inoculations of
leprosy on rabbits which Dr. P. F. Holst made in the laboratory of the
Lungegaards Hospital were unsuccessful; not one of the infected animals
became leprous.
Although, as we have stated above, the lepra bacillus has never been
found outside the human body, this might possibly be dependent on
insufficient search, and it might be possible that the old view at
present maintained by Hutchinson is the right one, viz., that leprosy
is caused by the eating of putrifying fish, or that the contention of
Holmsen that leprosy is a miasmatic disease, is correct.
Against Hutchinson’s hypothesis there is in the first place the fact
that we have never succeeded in cultivating the bacillus, which, if the
bacillus lived as a saprophyte on decaying fish, would be a very simple
matter. And there are, secondly, places where the inhabitants certainly
and frequently enjoy decaying fish without the disease appearing. And
thirdly, there are many places authoritatively indicated where leprosy
is present, and where no fish is ever eaten. For his hypothesis of
the miasmatic origin, Holmsen can only bring forward the fact that
the disease is often limited to certain districts. This is certainly
correct, but this endemic appearance of leprosy may be as readily
explained by infection, while the localities affected do not give the
slightest support to the assumption of a miasma. Such areas are found
here in Norway, both on the bare cliffs, on the coast, in the valleys,
and on the mountains.
There is, therefore, no other course open to us but to assume the
infectiousness of the disease, and thus the spread of leprosy
is readily understood; while by the assumption of heredity, or
Baumgarten’s latent germinative infection, it remains absolutely
inexplicable. These two last causes are to our thinking absolutely
proved to be non-existent by the case of Father Damien; by the results
of our investigations in North America; and by the diminution of the
disease in the descendants of lepers in the Norwegian towns.
But _direct proofs_ of its contagiousness may also be obtained. Such
are given by Drognat-Landré in his book, and also by many other
observers. Norway can supply many proofs; but against these it can
always be urged that it is impossible to exclude the possibility of
inheritance on account of the widespread nature of the disease. But we
think we can supply from Norway a still better proof in the shape of
the gradual diminution of the disease during the last thirty-five to
forty years.
Up to 1856 leprosy probably increased in Norway; we cannot speak more
definitely, as previous to that year there was no exact or sufficient
enumeration of the lepers. But we have grounds for believing that we
have obtained, by means of the yearly census begun in 1856, a pretty
exact knowledge of the number of new cases in the years 1851-55,
and this shows that the number is considerable, and almost exactly
corresponds with the number of new cases in the next five years,
1856-60. This, we think, indicates that the total number of lepers in
the two quinquenniums was pretty much the same. Now we know that there
were in Norway in 1856 over 2800 lepers. The number was estimated
in 1836 at 659, and in 1845 at 1122. According to this estimate a
considerable increase had taken place. We can, however, with certainty
say that the numbers for 1836 and 1845 are too low. In the first place,
the enumeration was not undertaken by medical men, and secondly, even
now, there are many lepers overlooked at every enumeration, or, to
speak more correctly, they are not discovered because the patients
conceal their condition. But that the number of those overlooked in
the years 1836 and 1845 can have been so great as the difference
between the numbers for those years and that for 1856 is scarcely
credible, and it therefore appears probable that the number of lepers
in Norway increased during the first half of the century.
In the year 1856 the first Leper Asylum was opened in Bergen.
Previously to this we had in Bergen the St. Georg and Lungegaard’s
Hospitals, which together served for 200 patients. In Molde there was
also a small hospital, for lepers, so that altogether in the year 1856
there were about 235 lepers in hospital. In 1861 were opened two new
asylums, one in Molde, the other in Trondhjem (Drontheim), and as is
seen in TABLE IV (p. 145), since that time a large number of lepers
have been admitted to these institutions.
We may regard the numbers in this TABLE up to 1885 as accurate; for
the later years corrections will have to be made from the later
enumerations, which may detect older, concealed cases. But these can
only affect the figures to a limited degree.
If we consider the TABLE closely, we see that in the first quinquennium
(1856-60) the total number of lepers is 76 less, while those in their
own homes are 380 less; during this period 585 lepers were admitted
to the asylums. The number of lepers as a whole, then, was not much
reduced, but at the end of the period there were 380 lepers fewer
at home, or, in other words, there were among the people 380 fewer
sources of infection, and to this we ascribe it that while the number
of new cases was 1,148 in the years 1856-60, it fell in the years
1861-65 to 1,028. The mortality of the year 1856 we do not know; in
the four following years 981 died--668 at home, in the asylums 313. If
we assume that there died at home as many in 1856 as in 1857, viz.,
230, then the number of deaths at home during the quinquennium would
have amounted to 898, and the whole mortality, adding the 313 who
died in the asylums, would have been 1,211--only 109 more than the
new cases. But one must not so reckon. There died, especially in the
early days, a much larger proportion in the asylums than outside; and
it is evident, secondly, when one observes the figures in a district
from which at the commencement only very few cases were sent to the
asylum, that the new cases are much more numerous than the deaths. In
Nordmoere, for example, the number of new cases from 1856-60, was 81;
that of deaths, 46; only 14 were sent to the asylums, and the disease
increased during the quinquennium, the cases rising from 105 to 119.
One finds the same thing in Soendmoere--new cases 104, deaths 42, sent
to asylums 28; number of cases in 1856, 178; in 1860, 195. In these
two districts, then, the disease was evidently on the increase, and
this would probably have been the case throughout the country, had
many cases not been removed from their homes to the asylums; as, for
example, in Soendfjord. Here there were, in 1856-60, 214 new cases,
116 deaths, 211 sent to the asylums; number of cases 1856, 431; 1860,
306. If we examine in this way the numbers in the different districts,
we find everywhere that decrease of the disease depends on the numbers
isolated in the asylums. Where isolation was insufficient or absent,
there was no decrease, but either the numbers increased or remained
stationary; where, on the contrary, isolation was thorough, the
decrease was invariable. This can only be explained in one way, viz.,
that isolation is the cause of the decrease, and isolation can only
have effected improvement by removing from the homes of the people the
sources of infection. Further, during the next five years, the number
of new cases in those districts where isolation was good continued to
sink; where there was none, or it was insufficient, the numbers either
rose or remained almost stationary. We will once more compare Nordmoere
with Soendfjord. In Nordmoere, in 1856-60, 81 new cases, 14 sent to the
asylum; 1861-65, 88 new cases. In Soendfjord, 1856-60, 214 new cases,
211 sent into asylums; 1861-65, 146 new cases.
We consider it superfluous to point out further how the isolation
of the patients has caused the decrease of Leprosy in Norway. It is
not possible to explain the action of isolation by the elimination
of heredity; the time is too short for that. The only one possible
solution is that which we have given, and therefore we regard this
decrease of Leprosy in Norway following on isolation as the best proof
of the contagiousness of Leprosy. Leprosy is, then, according to our
view, a contagious disease, and only contagious, not hereditary.
How Leprosy is “caught,” we do not know, but we think it is probably
by inoculation; and the nodular form must be more dangerous than the
maculo-anæsthetic. This last statement seems to be confirmed by the
fact, that in Sogn, where 56.6 per cent. of the cases are nodular and
43.4 per cent. maculo-anæsthetic, the increase varies between 8. and
10.8 per cent., while in Soendfjord, with 72.6 per cent. nodular, and
27.4 per cent. maculo-anæsthetic, it is between 14.4 per cent. and
19.5 per cent. In the nodular form there are incomparably more bacilli
than in the maculo-anæsthetic, and in the latter there is no discharge
containing bacilli, which in the former is almost always present. It
is not improbable that Leprosy may be conveyed by the clothes. We know
of one case in which a young man became affected one year after he
had worn a pair of old drawers given him by a leper. The same thing
happened to another young man who wore several pairs of his leprous
father’s stockings.
Although we are not acquainted with the spores of the Lepra bacillus,
it is quite conceivable that the bacilli are spore bearing.
Unfortunately, we know of no method of determining whether the bacilli
are alive or dead, and therefore Arning’s observation of the bacilli in
the fæces does not decide the question as to whether the bacilli can
live for any time outside the body, even admitting that the bacilli
which Arning found were actually Lepra bacilli.
After completing this work I received “The Recrudescence of Leprosy
and its Causation,” by William Tebb. The author seeks to prove that
leprosy is everywhere on the increase as the result of the introduction
of vaccination. The book as a whole is directed against vaccination
as dangerous. Distinct proofs for his contention that leprosy may be
conveyed by vaccination from arm to arm, the author, to our thinking,
does not supply. Since Dr. Arning found lepra-bacilli in the contents
of vaccine vesicles in lepers, the possibility of the communication in
this way can scarcely be denied. But that it can be frequent, I cannot
possibly believe. In Norway, vaccination has been compulsory during
all those years in which leprosy has steadily diminished. In 1891 I
put the question to all those doctors in Norway who had anything to do
with leprosy, whether they had ever met in their practice with a case
which could be ascribed to vaccination. Not a single one had observed
such a case. And yet, here in Norway, lymph must often be taken from
the children of leprous families. But since leprosy is very rare in
children, it is evident that leprosy cannot be conveyed in this way.
That vaccine vesicles in the non-leprous members of leprous families
contain lepra-bacilli is incredible.