5
even if concurrently made, can have had little
or no influence on the progress of the disease.
And further, were hygiene (in the ordinary sense
of the word) really so operative as is urged the
isolation of lepers must offer scanty promise of
good, as not itself materially lessening hurtful
conditions ; but this inference is contrary to
other reasonable deductions. Some of the above
remarks apply to hereditary influence, as a
source of leprous infection ; for in not a few ex-
amples of local decline of disease submitted to
analysis there has been found too prompt and
decided an amelioration in families to permit
of this slow-acting agency being regarded as
mainly influential. And in sum, so far as
appears to me, leprosis can be directly mitigated
by dietetic, hygienic or climatic influences only
to the same extent as, and no further than, the
analogous chronic infections of man, known as
syphilis and tuberculosis.
Lastly, failing other explanation, it may be
asked if the decline of leprosy in Norway be not
nearly connected with the practice of isolating
the sick in the Asylums erected for their use.
These institutions, I would remark, were origi-
nally intended, by segregating apart the more
vigorous lepers of both sexes, to aid in checking
the propagation of disease through marriage ;
they were also meant to accommodate the worst
cases, or those a burden to their friends ', and to a
minor extent they were to serve as hospitals for
curative treatment. Though founded so far back
as 1856, it has only of late become possible to
estimate their influence over the general progress
of this very chronic pest ; and owing to the
inevitable obstacles to correct registration alluded
to in Part I., the data suitable for satisfactory
analysis are still but limited. Dr. Hansen's
observations in his quinquennial Reports for 1875
and 1880 may, I think, be regarded as the earliest
attempts scientifically made to determine the real
effect of the isolation of lepers in a community :
his main conclusions are summarized below. I
have also considered the recorded opinion of
preceding Norse physicians ; and, on the whole,
prefer the later view. In Part I. it is shown that
leprosy is not declining simply by a process of
dying out, but that there is continually taking
place a certain reproduction of disease ; and it is
only when and where this last proceeds at a lesser
rate than the death-loss that the pest can be said
to be subsiding. A third condition, however,
concurs ; viz., a contemporary removal from the
districts and isolation in Asylums of many old
and new cases of infection ; and the question now
arises, how does this isolating process influence
the others ? or these failing, itself account for the
amendment proved in Part I. ? Within the
Asylums there occurs a higher death-rate than
outside, whilst in them no new cases can arise ;
on the other hand, in the country districts there
obtains a lower death-rate, and here alone do
new cases appear. The Asylums serve as a means
of partially evacuating the infected districts,
abstracting particularly the worst examples of
disease ; and they are not necessarily, it might be
said, otherwise concerned in the general progress
of disease. But would such assertion be correct ?
Let it be agreed that to clearly comprehend the
course of leprosy, attention must be directed to
conditions obtaining in the districts ; amongst
which the chief one is the number of " new"
cases which arise, proportionately to the total of
"home-dwelling " sick : for if the accretion-rate
of new cases exceed the death-rate of home-dwel-
lers, then disease is on the increase ; and vice
versâ. Now, in his report for 1875, Dr. Hansen
shows that up to 1,870, in only one easterly
district had the death-rate exceeded the produc-
tion-rate ; whilst everywhere else the accretion-
rate was highest. There had everywhere been
removals to the Asylums, and hence a diminution
of the mortality outside these institutions : still,
had no such emptying of the districts taken
place the death-rate would nowhere, with the
exception named (itself doubtless open to expla-
nation), have exceeded the production-rate, and
the total of lepers in the districts at the close of
1870 would in all probability have been quite
as great as in 1856—or "in some places un-
questionably greater." Elaborate tables are
given, from which it appears that the yearly
increment of new cases in a district regularly
declines just according to the larger number of
lepers removed to the Asylums. Thus, e. g., in
Sogn-district, whilst these increments proportion-
ately to the numbers living at home remain the
same in 1856-60, 1861-65, and 1866-70, yet by
removal to Asylums, the numbers at home being
continuously reduced, there has occurred a con-
comitant reduction of new cases, as shown in the
successive yearly sums of 89, 64 and 59 ; which
still display a definite and fixed ratio to the
immediately preceding totals of home-dwellers.
No exception to the above rule has been found ;
and from close and rigid scrutiny of the data
alone, it seems clear that the diminution of new
cases in the districts goes, pari passu, with the
lessening number of home-dwelling sick : at least,
amongst all the several data, no other relationship
is so clear and invariable as this one.
In his Report for 1880, with matured statistics
coming down to 1875, Dr. Hansen is not less em-
phatic ; and finding a determinate ratio between
the number of new cases, and the immediately
preceding number of home-dwelling lepers in a
district (taking 5-yearly periods for each), he
employs such ratio to make a forecast of the
future progress of leprosy in Norway. The parti-
cular data adduced in support of these views are
certainly remarkable and seem to me adequate ;
they are, however, too elaborate for reproduction
here.* Once more, it is shown that in Norway
the proportionate growth of leprosy is by
no means diminishing; and hence an inference
that the conditions for extension of the disease, are
in no way more unfavourable now than formerly.
Since, therefore, the total of lepers is certainly
lessening, this cannot be due to amendment (if
* Dr. Hansen's figures refer to separate districts in the
total affected area. On analysis of column 3 (new cases) and
column 7 (lepers at large) of the large table above, embracing
the whole area, I find, after excluding the incomplete data of
later years, that during the earlier years 1856-70 inclusive,
the annual ratio between new cases and sick home-dwellers is,
in the main, very near 1 to 10. This implies the yearly
advent of 1 new case to every 10 lepers at large ; which is a
ratio larger than the mean death-rate of such lepers. Precise
figures for the three included quinquennial periods, are
succesively as follows:—Mean annual number of lepers at large
2,371, of new cases 239; 1,994 and 204; 1,859 and 177.
Subsequently to 1870, the ratio of new cases gradually
declines ; doubtless because their numbers have not yet been
sufficiently ascertained. These data might have been intro-
duced into the text of Part I., but they were reserved for
this place as confirming the inference of Dr. Hansen, who
does not however (that I see) state his estimate to be the
same as that here independently elicited. Whilst well aware
that several conditions must intervene, I am still of opinion
that here is evidence of a quite definite influence ; and I agree
with Dr. Hansen that the Norwegian statistics contain no
more constant datum than this one, of a distinct proportion
between lepers at large and the newly-made leprous,
B 1111—2