444 
CONGRESS ON TUBERCULOSIS. 
international measures, because hydrophobia, which can be 
very easily and rapidly suppressed, is always introduced again 
year after year from the neighboring countries. 
Permit me to mention only one other disease, because it is 
etiologically very closely akin to tuberculosis, and we can learn 
not a little for the furtherance of our aims from its successful 
combating. I mean leprosv. It is caused by a parasite which 
greatly resembles the tubercle-bacillus. Just like tuberculosis, 
it does not break out till long after infection, and its course is 
almost slower. It is transmitted only from person to person, 
but only when they come into close contact, as in small dwell¬ 
ings and bedrooms. In this disease, accordingly, immediate 
transmission plays the main part; transmission by animals, 
water, or the like is out of the question. The combative meas¬ 
ures, accordingly, must be directed against this close intercourse 
between the sick and the healthy. The only way to prevent 
this intercourse is to isolate the patients. This was most rigor¬ 
ously done in the Middle Ages by means of numerous leper- 
houses, and the consequence was that leprosy, which had spread 
to an alarming extent, was completely stamped out in Central 
Europe. The same method has been adopted quite recently in 
Norway, where the segregation of lepers has been ordered by a 
special law. But it is ‘'extremely interesting to see how this 
law is carried out. It has been found that it is not at all neces- 
sary to execute it strictly, for the segregation of only the worst 
cases, and even of only a part of these, sufficed to produce a 
diminution of leprosy. Only so many infectious cases had to 
be sent to the leper-houses that the number of fresh cases kept 
regularly diminishing from year to year. Consequently the 
stamping-out of the disease has lasted much longer than it 
would have lasted if every leper had been inexorably consigned 
to a leper-house, as in the Middle Ages ; but in this way, too, 
the same purpose is gained, slowly indeed, but without any 
harshness. 
These examples may suffice to show w 7 hat I am driving at, 
which is to point out that, in combating pest'lences, we must 
strike at the root of the evil, and must not squander force in 
subordinate ineffective measures. Now the question is whether 
what has hitherto been done, and what is about to be done 
against tuberculosis really strikes at the root of tuberculosis, so 
that it must sooner or later die. 
In order to answer this question it is necessary first and 
foremost to inquire how infection takes place in tuberculosis. 
