IS LEPROSY A TELLURIC DISEASE ? 
779 
contagious in its specific products,” and “ contagious not only directly, 
but also indirectly, by articles which serve to carry the bacilli and their 
spores. * * * § 
That, evidently, is a just criticism ; for what is required is proof 
that leprosy actually is directly or indirectly conveyed, and not merely 
an inference from analogy that it ought to be, or must be, so conveyed. 
But no sufficient experimental proof of Dr. Neisser’s assumption 
ever has been given, f 
In this discovery of the B. lepra , then, and of its causative con- 
nection with lepriasis, we ought not to see a proof that leprosy is 
communicable by lepers; we should see in it only the proof that 
leprosy must be classed among the infective processes. J All the 
infective diseases are not maintained by communication with the sick, 
it will be remembered. Thus, tetanus is an infective disease; yet, 
as a matter of practice and of fact, tetanus is not maintained by com- 
munication between those suffering from it and the healthy. 
Now, as to the direct communicability of lepra, probably no 
important difference of opinion longer exists. Probably no one of 
great weight would roundly deny that leprosy may, perhaps, be directly 
communicable from the sick to the healthy. We have, I think, no 
proof of it, but that is not a sufficient reason for denying it; and, 
indeed, there is one ease§ — though, as far as I know, one only — in which 
direct communication seems to have occurred: one only, I mean, in 
which the circumstances seem to have been observed and recorded with 
accuracy, and in which all causes but direct communication seem to 
have been excluded by them. On the other hand, I scarcely think 
that anyone of very great weight would at this day assert that leprosy 
was maintained by direct communication, in the face of well -ascertained 
epidemiological facts concerning this disease the world over. Here, 
again, we have not to go outside Australia in order to perceive that as a 
matter of fact leprosy cannot be directly communicated, except very 
rarely indeed at most* 1 know of only three cases out of many in whites 
(among whom alone the details can be accurately learned) in which 
known direct communication with a leper could have operated to cause 
the second case ; and those instances are on all-four** with the 
examples usually cited in support of direct communicability, and, like 
them, are liable to criticism of damaging kinds. On the other haud, 
though we imprison our lepers rigorously as soon as we discover them, 
generally we do not discover them until they have been at large for 
several years ; and yet fresh cases do not usually occur in the house- 
hold in which they lived, and which was certainly thus exposed for 
long to whatever risk attaches to free communication with the sick, 
hut by far most ofteu in fresh households altogether. 
That Australian experience is far from being exceptional. Every- 
one is familiar with the fact that lepers who have contracted their 
* It should be noted that Dr. Neisser expressed this opinion nearly fifteen years 
ago. I do not know whether he has more recently confirmed it ; if not, ft is, of course, 
possible he might now modify or explain it. (Sec Virchow’s Arehiv, 1881.) 
+ Centralblatt fiir Bacteriologie und Parasitenkunde, 1893, vol. xiii. — Dr. Max 
Wolters. 
X Report of the Leprosy Commission in India. 
§ Dr. Hawtrey Benson’s Dublin Journal of Medical Science, 1877. Professor 
H. Leloir also seems to regard the evidential value of this case as unique. (Traite de 
la Lepre, p. 309.) 
