62
Paras. 33-35
The next objections (2) have been discussed at great length. Evidence
from Kelsch and Kiener and Daniels was given to show that the melanin (and
consequently the parasites) may disappear early, and that the condition of
enlarged organs without melanin exists in other countries besides Assam ; and
citations were made from these writers and from Vandyke Carter to shew that a
secondary fever may exist in connection with this condition (paragraphs 26 and
27). An attempt was then made to explain these phenomena from the point of
view that they may originate in a malarial infection (paragraphs 28-32) ; and it
was finally shown (paragraph 32) that the only pathological argument which
remains against the malarial theory of kala-azar is one based on the supposition
that melanin can never be eliminated except after several years.
In the absence of any definite proof or this and in the existence of some
evidence to the contrary, I think that this argument, too, may be set aside.
The last objection (3) is an epidemiological one, and remains to be
considered.
V.—The Epidemiological Difficulties Discussed.
34. Definitions.—It is generally thought that malarial fever is due to
a poison generated in the soil, air, or water of certain localities, which are
thence termed malarious localities. It is generally thought, moreover, that the
disease is not communicable, directly or indirectly, from the sick to the healthy.
On the other hand, kala-azar is not connected with any one locality, and
it is communicable from the sick to the healthy.
Hence, it is said, kala-azar cannot be malarial fever.
Let us examine the question.
I have admitted in paragraph 2 that kala-azar is an epidemic, and that
it is "communicable from the sick to the healthy in some unknown manner."
Let us first endeavour to define these ternis more exactly.
A disease is said to be epidemic when it appears suddenly in a locality.
Now, since diseases are not known to originate ab initio anywhere, this implies
that the epidemic disease has spread into the locality from without—that it is a
spreading disease. But it implies no theory as to the mode of spreading.
It is possible that a disease may spread in many ways : by the extension
of some meteorological influence favourable to it; by the spread of some
morbific element in the soil, air, water, flora or fauna of a country, from which
it is communicated to man ; or by communication, direct or indirect, from
man to man.
In saying, then, that kala-azar is both epidemic and communicable, we
state not only that it is a disease which is capable of spreading, but that we
know at least one way in which it spreads—that of communication from the
sick to the healthy. It will be advisable, first, to recall the evidence on which
these statements were made, in order to be quite sue of their truth.
35. Evidence regarding the Epidemicity and Communicability of
Kala-Azar Recalled.—The proof that kala-azar is a spreading disease is, I
consider, quite sufficient, namely, that it has actually spread up the Brahma-
putra Valley from the Garo Hills to the Nowgong District and beyond ; the
fact is attested by official statistics and by the statements of everyone who
knows the locality. No discussion on this point is possible.
The other point is, perhaps, not quite so clear. As Sir W. R. Kinsey said at
the discussion of the subject before the Royal Medical and Chirurgical Society
[11, p. 820], it is difficult to prove the communicability of diseases that
simultaneously affect a number of people.
It is proved in this case, however, by the facts, everywhere recognised, that
kala-azar tends to confine itself to isolated villages, families and houses, and
that it has frequently appeared in such after the entry of an affected person.
Had the disease spread by the extension of some meteorological condition
it would have broken out everywhere at once ; had it spread by means of some
morbific influence slowly extending itself in the elements of external nature,
it would not have moved by families and affected persons. If we accept the
universal experience on the subject, which I think we are bound to do, we
must also accept that the disease is a communicable one.