2
Para, 2
respect. Personally, I should have preferred to postpone the study of kala-azar
until the general laws of infection by malaria were, if possible, ascertained by a
completion of the study of proteosoma, which offers peculiar facilities for the
purpose ; but owing to the gravity of the epidemic in Assam, and to the fact
that the nature of it was still being contested in the professional press, I thought
that I might be expected to make some study of it at this point, even at the
the cost of interrupting the logical course of the research. Accordingly, after
spending a few weeks in the Darjéeling District on the examination of a disease
called kala-dukh or kala-jwar, which is prevalent there, 1 went to Assam.
I arrived at Gauhati, Assam, on the 11th September, and proceeded at once
to Nowgong, where, I had been told by the Sanitary Commissioner of the
Province, numerous cases of kala-azar were to be found. I remained in the
Nowgong District, chiefly in Nowgong itself, for six weeks ; during which I
took the statements of four medical officers of the district with regard to the
disease ; satisfied myself as to its identity ; examined its pathology ; and com-
pared it with other sickness in the locality. At the end of that period, being
of opinion that nothing was to be gained by a further study at that season
of sumcient importance to delay any longer the pressing work on the general
theory of malaria which remained to be done in the short time left to me, I
requested permission to return to Calcutta. The permission was granted ; and I
was directed at the same time to submit my report on kala-azar as soon as
possible.
It will be perceived that a complete study of the whole subject was scarcely
possible in so brief a period. Fortunately the copious literature already in
existence has previously dealt with many details, and I was able to concentrate
attention on a few important questions, namely, those which had been left
indeterminate at the time. In effect it will be seen the work has practically
limited itself to a study of the nature of the disease ; the epidemiology must be
left untreated for the present as being an incident in a wider investigation.
2. Analysis of Existing Literature.—The literature on kala-azar,
already voluminous, is to be found chiefly in the Annual Sanitary Reports of
Assam from 1882 onward ; in two special reports [ 3 and 4 ] written by Major
Giles and Captain Rogers, both of the Indian Medical Service, as a result of a
year's investigation made by each; in a controversy on the subject in the
medical press [ 5, 6, 7, 8, 9, 10, 11, 12, 13 ] ; and in Manson's Tropical Diseases
[14].
In considering this literature briefly I propose first to refer to those points
on which there is pretty general agreement.
The high death-rate of the disease is established by very numerous reports
and statistics.
There is no doubt that it is an epidemic disease ; this is certain from its
progress up the Brahmaputra valley. Though it appears to have existed for
many years in the Garo Hills, it was not officially noticed until 1882, when an
investigation by Mr. McNaught, then Civil Surgeon of Tura in the Garo Hills, is
recorded in the Sanitary Report. After this date the disease was observed to
spread slowly up the valley, through the Goalpara, Kamrup, and Gauhati dis-
tricts, abandoning each in turn, up to the Nowgong District, which it reached
in 1889, and where it is now present. It has also spread to the Tezpur and
Mangaldai districts. Further details of this progress will be found in Roger's
Report [ 4 ]. The facts on this point, based as they are on numerous official
reports and on the experiences of many district officers, medical and civil, are,
I think, incontestable.
While the capacity of kala-azar for spreading from point to point has
never been called in question, the opinion seems to have prevailed at first that
its extension is due, not to direct communicability from the sick to the
healthy, but rather to the progression of certain climatic (?) conditions
favourable to its existence ; see for example Dobson's opinion that it is not
contagious, quoted by Rogers [ 4, p. 4 ] ; see also [ 4, p. 5 ]. Later, however,
when it was seen how frequently isolated villages, or the inmates of one house,
or members of one family living in different houses, became infected, while
neighbouring villages, houses and families escaped, it became impossible to deny
the communicability of the disease. The fact is accepted both by Giles [3, p. 27]
and by Rogers [4, p. 164] ; also by the medical officers, whose statements are