68
Para. 39
VI.—Conclusions.
39. The Nature of Kala-Azar.—It will be advisable, before attempting
to draw final conclusions, to separate the facts from the theories in the previous
discussions. The facts appear to me to be as follows :—
1. Kala-azar is an epidemic and communicable disease (paragraph 35).
2. Its symptoms are very like those of malarial fever. In established,
i.e., fairly advanced, cases, the disease consists principally of considerable
enlargement of the spleen and liver, accompanied generally by a low fever, a
certain degree of anæmia, and other secondary symptoms. The history of such
cases is always that the illness commenced with high fever, generally with
repeated rigors ; and that the organs began to enlarge after this fever had lasted
some time (paragraph 6).
3. The death-rate is high ; but recovery often occurs.
4. The disease is known to exist only in malarious localities.
5. In Nowgong, side by side with the cases of established kala-azar, there
were numerous cases of typical early malarial fever, in which the malarial
parasites were found in abundance, and which already showed commencing and
rapidly increasing enlargement of the liver and spleen. There were also cases of
a later stage of malarial fever, in which the organs were more enlarged and
a few parasites were found ; or in some of which, if no parasites could be
detected, melanin could be obtained from the spleen (paragraph 18).
6. In cases of established kala-azar at Nowgong, the parasites of malaria
were found in a few of the more recent ones, and melanin alone in the organs
of a few more ; but in many, including some autopsies, no parasites and no
melanin at all could be detected. In most of the last, both enlargement of the
organs and low fever were present. Yellow pigment was found in a large
number of the cases (paragraph 18).
7. Kelsch and Kiener state that melanin is often absent in cases which
they describe as malarial fever, a few months after the beginning of the illness.
Daniels states that in British Guiana the majority of enlarged spleens contain
no melanin. Vandyke Carter, and Kelsch and Kiener describe a secondary
fever, not due to the parasites, connected with malarial fever ; and Daniel notes
the existence of a similar fever in cases of enlarged spleen, even in cases when
the enlarged spleen contained no melanin (paragraphs 26 and 27).
8. There is no evidence to show that melanin always remains permanently
in the organs.
9. In seven autopsies on cases of established kala-azar, no difference could
be detected between the cellular structure of the organs of cases in which
melanin was absent and that of cases in which it was present. Fatty degenera-
tion was generally absent (paragraph 18).
10. No evidence was obtained by me of kala-azar being due to any cause
other than malaria (paragraph 18).
11. Ankylostomes were found in a considerable number of the cases of
kala-azar examined by me (paragraph 18).
12. Ankylostomes do not produce enlargement of the liver and spleen
(paragraph 11).
13. Numerous epidemics of a disease thought to be malarial fever are on
record (paragraph 36).
14. One of the malarial parasites of birds, proteosoma, is communicable
from sick to healthy birds by the agency of the mosquito (paragraph 37).
15. The mosquito stage of one of the parasites of human malaria has been
partially followed (paragraph 37).
These facts drive us at once to the following alternative :—
(a) Kala-azar is not malarial fever; but a disease macroscopic ally and
microscopically similar, except for the absence of the parasites and
melanin. If so, this disease exists also in British Guiana, and pos-
sibly in other localities ; but only in localities where typical malarial
fever abounds as well.
(b) It is malarial fever ; in most cases of which the parasites disappear
toward the later stages of the disease, and in a few cases of which
the melanin also disappears at a still later period, leaving the