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Scientific Memoirs by
I have personally examined were undoubtedly instances of helminthiasis, and,
whatever may be called " Surra " elsewhere, that these animals died from the
action of nematode parasites, and from no other cause, is a matter which admits
of not the slightest doubt; and it is equally certain, whatever may be the
correct vernacular name of the disease, that such cases are a source of very
heavy mortality in Assam ; and I have collected some information tending to
show that the same is the case in Burma.
As will be seen in the sequel, the disease is one which can hardly spread
to any great extent in a dry climate ; but, as it is by no means unknown in
Europe, a tropical temperature is by no means essential. Most of the animals
I have examined were perfect museums of parasites; but, of the various species
found, only two 1 can be considered as effective in producing the mortality, and
these are two strongyloid mematodes, closely allied to each other and to the
well known Dochmius duodenalis found in the human subject, which latter
parasite has of late been causing a terrible mortality among human beings in
Assam, and the life-history of which it has lately been my special business to
investigate. These two parasites are Sclerostomum tetracanthum Diesing and
S. equinum (Rudolphi), and, though the latter not unfrequently determines the
sudden death of animals, it is more especially the former which is the efficient
agent in the present epizootic, and it is its life-history only that it is proposed to
discuss in the present paper. In it I have preferred to adhere to the generic
name Sclerostomum, as the worm agrees in all its characters with the definition
of the genus, and I can see no advantage in forcing it into the already unwieldy
genus Strongylus.
The first case that was brought to my notice was that of an officer's
charger, which was sent to me by Dr. Hall as a case of " Surra," and, knowing
the interest I take in epidemic disease, he believed would interest me. I was at.
once struck with the extraordinary resemblance which the case presented to one
of anchylostomiasis in the human subject. There was the same weakness and
wasting, and the same characteristic deadly pallor of the mucous membranes;
indeed, the similarity was so striking that I at once proceeded to examine the
dung microscopically: nor was my astonishment diminished when I found that
it contained countless numbers of ova, absolutely identical in general appearance
with those of Dochmius duodenalis. A reference to the micrometer, indeed,
showed them to be considerably larger than the ova of the latter ; but, in all
other points, the resemblance is so close that it would be quite impossible to
distinguish them by any other test than measurement. Shortly after, the
animal's recovery being obviously hopeless, its destruction was decided
upon by a board of survey, and I obtained the opportunity I had been hoping
1 I have si nce found t hat , under t he name of S.e q u i n u m ,
I i n c l u d e d t w o c l o s e l y a l l i e d s p e c i e s , S .e
q u i
nun , and another, which appears to be new to science, and which I describe in a note, following the presen
paper, under the name of S. robustum, sp. n. Hence three species were concerned in the mortality.