7
The effect of different doses of atoxyl in equines, the subject of
spontaneous equine trypanosomiasis.
26, A single dose of atoxyl (1 to 2 grammes) when injected subcutaneously
is capable of temporarily destroying (for 4 to 5 days) the mature trypano-
somata, when present in considerable numbers in the circulation of an equine.
In order to totally destroy the immature forms of the flagellate, it is necessary
to administer repeated doses of the drug 3 to 5 grammes on each occasion, at
intervals of eight to ten days, according to the body-weight of the affected
animal.
It must, however, be borne in mind, that equines the subjects of trypano-
somiasis, especially when large numbers of flagellates are present in their blood,
are much less tolerant of atoxyl than healthy animals, as was found to be the
case with Arsenic in the form of Liq. arsenicalis.
27. Are Indian elephants susceptible to inoculated equine trypanoso-
miasis ?—The evidence is fairly conclusive, viz.:—that old Indian elephants in
health, are either insusceptible or only very slightly susceptible (maximum
one flagellate in twenty fields of the microscope) to equine trypanosomiasis,
even when the virluent material is injected subcutaneously in the comparative-
ly large doses of 20 to 500 c.c. of blood containing the T. evansi in numbers.
28. Is the casual agent of equine and camel trypanosomiasis, one and
the same, viz., the T. evansi ?—As laid down by Laveran and Mesnil, the
general opinion was primarily, that surra and nagana were two names for
one and the same malady. They carried out experiments in order to solve
the question, as to whether an animal protected against "nagana" could be
injected by inoculation of surra material. The result of these experiments
was that animals succumbed to surra, thus proving that the T. evansi and
T. brucei are two species of flagellates quite distinct. If the experiments
above referred to, on two goats and one buck, were sufficient to differentiate
T. evansi from T. brucei, then the results of experiments with the animals
now to be recorded, would tend to prove that the causal factor of camel try-
panosomiasis is not one and the same species as that of equine trypanoso-
miasis (T. evansi).
I. A camel aged eight years, contracted trypanosomiasis spontaneously,
in June 1901, and was kept under close observation, until death which
occurred in September 1905. In February 1905, as the flagellates had been
absent from the blood for several months, a pony was inoculated subcutaneously
with 20 c. c. blood from the jugular vein of the camel. The pony, however
subsequently, showed no rise in temperature or sign of the disease, although
when inoculated at a later date with blood containing T. evansi contracted
the disease and succumbed. Therefore, in February 1905, the blood of the
camel did not contain the causal agent in the mature or immature form. In
June 1905, during the season when the Tabanus was present in great numbers
at an elevation of 7,750 feet, the camel was placed in a shed with a second
camel which had been inoculated with spontaneous equine trypanosomiasis
(numerous flagellates in the blood).
The animal, the subject of Tibersa, contracted the equine form of disease,
incubation period about ten days and succumbed in sixty-two days.
II. A country-bred entire donkey, aged two years, was inoculated sub-
cutaneously on 29th May 1905 with 0.2 c.c. of blood drawn from the jugular
vein of a camel, the subject of spontaneous trypanosomiasis, trypanosomata
swarming.
The period of incubation lasted 4.5 days.
Nineteen paroxysms occupied 93 days, and nineteen intermissions 334 or
a total of 427 days. As on August 4th 1906, the blood of the donkey was
incapable of conveying the disease on inoculation of susceptible animals, it
was re-inoculated, but on this occasion with 1.0 c.c. of blood from a case of
spontaneous equine trypanosomiasis. The period of incubation lasted 5.5 days.
Seven paroxysms and seven intermissions occurred occupying 30 and 37 days,
respectively, death taking place on the 15th October 1906.
The course of the disease occupied 67 days.
III. A donkey mare, aged five years, was subcutaneously inoculated on
18th February 1905 with 20 c.c. of blood direct from the jugular vein of
a camel, the subject of spontaneous trypanosomiasis. The blood contained