MUKTESAR, FOR THE YEAR ENDING THE 31ST MARCH, 1933.
29
treatment of this condition, it does not seem necessary to replace this
with any of the newer drugs for the treatment of Redwater, unless it
can be conclusively shown that such a course would be justified, at any
rate, on grounds of economy, if not of efficacy.
(2) Theileriasis of Cattle.— During the year under report, the Sec-
tion has carried out an extensive series of observations upon a virulent
form of this disease affecting hill bulls at Muktesar. The original
strain of the " virus " was isolated from a fatal case of natural theile-
riasis at Muktesar and the strain has now been kept alive for a period
of 9 months by passaging through susceptible hill bulls, the total
number of animals utilized for this purpose up to the end of the year
being 92, out of which 42 (45.6 per cent.) proved refractory to the
infection, whilst in the case of the remaining 50 animals (54.4 per cent.)
the disease was successfully reproduced. The condition has been
studied from a number of different points of view and a full report
upon the findings will appear in due course. It is only necessary
to allude here to the main points that emerged in the course of this
investigation :—
(a) Identity of the Parasite.—Of the four well-known species of
cattle Theileria (T. parva, T. dispar, T. annulata and T. mutans), T.
annulata would appear to possess the closest affinity to the parasite in
question, but the two differ in certain essential characteristics, the most
noticeable of which are (i) the decidedly lower mortality rate with T.
annulata (5-20 per cent.), as against the mortality rate of 82 per cent.
obtained with the Muktesar parasite; (ii) the somewhat lesser per-
centage of round forms in T. annulata infections (70-80 per cent.) than
is the case in infections with the Muktesar parasite (80-90 per cent.).
(b) Pathogenicity.—In artificial infections, the disease has an
average incubation period of 16 days, and death usually ensues after
the disease has run a course of 3 to 11 days, the most characteristic
symptoms being fever, lachrymation, enlargement of the superficial
glands, inappetence and diarrhœa, with blood-stained fæces in a large
proportion of cases. In acute cases, 50-60 per cent. of the red blood
corpuscles may be invaded by the parasites and as many as 10 parasites
have been observed in a single corpuscle, whilst the Koch bodies, the
presence of which constitutes an invariable feature of the disease, may
make their appearance in the blood quite early in the infection. The
infectivity of emulsions of the following organs from dead animals was
tested upon healthy cattle with positive results:—lymphatic glands,
spleen, lungs, liver and kidney. An attempt was made to reproduce
the disease in two buffaloes by the inoculation of blood derived from
an acute case of theileriasis, but the results were negative.
(c) Viability.—In response to a request from Mr. R. Daubney,
Chief Veterinary Research Officer, Kabete, Kenya Colony (East Africa),
for a strain of these parasites, a series of preliminary experiments was
carried out upon the viability of the " virus " when kept under sterile
precautions in the refrigerator. It was found that when stored under
such conditions the "virus" completely lost its infectivity within 6
days.
D 2