26
THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY. [VII, I
On the other hand, the thermal symptoms observed in these animals were usually
of a remittent type, although in a few instances the temperature continued to
remain high and even went up to 107°F. The condition in the Kirkee outbreak was,
to all appearances, a chronic form of theileriasis, as is evidenced by the history
of some of the animals. Thus, in one instance, the disease, after running an
indifferent course, with periods of prolonged absence of any clinical symptom,
suddenly assumed an acute form and progressed to a fatal issue after lasting for
only one or two days. The examination of blood smears from the affected animals,
however, showed, as a rule, the presence of only rare Theileria parasites and Koch's
bodies, but in one instance the blood smears showed numerous parasites in the
acute stage of the disease, about 50 per cent of the red blood-corpuscles being
invaded, although the anaemic changes were almost negligible. It is worthy of
note that in the Kirkee outbreak death occurred in only three out of a batch of
ten affected bulls (30 per cent), so that this relatively low mortality rate presents a
striking parallel to what was found to be the case in the Lahore outbreak,
BLOOD PICTURE
As already mentioned, the parasites make their appearance within the first
few (usually one to three) days of the first rise of body temperature, although at
this time they occur in extremely small numbers, not more than one parasite being
seen in any one corpuscle. As the disease, however, advances, they rapidly in-
crease in number and may eventually invade 50 to 100 per cent of the red blood-
corpuscles, as many as ten parasites having been seen in a single corpuscle. In
regard to Koch's bodies, these usually vary in number from " rare " to " numer¬
ous ", a maximum of ten having been seen in a single field. Both forms (gamonts
and agamonts) have been observed and it is also not unusual to encounter occasional
examples of " split up " forms. Koch's bodies have also been encountered in
preparations made from the internal organs, e.g., lymphatic glands, spleen, liver,
lungs, kidneys, testicles and even from lesions in the stomach.
The Theileria parasites are usually seen as round or slightly oval forms, having
the appearance of signet rings (Plate VII), and they are mostly uniform in size,
measuring from one to two microns in diameter. The chromatin, particularly
that at the peripheral portion of the parasite, takes the stain well, two chromatin
spots being sometimes connected together, but the cytoplasm, which takes a pale
blue colour when stained with Giemsa's or Leishman's stain, can only be seen in
outline. It is extremely rare to encounter the rod forms of the parasite, and
when they are present they presumably represent the " carrier " forms of T.
mutans, inasmuch as the latter are commonly met with even in the incubative
stage of the disease.
It is of interest that Babesia bigemina, in " rare " to " very large " numbers,
was observable in more than 60 per cent of the bulls that reacted to artificial
infection with theileriasis, both during the period of incubation and in the early