cclxxix
SUBCUTANEOUS INJECTION OF GUINEA-PIGS WITH BLOOD DRAWN FROM
A BULL INOCULATED, AND AT A LATER DATE RE-INOCULATED WITH
SURRA.
As is before noted, the loss of virulence—on introduction of the hæmatozoon into the
bovine species—points to the fact that there may be a possibility of producing some form of
immunity in other species of animals, by the introduction either subcutaneously or by intra-
venous injection of the blood itself or of the proteid material obtained from the blood of
bovines some time after their inoculation with Surra.
With this end in view a series of experiments were undertaken with the object of
ascertaining—
(I) Whether the further progress of the disease could be checked in Guinea-pigs
—in the blood of which hæmatozoa were present—by the subcutaneous injection of small
quantities of fresh bovine blood at intervals of a few days. The bull from which the
blood was to be taken having been inoculated and at a later date reinoculated with Surra.
Experiment (i).—Guinea-pig inoculated with 0.25 c.c. of blood on the 12th November
1892, taken from the Jugular Vein of Horse No. LXXIII. The hæmatozoon made its appear-
ance in the blood 12 days later on 24th November 1892. On December 5th, 8th, 13th and
15th, respectively, the animal received subcutaneously 1.0 c. c. of blood drawn from Bull No. I
(inoculated with Surra on 24th March 1891 and re-inoculated after an interval of 17 months
on 22nd August 1892). Death took place on the 25th February 1893, one hundred and
five (105) days after inoculation.
Experiment (ii).—Guinea-pig inoculated on the 12th November 1892 with 0.3 c.c. of
blood taken from the Jugular Vein of Horse No. LXXIII. The hæmatozoon made its
appearance in the blood 12 days later on 24th November 1892. On the 5th, 8th, 13th and
15th December respectively the animal received subcutaneously 1.0 c. c. of blood drawn from
Bull No. I (inoculated, &c., as in the former experiment). Death took place on the 12th
March 1893, one hundred and twenty (120) days after inoculation.
Experiment (iii).—A Guinea-pig was inoculated on 21st September 1892 with 0.2 c. c.
of blood drawn from the ear of Bull No. III. The hæmatozoon made its appearance in
the blood 13 days later, on the 4th October 1892. The animal received subcutaneously
1.0 c. c. of fresh blood on the 5th, 8th, 13th and 15th of December drawn from Bull No. I
(inoculated, &c., as in experiments Nos. i and ii). Death took place on the 1st February
1893, one hundred and thirty-three (133) days after inoculation.
(II) Whether by subjecting Guinea-pigs to the influence of small quantities of bovine
blood at intervals of a few days and subsequently inoculating them with Surra, the disease
would be retarded or in any way affected by the previous injections of Bull's blood.
Experiment.—Two healthy Guinea-pigs were injected on the 5th, 8th, 13th and 15th
December 1892, respectively, with 1.0 c. c. of blood drawn from Bull No. I (inoculated on
24th March 1891, and re-inoculated on 22nd August 1892 with Surra). At a later date
18th December 1892, both Guinea-pigs were inoculated with Surra blood drawn from a
Guinea-pig previously inoculated from the horse in whose blood the hæmatozoon was
present.
No. I Guinea-pig died on 6th February 1893, fifty (50) days after inoculation.
No. II Guinea-pig died on 22nd March 1893, ninety-four (94) days after inoculation.
Remarks.—The Guinea-pigs in the first experiment succumbed in 105, 120 and 133
days, respectively, and on reference to the case of Bull No. I it will be observed that three
out of four animals of the same species when inoculated directly from the Bull and the
disease allowed to run its natural course succumbed in 144, 117 and 102 days respectively.
Consequently the average length of life in the former animals was 119 days against the 121
days in the latter, or a difference of three days in favour of those experimentally treated.
In the second series of experiments the two animals succumbed in 50 and 94 days re-
spectively. But it is impossible to draw conclusions from these few experiments ; further
trials will therefore have to be made.