MUKTESAR, FOR THE YEAR ENDING THE 31ST MARCH, 1925
21
of infection, with very successful results. The efficacy of serum in " stopping dead "
outbreaks while in actual progress has been dwelt upon in the preceding Report.
(c) Blackquarter vaccines and serum. The developments concerning the modifica-
tions in the form of prophylactic agents recommended for issue to the field for the pro-
tection of cattle against blackquarter have been mentioned in the preceding Report.
The form of vaccine issued for many years, consisting of a single dose of heated infected
muscle powder, corresponding with the first dose of the old ARLOING system, made up
for convenience of injection into " pillules," was issued to the extent of 28,800 doses
during the year, and 40,000 doses were prepared, as against 40,600 doses issued and 29,600
doses prepared in the previous year.
Although a vaccine manufactured according to the old system is undoubtedly of
value and has rendered good service for many years, particularly when administered
according to the original instructions, in two consecutive doses, of graded virulency,
the system has certain inherent defects, especially when for the convenience of the ino-
culator it is reduced to a single-dose system, and the infective powder is treated so as to
deprive it of any risk towards the inoculated animal. Consequently, the field services
were acquainted with the advances made in recent years in the preparation of prophylac-
tic agents claimed by reliable investigators to be quite dependable and, at the same time.
wholly devoid of risk to the inoculated animals in that they are" germ-free," and not,
as in the case with the old form of vaccine, dependent for their efficacy upon the persis-
tence in minimal numbers of living virulent germ spores. These " germ-free" products
take the form either of the filtrate obtained by passing a good liquid culture of the black-
quarter germ through a bacterial filter or the filtrate obtained by passing through a bac-
terial filter the pressed juice obtained from the well developed muscle lesion of an animal
that has succumbed to an artificial injection of the blackquarter germ. The latter pro-
duct is often known as an " aggressin," for its efficacy is held to depend upon some pro-
perty it contains in solution representing the aggressive factor that enables the microbe
to obtain a foothold in the tissues, and is not related to the toxins that are afterwards
elaborated by it. In fact, both kinds of products are claimed to be of very low toxicity,
but much evidence has been adduced to show that in some way they contain properties
that enhance very strikingly the activities of the blackquarter bacillus. However, an
animal inoculated with these fluids that contain the specific " aggressins " develop after
the lapse of a few days a strong active immunity against invasion with the germ—ap-
parently, in virtue of their tissues having responded by producing an" anti-aggressin."
The field authorities were also advised that the laboratory was prepared to comply
with any requests that might be forthcoming from them for supplies of the new, " germ-
free " products, and an endeavour was made in the first place to prepare stocks of the
" germ-free (broth culture) filtrate " to be issued for trial prior to the advent of the 1924
blackquarter season. The culture was grown in the medium recommended by MEYER
and STICKEL for obtaining an optimum growth of Bacillus botulinus (Journal of Infecti¬
ous Diseases, 1921, Vol. 31, pp. 501-540), incubated at body temperature for three or four
days, and then passed through a Chamberland candle. The dose was 10 c.c. Demands
for this product for trial came from the Central Provinces and other authorities for use
in badly enzootic areas.
The Superintendent, Civil Veterinary Department, Central Provinces and Berar,
in paragraph 27 of his Annual Report for the year 1924-25 states :—
" Recent scientific study of this disease under Indian conditions threw considerable
light on the specificity of ' Blackquarter in animals.' In this matter hearty thanks
may be given for the assistance rendered by the Director, Imperial Institute of Veteri-
nary Research, who has made it possible to introduce into the districts a method of
protective inoculation which bids fair to play an important part in the control of this
disease in the Province—556 trial inoculations were performed in villages where Black-
quarter had a seasonal prevalence and all these villages are reported to be free from the
disease during the year. In this connection the Deputy Commissioner, Bhandara,
writes ' the figure for Blackquarter is noticeable when it is remembered that in 1923-24
when there were no inoculations for this disease, 165 animals died of it, while in 1924-25
there was only one solitary outbreak and four deaths.' "
This result, however, cannot be relied upon as furnishing completely trustworthy
evidence regarding the efficacy of the product, in the absence of indication as to what
might have been the mortality without inoculation during the season when it was actually
applied. A demand was also received from Mr. R. Branford, I.V.S., Superintendent,
Government Cattle Farm, Hissar, for the product for trial upon the young stock in the
series of breeding centres which constitute the farm and upon which blackquarter has