36
VOLE
VACCINATION
[Vol. XXIII, Part I,
balanced, a state of resistance where there are lesser chances of exhaustion following
overstimulation.
Till such time, as detailed studies on the above problems have been carried out,
it would be wise to reserve our definite decisions regarding the value of vaccination
with the vole bacillus in the control of tuberculosis, may be in animals or in human
beings. Researches on these problems should find a very important place in the
programmes of scientists engaged in the formidable task of control of bovine tuber-
culosis.
As the things are we have to bear in mind the limitations of vaccination even
on heavily infected farms and so under no consideration should vaccination be used
to the exclusion of time-honoured anti-tuberculosis measures, such as enforcement
of hygienic precautions against the spread of the disease. Vaccination may be taken
only as a helpful adjunct and an additional weapon in the already existing armament
to fight the scourage of tuberculosis.
With our present knowledge, it seems that mass vaccination neither with the
B.C.G. nor with vole bacillus will ever be attempted to any advantage, for eradication
of cattle tuberculosis, as vaccination renders animals allergic and a very useful
method of detecting during life the presence of tuberculous infection, loses its effec-
tiveness to a very great extent. The writers are not aware of any successful experi-
ment carried out to eradicate bovine tuberculosis from any country by the use of
vaccines. In Portugal in 1928, vaccination was tried as a part of an official scheme,
but was abandoned in 1931 [Lucas, 1938]. The British Committee on Cattle
Diseases [Report, 1934] concluded that even if vaccination was effective, the regula-
tions necessary to govern its use would be as onerous and those necessary for an
eradication scheme.
It will be well to stress here the need for a wider interest in the study of pathology
and pathogenesis of bovine tuberculosis, and not simply to transfer concepts gained
by the study of human tuberculosis, otherwise we are likely to go very far from the
truth, as tuberculosis in bovines differs in some very fundamental ways from that in
human beings. For example 'it is known that the primary focus in cattle may
remain latent for many years or at the most progress very slightly [Bang, 1899,
372; 1908b, 488; M'Fadyeen, 1899c] but the complete healing which occurs in man
is apparently rare in the bovine [Bull, 1937; Stamp, 1944] and the lesions remain
'open'. This view is supported by much epidemiological evidence which shows
that if any animal reacting to the tuberculin test, even with very slight lung lesions,
is left in a herd, spread will be more or less rapid. The problem of bovine tuberculosis
is therefore, a very important one not only from the animal health and agricultural
economics point of view but equally so from the public health, and requires being
attacked from all the angles in the interest of national welfare. Unfortunately no
statistics have yet been collected to show the huge monetary loss that our country
suffers annually at the hands of this scourge, but this much can be said with confidence
that the loss runs into millions of rupees and as the years go by and animals are
brought more and more under domestication and are concentrated in organised
dairy farms, the losses are bound to increase each year, unless concentrated efforts
are made to control this course. At present our knowledge of bovine tuberculosis
in general and especially under Indian conditions is very meagre and there are very