xxxiv
APPENDIX C.
Notes on Vaccination in which is included a description of the method now employed in Germany to
produce pure animal lymph, by W. A. C. ROE, F. R. C.S.,E., D.P.h., CAMB. , Surgeon-Lieutenant¬
Colonel, I. M. S., Civil Surgeon, Sialkot. Dated Sialkot, March 1893.
The principles on which a public system of vaccination should be based are not
only of interest and importance to the medical profession, but to the public generally, who
are mainly concerned ; and as there are many others than professional men to whom a
knowledge of these principles is indispensable, it is hoped that this brochure will
be sufficiently clear for a right understanding of these principles, as it is always a difficult
matter to present a technical subject so as to make it thoroughly intelligible to those who
have had no professional training.
Cow-pox is never met with in the human species except as the result of inoculation.
Only in the cow have we any certain knowledge of it as a natural disease, though it pro-
bably does occur as such in some other animals. It is a specific eruption in the cow, limited
to the teats and udder, and.is generally sporadic, but sometimes appears in an epidemic
form, especially in dairies. In the natural disease the period of inoculation is about three
or four days, but may be of longer duration.
The earliest symptoms noted are heat, swelling and tenderness, followed by the
appearance of hard pimples or papules, which increase in size as the disease progresses, and
after three or four days many of them become distinct vesicles with a central depression ;
the circumference of the vesicle then increases in extent and the centre becomes wide and
deep, until a flattened vesicle with a depressed centre is formed about the eighth or ninth
day, when they are fully developed. The colour of these vesicles varies according to their
age and the animal's skin, but they have always a shining look of a white or silvery aspect
with a dark centre, and around the base there is a pinkish circle only a few lines wide ;
but sometimes this inflamed and hardened base is much more extended.
About the tenth or eleventh day the disease is at its height, and after this the vesi-
cles become darker and hardened until they acquire their greatest size, when they begin to
dry and shrink, falling off about three weeks after their first appearance, and leaving a
smooth cicatrix where they were situated. During the time this process is progressing
scarcely any constitutional symptoms are developed, the animal feeding as usual. Some-
times the secretion of milk is lessened, but this is more apparent than real, and arises from
difficulty in milking. There are other kinds of pock of a spurious nature that may
sometimes be mistaken for the true cow-pox, but any careful professional man can usually
distinguish between the dirty brown or black vesications of these spurious pocks and the
true disease ; but the necessity for caution and accuracy is very great, as these spurious
pocks are in some instances highly contagious and afford no protection whatever against
subsequent attacks of small-pox.
Other diseases of a pustular character can be propagated from the cow to human
beings, and produce in them exceedingly severe symptoms, without affording protection of
any kind ; so that care and caution is absolutely necessary when making use of the natural
disease, that it may not produce unexpected results, more especially a false and delusive
idea that persons so inoculated are efficiently protected.
The true vaccine disease can be artificially produced in the cow by different
methods, and is constantly so induced in order to keep up the lymph supply ; and the
following are the means most generally employed for this purpose both in England and
on the Continent of Europe : —
1st.—Inoculation with lymph taken from other cows suffering from the natural
disease.
2nd.—By retro-vaccination, or inoculation with lymph which has originally been
taken from the cow and passed through the human body.
3rd.—By variolation or inoculation with human small-pox.
In all these forms the vesicles are limited almost exclusively to the points of
inoculation ; in other respects the course of the disease is just the same as in natural
cow-pox, but the local signs, especially in the case of inoculation with humanized lymph
that has been passed through the bodies of several animals in succession, are distinctly
less marked and active, and the affection runs a more rapid course.
Retro-vaccination, or the inoculation of cows with humanized lymph, is the operation
generally performed in India, where animal vaccination is carried on ; and the symptoms
and signs are so well known that it needs no detailed description ; but it is perhaps not so
well known that much depends on the lymph selected, and still more on the animal
employed for the purpose ; also that it is not always easy to inject calves properly with
humanized lymph, and furthermore, the lymph raised by retro-vaccination in the cow pro-
duces when vaccinated back into the human subject the results of ordinary vaccination,
only with less efficiency, during several removes, until it becomes again humanized, and
this lymph carried on from animal to animal attenuates and has constantly to be renewed.