them who had much to do with dairies--gradually became aware of the
existence of the disease termed cow-pox, and of the fact that those
individuals who had accidentally contracted it were rendered proof
against the infection of small-pox. There is even fair testimony to
show that some of these people, particularly the English farmer,
Benjamin Jesty, relying on their observation to this effect, employed
intentional cow-pox inoculation as a protective measure. These facts,
however, do not detract in the least from the credit that all
Christendom has awarded to a man who subjected the popular impression
in question to the test of scientific investigation, proved its truth,
and demonstrated its value to the world. That man was Edward Jenner,
an English country physician. It was in the last quarter of the
eighteenth century that he entered upon his course of inquiry, and on
the eve of the present century he published his demonstration to the
world. It was not a discovery; it was not an invention: it was more
than either, "a matchless piece of induction," to quote the words of
Mr. John Simon. Filled as he must have been with the consciousness of
his great achievement, Jenner set this good example to all
investigators: that he did not make haste to convert the world; he
first convinced himself. It may almost be said, indeed, that, like
Minerva from the head of Jove, the rational and perfected practice of
vaccination sprang complete from Jenner's hands. Doubt and ridicule he
had to encounter at first, and afterward envy and detraction; but the
force of {466} his facts and the symmetry of his deductions were such
that the new inoculation soon spread through the broad world, and has
ever since maintained its sway, save with a few fanatical scoffers.
That vaccination really does protect against small-pox observation has
taught the whole civilized world, if we leave out of account the few
conscientious and intelligent doubters (made such, doubtless, quite as
much by the extravagant statements often put forth by those who from
time to time think it incumbent on them to defend vaccination, as by
their own misinterpretation of facts) who are to be found associated
with the noisy little body of actual opponents of the practice. One of
the most injurious statements ever made in the advocacy of vaccination
is, that it always protects if properly done. When one of these
illogical defenders of that proposition is confronted with an instance
that disproves his assertion, he falls back on the allegation that in
that instance the vaccination was not properly done. The manifest
absurdity of such an argument strikes the doubter most forcibly, and
inclines him to say to himself, Falsus in uno, falsus in omne.
Unbelief founded on this ground would never have arisen if the plain
truth had always been adhered to: that the protection afforded by
vaccination is not invariable, and that very often it is not
permanent. In the infancy of the practice these facts were not known,
but it is now many years since they became obvious to every
fair-minded observer. The misapprehension of facts lies chiefly in the
false deduction from the circumstance that the great majority of cases
of small-pox occur in persons who have been vaccinated. But the
explanation of this is very simple. Suppose that, of one hundred
persons vaccinated, twenty fail to be protected permanently; that all
persons not vaccinated are unprotected; and that throughout the
civilized world the proportion of vaccinated to unvaccinated persons
is as ninety to ten. Making no pretence of arithmetical accuracy, it
may certainly be said that all these suppositions are well within the
truth. It follows from them that in a community of ten thousand
persons there will be nine thousand who have been vaccinated, and one
thousand who have not. Of the former, eighteen hundred will have
failed to secure lasting protection. Therefore in case of an epidemic
there will probably be a proportion of eighteen cases of small-pox in
the vaccinated to ten in the unvaccinated; and yet this should not
obscure the fact that of the nine thousand vaccinated more than seven
thousand were absolutely protected, whereas of the one thousand not
vaccinated not one could escape the disease if exposed to it. When we
add the further observation that of the eighteen hundred cases of
small-pox among the vaccinated not more than thirty or forty would
probably prove fatal, while of the one thousand cases in the
unvaccinated about two hundred would end in death, we have a striking
demonstration of the efficiency of vaccination. As a matter of fact,
statistics show that the figures here given err rather in allowing too
little than in asserting too much in favor of vaccinal protection.
The question naturally arises, Why it is that vaccination protects
some persons and does not protect others?--reference being had, of
course, to permanent protection, for it is exceedingly rare for
temporary immunity to be attained if we exclude those instances in
which the variolous infection has taken place before the operation is
resorted to. This {467} question cannot be answered with any
certainty, but various theories have been brought forward, some of
which call for notice.
In the first place, it has been thought that the revolution of the
system termed puberty was fraught with such a radical change as to do
away with the mild modification due to vaccination. While this theory
has an air of plausibility, it seems to lack proof and not to be
upheld by analogy, for we do not find that children who have had
scarlet fever, measles, and the like often undergo those diseases a
second time on arriving at the age of puberty.
The only remaining theory that our limits will allow a consideration
of is that put forward by Marson of London, that the degree and
duration of vaccinal protection are proportionate to the perfection of
the vaccinal lesion and to the number of insertions made. In a large
experience with small-pox Marson found that the disease was more fatal
among those whose vaccinal scars were imperfect or few in number than
among those who bore evidence that several pocks had been produced and
had run a typical course. As to the influence of a perfect evolution
of the lesion, but little doubt can be entertained, for we have
already seen that in some instances its course is so different from
what it should be that no protection whatever seems to result. When we
come to consider the number of the pocks as affecting the degree or
the duration of protection, however, an obvious source of fallacy
arises in the fact that we cannot always be sure that some of the
scars on a person having a number of them were not the products of a
repetition of the operation several years after the first--that is to
say, a revaccination, the efficiency of which in restoring lost
immunity is now well established. Nevertheless, as long as the doubt
remains the best course to pursue seems to be to act as if Marson's
theory were in all respects correct, and vaccinate by multiple
insertions.
We have, then, no positive means of ascertaining who those persons are
that are likely to fail of lasting protection, or how long a time will
elapse before the cessation of their immunity will take place. The
only safety lies in revaccination. But after how many years should
revaccination be resorted to? It has been thought that this question
might be settled by noting at what age, or at what period after
primary vaccination, large numbers of people became susceptible of
revaccination. This test, however, is not altogether trustworthy, for
a renewed susceptibility to vaccinia by inoculation does not
necessarily imply that the liability to take small-pox by effluvium
has been regained. If it did, modified small-pox (varioloid) would be
far more common than it is, for it is certain that revaccination can
be made to succeed in a very large proportion of children long before
they have reached the age of puberty. The fact is, contrary to the
notions of the last generation, that success in revaccination is the
rule, not the exception. Formerly it was not expected to succeed, and
therefore no special pains were taken to ensure success.
Definite rules cannot be laid down as to the time that should be
suffered to elapse before vaccination is repeated, but in the great
majority of instances safety may be attained by revaccination every
five or six years, and always in the presence of an epidemic,
regardless of the lapse of time; also whenever one's mode of life is
to undergo a noteworthy change, {468} as in emigrating to a foreign
country, on entering the military service, and the like.
To sum up, then, vaccination almost invariably protects against
small-pox for the time being; generally for a long term of years;
sometimes for a lifetime. Often the protection is absolute; as a rule,
it is very nearly so; in rare instances it is trifling. In general
terms, it may be said that it is scarcely less protective than
variolous infection itself, for death from a second attack of
small-pox is by no means rare. Here the question comes up: Is
vaccination less protective, either in degree or in duration of
effect, than it was at the time of its adoption? Given a typical
vaccinia, we may unhesitatingly answer, No; but do we now so
invariably produce the disease in all its essential features as was
done in Jenner's time? Yes, provided we use proper virus and employ as
much care as was taken by the older physicians, who, trained to the
practice of variolation (the inoculation par excellence of bygone
days), did their work with a gusto now seldom witnessed. But there was
a time, now happily at an end, when it was not easy to obtain
thoroughly good virus, and when, therefore, the result was apt to vary
materially from the standard. This may be conceded without entering
upon the vexed question of the general deterioration of the Jennerian
stock of vaccine.
Besides immunity from small-pox, there are one or two sequelæ of
vaccinia that deserve mention before we proceed to consider what it is
better to class as complications. In the first place, vaccination has
been supposed to confer temporary protection against whooping cough.
The writer is not aware, however, of any precise data going to prove
either the truth or the falsity of this supposition.
Secondly, by virtue probably of the inflammation that attends the
evolution of the vaccinal pock, vaccination practised in the immediate
neighborhood of a small nævus often cures that blemish, and it has
been done for that purpose in many cases. It has no advantage over
many other measures, however, and there is the disadvantage that the
nævus may so mask the pock as to give rise to some doubt as to the
satisfactory character of the latter. The practice, therefore, is not
to be urged.
COMPLICATIONS.--These are local and systemic. Those of them that are
at all serious are rare, and can generally be traced to fortuitous
circumstances.
Inflammatory complications are usually due to undue traumatism at the
time of the inoculation, to injury of the pock, or to the previous
existence of a cutaneous disease or of some dyscrasia. Dermatitis is
the most common. It is usually a mere erythema, but in some instances
lymphangitis, lymphadenitis, phlegmonous inflammation, with diffuse
suppuration, may result. From injury of the pock ulceration and
gangrene may take place, and septic absorption may follow in their
train. These complications are to be treated as if they had occurred
from any other cause. Generally, the mere vaccination is not
responsible for them, but in some instances putrescent vaccine may be
adduced as their source. In such cases the complications, if they can
still be called so, are apt to make their appearance long before the
pock matures, even within forty-eight hours of the vaccination.
Inflammatory complications supervening on the full development of the
pock may invariably be set down as due to some cause not connected
with the quality of the virus employed.
{469} An undue amount of dermatitis is best treated with some mildly
astringent and anodyne application. The following liniment is
excellent for the purpose: Rx. Unguenti Stramonii oz. j; Liquoris
Plumbi Subacetatis fl. drachm ss; Olei Lini fl. oz. iv.--M. fiat
linimentum. As a rule, it is best to avoid poultices applied over the
pock itself, for they soften the tender structures that make up its
dome and render it prone to rupture, with all the consequences that
may follow its conversion into an open sore. When the latter accident
has occurred, dusting powders will ordinarily suffice to absorb the
discharge, and thus prevent putrefaction--either the ordinary toilet
powder or salicylized or carbolized powders, the basis of which may be
starch with a small proportion of the oxide of zinc. Besides the
antiseptics mentioned, iodoform, boric acid, etc. may be used to
advantage. Liquid applications are not usually so appropriate, but the
writer has known the proprietary preparation termed Listerine to
answer admirably.
Circumscribed collections of pus are to be treated as under other
circumstances, and burrowing is to be guarded against. It is only in
the worst cases that constitutional treatment of any sort is demanded,
and in these it should be of a supporting nature.
Passing from the simple inflammatory complications to those of a
specific character, we will first mention erysipelas. Genuine
erysipelas following vaccination is quite rare, but when it does occur
it is prone to prove serious. The writer believes that it always
depends on secondary infection--_i.e._ that the vaccinal wound becomes
the nidus of an erysipelatous contagium already existing in the
patient's surroundings, just as any other traumatic surface might, and
that the vaccinal virus has nothing whatever to do with it. Admitting
that improper virus is apt to give rise to dangerous inflammatory
complications, the latter are not really erysipelatous, whatever guise
they may put on. Erysipelas following vaccination calls for no other
treatment than what is proper for traumatic erysipelas under ordinary
circumstances.
We now come to the subject of vaccinal syphilis. The question of the
possibility of conveying constitutional taints along with vaccinia was
raised long ago, but, partly relying on certain theoretical tenets,
and partly because of the rarity of well-ascertained facts to shake
the blind confidence felt in the utter harmlessness of vaccination,
the profession fought the suggestion without properly investigating
it. In regard to syphilis, the broad assertion was maintained that two
infectious diseases could not affect an individual at one and the same
time: either syphilis would be communicated alone or vaccinia alone;
moreover, it was affirmed that the juices of a syphilitic person were
not capable of giving rise to the disease by inoculation unless they
happened to proceed from a syphilitic lesion. There was never
sufficient basis for the former of these two doctrines, and the latter
received a rude shock when it was shown by Pallizzari and the
anonymous physician of the Palatinate that the blood of a syphilitic
subject was capable of conveying the taint. Meantime, certain horrible
outbreaks of syphilis were reported, chiefly in Italy, that could not
reasonably be imputed to the ordinary occasions of syphilitic
infection. Even these occurrences, however, failed to shake the
general incredulity, especially in Great Britain, where until quite
recently men's orthodoxy in medical matters was gauged by their
obstinacy in refusing to {470} investigate, far less believe, the
slightest proposition unfavorable to vaccination, and where, also,
observations from beyond the limits of the empire were looked upon as
in all probability fallacious.
To a Frenchman, M. Viennois, we are indebted for the first systematic
and fair-minded study of the subject of vaccinal syphilis. This writer
demonstrated that the Rivalta cases and those of other like outbreaks
were certainly due to vaccination, but he concluded that they owed
their occurrence not necessarily to the use of lymph from syphilitic
subjects, but to the fact that that lymph contained blood. By this
time it had come to be recognized that syphilis was inoculable by the
blood. But even Viennois's masterly essay, and the facilis descensus
it offered to those English authors who found themselves confronted
with proof positive of their error, failed to make any noteworthy
impression beyond the concession that syphilis might possibly be
communicable in vaccination, but that, if it were, the catastrophe
might easily be escaped by avoiding the use of lymph contaminated with
blood, and that, therefore, the danger was practically no danger at
all, for no one in England would think of using bloody lymph! In all
this the English were slavishly followed by our own countrymen. It is
proper to add, however, that Ballard of London did his best to present
the matter in a proper light to the British profession, and that it is
largely due to his labors and to those of Jonathan Hutchinson (the
latter of whom supplemented Ricord's discovery that vaccine lymph is
never free from blood with abundant clinical evidence of the existence
of vaccinal syphilis unavoidable by the mere observance of Viennois's
safeguard) that we are now freed from the clog of error in this
matter. Nor was it the English alone that so long baffled the
recognition of the truth; in the French Académie de Médicine, Jules
Guérin and his adherents fought desperately against it.
At the present day we know that syphilis is liable to be communicated
in vaccination, and that, too, without regard to visible blood in the
lymph employed. There are two ways of avoiding it. One is, to use
non-humanized lymph, since the lower animals are insusceptible to
syphilis.[1] This is simple. The other is, to select a human
vaccinifer that is free from syphilis. This is difficult. Too great
reliance, however, should not be placed upon the vaccinifer; it is
possible to convey syphilis even in the use of bovine virus. Suppose
two persons, A and B, are to be vaccinated at one sitting, A being
syphilitic. If A is vaccinated first, and the same lancet, imperfectly
cleansed, is used on B, it is plain that B will be inoculated not only
with vaccine lymph, but also with A's blood. It is of the first
importance, therefore, that this form of vaccinal inoculation of
syphilis should be carefully guarded against; and that can be
accomplished most certainly by using a fresh instrument for each
patient.
[Footnote 1: Practically, this is certain, although there is some
reason to believe that the disease may be conveyed to monkeys.]
From a medico-legal point of view it is important to note that
constitutional syphilis may follow vaccination, and yet have nothing
to do with it. Suppose an infant to be born syphilitic, but with no
visible manifestations of the taint. Let that child be vaccinated, and
let the syphilitic dyscrasia afterward break forth. The ordinary
inference would be that the syphilis was due to the vaccination; and
in most instances this view would certainly be urged by the syphilitic
parent, since it would {471} free him from suspicion. It is always
easy to disprove such an allegation, however, for syphilis
communicated in vaccination always shows itself first in the form of a
chancre at the site of the vaccination. Therefore in any given case,
unless this mode of onset can be proved, the syphilis is manifestly
not of vaccinal origin. Some observers, it is true, are of the opinion
that vaccination may evoke a pre-existing syphilis, to use Lanoix's
term--_i.e._ that it may hasten the appearance of the characteristic
manifestations, and even determine their localization at the site of
the vaccinal inoculation. But, even allowing the truth of that
proposition, in such a case the lesion would be constitutional, not
chancrous.
It is well, nevertheless, to take precautions against being placed on
the defensive in this way; and it may commonly be avoided by declining
to vaccinate infants under three or four months old, since inherited
syphilis generally manifests itself by that time. This prudence on our
own behalf should not be carried so far, however, as to lead us to
deny the benefit of vaccination to very young infants whenever the
prevalence of small-pox is such that they are in obvious danger of
exposure.
As regards its management, vaccinal syphilis does not differ from the
ordinary form of the affection, and hence demands no other treatment
than what is proper for the disease contracted in the usual way. It
simply originates in an extragenital chancre.
Concerning the conveyance of other constitutional taints in
vaccination our knowledge is very limited. The present tendency of
pathological investigation is, however, to accord inoculability to
many diseases that formerly were not imagined to possess that quality,
so that in regard to other affections than syphilis it is prudent to
use the utmost care in the choice of lymph. There is one supposed
safeguard that does not seem to have the slightest title to be so
regarded--namely, the notion that a typical pock cannot be developed
on a person affected with a specific cachexia. There is no truth in
the doctrine. Over and over again the writer has seen perfect vaccine
pocks on persons whom he knew to be syphilitic.
Cutaneous affections of a non-specific character are sometimes
observed to result from vaccination; that is to say, they follow close
upon its performance, without any other known exciting cause. It may
fairly be supposed that in many instances they would have shown
themselves even if the vaccination had not been performed, for it is
often the case that we are unable to speak positively in regard to the
exciting cause of an eruption. Several years ago a striking case in
point was related to the writer by a well-known physician of this
city, S. S. Purple, in whose practice it occurred. Purple had engaged
to vaccinate a child on a certain day, but for some reason the
vaccination was not done. In about a week from the appointed day,
however, erysipelas made its appearance, beginning on the left arm at
the usual site of vaccination, and pursued its course to a fatal
termination. To be sure, we are now speaking of non-specific
affections, but erysipelas illustrates the proposition perfectly,
notwithstanding its specific character.
Children with a tendency to eczema are prone to suffer an outbreak of
that disease as the result of vaccination. In Jenner's time, indeed,
it was considered not only that there was great risk of causing an
aggravation of any slight eczematous eruption by vaccination, but that
the mere {472} existence of the eczema, even in the most trivial form,
was likely to interfere with the success of the vaccinal inoculation.
This has been the general feeling of the profession. Quite recently,
however, many observations have been recorded tending to show that the
old dread of vaccinating an eczematous child was not altogether
warranted. The question needs further study, and, while it is probably
best to postpone the operation under ordinary circumstances, nothing
should induce us to withhold its protective influence where there is
any manifest danger of actual exposure to small-pox.