Part 74

The second assertion--that humanized virus succeeds more readily than the bovine variety--is still maintained by many, but, it may confidently be said, by few if any whose experience with good animal vaccine has been large. The truth is, that every large public vaccination service in the country is now carried on almost solely with bovine virus, and that results are thus achieved that were not dreamed of in former times. Individual experience cannot weigh against this fact, but may be explained, rather, by what modicum of truth there may be in the fifth proposition, or by the assumption (surely a legitimate one, in view of the number of irresponsible and ignorant purveyors of animal vaccine that have thrust themselves before the profession since the advantages of the practice were established by the labors of others) that those whose observation leads them to a conclusion at variance with that reached by the great majority of trained observers have really been unfortunate in the quality of the virus with which they have been supplied. Whatever the explanation may be, however, there is nothing more certain than that the use of animal vaccine, properly carried out, is daily furnishing results that have never been excelled, if they have been equalled, in the employment of humanized virus on a like scale.

The third suggestion--that the humanized virus acts the more promptly of the two, and is therefore to be preferred for immediate protection--is plausible, since the areola (the alleged sign of systemic infection) forms somewhat later around a pock produced by animal virus than around one that is the result of vaccination with the humanized variety. The difference is one of a few hours only at the most, and it is not by any means a general occurrence; still, we may concede that in this respect the use of humanized virus is to be preferred under certain circumstances.

As to the fourth statement--that humanized virus is more tenacious of its infective property--strictly speaking, there is not a particle of truth in it. In the case of liquid lymph preserved in capillary tubes it has the semblance of truth, but, for reasons that will be more fully set forth hereafter, that is because it is difficult to get the virulent portion of bovine lymph out of the tube. In the form of dried lymph (the only form that ought to be used) animal vaccine may be sent to all parts of the world, and may be kept any reasonable length of time and without {475} special care, without undergoing sensible deterioration, if tested by one who is familiar with its peculiarities and aware of the care that should be taken in using it. Under ordinary circumstances there is no difficulty about preserving animal vaccine with its energy practically unimpaired.

The statement that the use of humanized virus demands less special knowledge than that of bovine virus is conceded at once. That special knowledge is easily mastered, however, and no man fitted to practise medicine will look upon its acquirement as a bugbear or a hardship.

The impression, almost universal thirteen years ago, that humanized vaccine is less severe in its local and constitutional effects than the animal virus has been eradicated from the minds of all but those who still follow the teachings of the older writers rather than yield to what daily experience has been teaching during these thirteen years, or those who reason from exceptional cases rather than from a general drift. The truth seems to be this: with revaccinated adults animal vaccine acts somewhat more severely than the humanized virus; in infants, on the other hand, its action is not so violent as that of the humanized variety.

Concerning the seventh and last claim put forward in behalf of humanized vaccine--that it is less apt to give rise to irregular or spurious pocks--we may say that no form of irregularity has been observed by those who have lately used the bovine virus that was not well known to the older writers, who founded their observations wholly, or almost wholly, on the use of the humanized virus; nor is there any proof that such irregularities are more common now than formerly. The truth seems to be, that these irregular forms of pock seem to prevail at certain times, and not at other times, regardless of the particular stock of virus used, other things being equal. Why this should be so we do not know, but the fact is beyond dispute.

To sum up, then, we can only say that in barely one particular--that of promptness of action--can humanized virus justly be credited with any superiority, while in every other essential respect it is inferior, so far as any difference is to be observed.

What, on the other hand, are the points of superior excellence attaching to bovine virus? Setting aside certain extravagant assertions that have sometimes been made in its behalf, such as that it far exceeds the humanized virus in its protective virtue (which may be true, but is not yet proved), they may be put in general terms in the form of a denial of all the particular claims that we have enumerated as having been put forth for its rival. Such a denial, it has been seen, seems to the writer to be justified, save in the one particular that perhaps we should accord to humanized virus the merit of speedier action, and consequently greater certainty of protection, in cases of actual exposure to small-pox.

Besides these negative points in its favor, the foremost advantage of animal vaccine is the guarantee it gives that, properly used, no syphilitic contamination will result. On this point no argument is needed, for the cow is insusceptible to syphilis.

A second consideration in its favor is, that it can always be had in large quantities at short notice. The young practitioner of the present day can scarcely appreciate the importance of this fact, but whoever remembers the comparative helplessness in which, in past years, he has found himself in the face of a sudden outbreak of small-pox, not knowing which {476} way to turn for an adequate supply of vaccine, will at once concede its force.

On the whole, then, it must be said that bovine virus is entitled to the preference as a rule, but that possibly it is well to resort to humanized lymph of early removes under the special circumstances above referred to. On no account should long-humanized vaccine be used so long as our present stocks of animal virus maintain the excellence they have thus far preserved, nor should humanized virus of any sort be preferred in the general run of cases.

Passing now to a consideration of the various forms of vaccine, disregarding its source, there are practically these three: the crust, liquid lymph preserved in capillary tubes, and dried lymph.

Until recently the crust, or scab, was much used in this country. Its capability of being preserved unimpaired for a long time was a valid excuse for this, especially in regions remote from the great channels of communication, and it was in such districts that the use of the crust was chiefly practised. That excuse scarcely exists now, for there are few physicians who cannot obtain a better form of vaccine within a very short time. The objections to the crust are two: 1. Most crusts are inert. Especially is this true of bovine crusts, which are wellnigh worthless. It must be confessed, however, that when once a crust has proved itself active it may be trusted to retain its infective property for a very long time. The writer has made successful use of crusts seven years old that had made the voyage to Japan and back; and they were bovine crusts too. Still, the rule is, that crusts are untrustworthy. 2. Their use is apt to be followed by undue inflammation, probably of septic origin, for they almost invariably contain putrescent or readily putrescible elements. It has even happened to the writer to cut open a crust that to all appearance was typical and innocent, and to find in its interior a cavity occupied by a pulpy, stinking slough. Manifestly, such material is unfit to be introduced into the system of any human being.

In regard to liquid lymph in tubes, it is not much used in this country, and its employment elsewhere is on the decline. At first thought, it would seem to be the best form of all, but experience does not bear out this view. In this form humanized lymph is vastly superior to animal lymph, but with every possible care in charging and sealing the tubes it is not uncommon to find their contents putrid. There are low vegetable organisms that are supposed to prey on the vaccinad. If there is any truth in this supposition, those organisms are certainly favored in their destructive luxuriance by keeping the lymph liquid, thus furnishing them with the best possible culture-fluid. Be this as it may, the fact is well ascertained that tube-lymph does not keep well. It has been mentioned already that bovine lymph stored in tubes is decidedly inferior to the same form of humanized lymph. This was long ago recognized by propagators of animal vaccine, but the cause remained a mystery until Warlomont of Brussels suggested that it was due to one of the physical peculiarities of animal lymph--that, namely, as already hinted at, by virtue of which its formed elements tend to attach themselves to any surface presented to them, leaving the supernatant liquid a mere inert compound of water, albumen, and salts; so that in the case of tube-lymph the virulent elements remain attached to the glass, and only the inert constituents {477} are really used. This theory is exceedingly ingenious and plausible, but the writer is not aware that it has been proved. He does know, however, that in some South American countries, where calf lymph in tubes is used with success, the custom is to grind the tubes to powder, and inoculate with the resulting magma, glass and all. This practice is certainly not to be commended.

Dried lymph is the most efficient of all forms of vaccine, and, kept as it ought to be, it retains its infective power long enough to answer all ordinary requirements. The writer has used it three years old with success. It may commonly be counted on for six weeks. One fact should be borne in mind, however: the longer dried lymph has been kept the more care is necessary in its use, for by long keeping it becomes very hard, so that it is a work of patience to dissolve it off from the surface on which it was deposited. Failure to accomplish its solution is the most common cause of a lack of success in its employment.

The various forms of stored vaccine are esteemed by the writer in the following order: 1, dried bovine lymph; 2, dried humanized lymph; 3, humanized tube-lymph; 4, humanized crusts; 5, bovine tube-lymph; 6, bovine crusts.

The age and other circumstances under which it is best to vaccinate children constitute a point for practical consideration. It may first be mentioned that pre-natal vaccination has been advocated by some authors; that is to say, the vaccinal infection of the foetus in utero by vaccinating the mother during gestation. There seems to be respectable testimony going to show that the end may thus be accomplished, but a weighty objection arises in the fact that this mediate vaccination of the foetus produces no physical sign of its success, so that doubt must always be felt as to whether or not the procedure has been efficacious. Moreover, it is seldom indeed that a child needs protection before its birth, provided we protect the mother, for it is well known that vaccinia will overtake and destroy the variolous infection, even when the latter has had two or three days' start. The practice has been chiefly urged by Bollinger. It is not likely to come into general use.

There is no special objection to vaccinating an infant at any time after birth, but usually it is well to defer the operation until the child is about three months old, unless there is actual danger of exposure to small-pox. Yet it is not well to postpone vaccination until the period of dentition, for the combined irritation of the two disturbing elements may prove decidedly uncomfortable if not serious.

Something is to be said as to the time of the year to be chosen. In New York the bad custom prevails, especially among the poorer classes, of having children vaccinated only in April, May, or June--just the part of the year in which erysipelas is most rife. The hot months should not generally be chosen, for any source of irritation is apt to be felt more severely by infants during the summer heat. However, no circumstances should be looked upon as a positive bar to vaccination in case of actual danger of exposure to small-pox, and in large towns children should never be taken into public conveyances or carried into any promiscuous assemblage until they have been protected by vaccination.

The next question is as to the part of the body that should be selected for the inoculation. The region of the insertion of the left deltoid muscle {478} is usually chosen--the left rather than the right, because most nurses habitually carry an infant on their own left arm, so that the child's left arm is uppermost, and hence less exposed to injury. The region of the deltoid insertion is comparatively free from the irritation of muscular contraction, and it is easily accessible. If two insertions are made, it is well to make one of them over the deltoid insertion and the other at a point about an inch distant on the line of the posterior border of the same muscle, for there the lymphatic connection with the axillary glands is less free, so that adenitis is not so much to be feared. To avoid a scar in a locality that may be exposed to view on certain occasions some mothers prefer that their daughters should be vaccinated on the lower limb. To this there is no special objection, further than that the lower limb is rather more exposed to rough handling than the arm. If the leg is chosen, the point of junction of the two heads of the gastrocnemius is an eligible situation.

The actual operation is performed in various ways. The old inoculators generally made an incision through the whole thickness of the skin, so that a pellet of subcutaneous fat rolled up into the little wound. This is wholly unnecessary; furthermore, it is objectionable, for it decidedly increases the risk of inflammatory complications. Still more to be avoided are the methods by inserting a seton imbued with the virus and by hypodermic injection or other like procedures. The best way is, simply to remove the horny layer of the cuticle, so as to expose the succulent portion of the epidermis. This surface is somewhat red, and from it a slight exudation of lymph will be observed, but there need not be the least flow of blood. By this procedure it is not uncommon to vaccinate a sleeping child without waking it. It is not only admissible, but preferable, not to wound the derma at all. Such an abrasion is easily made with an ordinary lancet, which, contrary to the advice sometimes given, should be very sharp; but no cutting or scratching should be done with it, only scraping with the convex part of its edge, precisely as in using an ink-eraser. Scratching instruments (such as the rake-like vaccinator often used or a row of needles set in a handle) are not easy to adapt to varying degrees of plumpness of the arm, and are apt to make too deep scratches, one at either side, while the skin between the two is scarcely touched. Whatever instrument is chosen, it should not be used again until it has been thoroughly cleansed--made chemically clean--which can be accomplished only by heating it or by wiping it off and then dipping it into a strong disinfectant solution.

Some individuals are refractory to vaccination, but complete insusceptibility is exceedingly rare. Various expedients have been resorted to in rebellious cases, such as vesication with ammonia-water, maceration of the skin for some hours with glycerine, and the like. The writer has known these devices to succeed, but he has not seen the slightest advantage in the plan recommended by Ceely, that of using a wound some hours old rather than one just made, although he has tried the experiment many times. It is not necessary to make a large abrasion; one as large as the little finger-nail is ample.

The next step is to apply the virus, and it should be so applied as to bring it into contact with every part of the denuded surface. In what is known as arm-to-arm vaccination, or its equivalent, calf-to-arm {479} vaccination (by all means the most successful method, although not often practicable in this country), the liquid lymph, fresh from the vaccinifer's pock, is simply applied, when it will at once become diffused over the abraded surface without any special pains being taken to accomplish that end.

If dried lymph is used, particular care should be taken to see that it is actually dissolved and transferred from the substance on which it was dried to the abraded surface. Failure to accomplish this is the cause of almost all the lack of success that inexperienced vaccinators meet with. The lymph should be moistened with water, or, if it is quite old, with glycerine, before the abrasion is made, so that it may have time to dissolve. It should then be rubbed upon the abraded spot vigorously, and at least for the space of a full minute.

In the use of tube-lymph no other precautions are necessary than in arm-to-arm vaccination, but, simple as this method is, its results are unsatisfactory.

Crusts should be reduced to a powder, and then made into a thin paste with water or glycerine. A convenient way of powdering a crust is to rub it on a file or between two files. The paste is to be well rubbed upon the abrasion. The insertion of a solid piece of crust into a valvular incision is not to be recommended.

When the operation is finished it is well to keep the arm bare for about five minutes, but not necessarily until the spot has become dry. It is not well to apply any sort of plaster, but means should be taken to prevent the underclothing from sticking to the abrasion. For this purpose there is no objection to the shields that are furnished by the surgical instrument-makers. Usually, however, nothing of the sort is necessary.

THE STORAGE AND PRESERVATION OF VACCINE VIRUS.--Lymph should usually be taken on the eighth day, inclusive--never after the areola has formed. On the other hand, the writer's experience does not lead him to coincide with those who state that the earliest lymph that can be obtained is the most energetic. If it is to be dry-stored, the substance to be coated with it (slips of quill, ivory, wood, whalebone, glass, and the like) should be laid gently in the pool of lymph that exudes on puncturing the pock, and allowed to dry, preferably without the aid of artificial warmth. The layer of lymph should be plainly visible after it has dried. A second coating is advisable, as it serves to preserve the first.