VACCINATION About the beginning of the eighteenth century, when Europe began to show interest in the matter, accounts from many countries of various modes of inoculation with smallpox appeared. Perhaps the oldest method is the one practiced from the earliest time by the Brahmans. Their technique of vaccination, being much like ours of the present time, is of greater interest to us than the methods practiced in China, Arabia, and the Circassian races.
The external surface of the arm was rubbed with a dry cloth; then with a small instrument, a number of small incisions were made, just deep enough to bring the blood to the surface. Some cotton was then applied which had been impregnated one year previous with the contents of a pustule from an artificially inoculated case.
The result at first was an area of inflammation about the place of inoculation similar to that caused by our present vaccination, and that, as a rule, was followed by a slight smallpox eruption. However, some of these persons artificially inoculated became seriously ill, a consider able percentage of the cases even having a fatal termination. They also spread the disease among unprotected persons.
Because of these objections, this method of inoculation, extensively practiced in Europe about the middle of the eighteenth century, never became generally recognized and fell altogether into disrepute when the value of Jenner's vaccine inoculation became known.
During the latter half of the eighteenth century the observation was made in many places that persons inoculated with cow-pox were insus ceptible to the contagion of smallpox. Thanks to the research work of Voigt and others, we now know cow-pox to be an infection of the cow's udder with the smallpox virus from man. It was Jenner, an English physician, who, from 1770 to 17S9, on this foundation built up his great system, and discovered the man-to-man method of inoculating the variola obtained from the cow.
Great efforts to extinguish the disease were then put forth on a large scale. As early as the beginning of the nineteenth century, vacci nation as protection against smallpox became compulsory in most civilized countries. Later it was learned, that a single vaccination does not confer permanent protection against smallpox, and that revaccina tion from time to time was necessary. In 1874, the law in the German
Empire made vaccination and revaccination compulsory, and conse quently all danger of smallpox became practically nil. Other countries stopped half way, some requiring but a single vaccination, others, with consideration for personal freedom, permitted the law to be evaded (England, Austria).
The cause of the disease has not yet been determined with certainty. I pass over the enormous literature on this subject, because it has led to no conclusion. This much is certain, that the specific cause, no matter to which species of micro-organisms it belongs, is found very abundantly in the fresh pustules. Its growth on dead culture media has not yet been successful, although we can cultivate it on the skin of man, monkeys, cows, and rabbits, by introducing the contents of a pustule into an abrasion of the epidermis. These cultures result in clinical manifestations which I shall later describe in detail, and after a growth of eight to twelve clays they are destroyed by antibodies found in the organism. To prevent its destruction, the micro-organism must be removed from the living (animal) nutrient medium, before the ap pearance of constitutional symptoms. It may then be kept viable for a long time, either mixed with glycerin or in the dry state.
Inoculation on different species of animals produces marked changes in the virulence of the smallpox organism. The most important. practical. point is, that having repeatedly been inoculated into the calf, its virulence becomes greatly and permanently lessened, and does not regain virulence by inoculation in man. This reduced virus obtained from the species bovina is called vaccine, from vacca (cow). The most favorable cultural conditions the vaccine virus finds are in its continuous passage through man, from arm to arm (humanized lymph). This method of inoculation carried with it the danger of transmitting diseases of man, especially syphilis. The present method, therefore, for obtaining the virus in great amounts is never by direct inoculation from man to man. In most institutions a calf is inoculated with the virus obtained from man, and from this calf many other calves. The lymph from these calves is put on the market as animal lymph for vaccination of man.