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Conv-Pdx

day, disease, lymph, vesicle, small-pox, areola and seen

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CONV-PDX.

cow-pox, Or vaccinia, is a disease with is natural to the milch cow, but never occurs in the human subject except as the result of direct vacci nation. In the cow it appears on the teats and udder as isolated spots, which at first are papular, but afterwards pass through the vesicular and pustular stages, as in true small-pox. They scab on the thirteenth or four teenth day, and fall off in the following week, leaving pits on the skin. This disease is now satisfactorily proved to be the real small-pox, altered in character and modified by its passage through the animal, but still capable, when conveyed to the human subject, of imparting as much protection as would be derived from a direct attack of the original disease.

It is now a fatniliar story how Edward Jenner, then living as apprentice to a surgeon in Gloucestershire, determined to investigate the truth of a belief, current in the neighbourhood, that milkers who had become inoc ulated with cow-pox in the pursuit of their calling, were no longer suscep tible to the contagion of small-pox ; and how, by careful observation and experiment, he succeeded in establishing the important conclusions—that cow-pox communicated by inoculation to the human subject did actually confer immunity from small-pox ; also that the disease, so en,grafted, might be transmitted indefinitely from person to person without any abatement of its protective power. Since Jenner's time the practice of vaccination has become universal, and to this great discovery we owe it that small-pox, as it used to be, with all its dreadful consequences, is almost unknown in the present day.

Symptoms and Course. —After the introduction of the lymph under the skin of a child previously unvaccinated the following is the course of the induced disorder. For two days no change takes place, but at the end of the second day, or beginning of the third, a small elevated papule is seen at the site of the puncture. This enlarges, and by the fifth or sixth day has become a circular raised pearly-gray vesicle, with a depression in the centre. The vesicle grows, and by the eighth day is fully developed. It is then seen as a flattened, round, gray-colored vesicle, still depressed in the centre and filled with a colorless lymph. It. does not remain stationary,

but begins at once to lose its transparency ; a red areola forms round its base and quickly spreads, so that by the tenth clay the vesicle is found seated on a hardened red base, with the red areola extending for one or more inches over the skin around. The vesicle has now become a pustule with purulent contents, and around it the subcutaneous tissue is hard and swollen. After the tenth day the areola gradually fades ; the fluid contents of the pustule undergo absorption ; and by the fourteenth or fifteenth day a scab has formed, which gradually loosens and becomes detached. The crust usually falls in about three weeks from the time of puncture, and in. its place is seen a round sunken scar pitted with little depressions.

The disease is at first purely local, but afterwards becomes general. According to Dr. Squire a continuous rise of temperature begins on the fourth or fifth day. This suddenly increases on the eighth day, and as suddenly falls a day or two afterwards, when the areola has ceased to ex tend itself. The maturation of the vesicle is also accompanied by other signs, showing that the disease has begun to affect the The child is restless and uneasy ; there is some digestive disturbance ; and the lymphatic glands in the armpit become tender. Sometimes a roseolous red rash makes its appearance on the affected limb, and may extend to the other extremities. This rash may become papular or even vesicular.

The above is the course of the disease when the inoculating lymph is taken from another child. Some practitioners prefer to use lymph ob tained directly from the cow. But with "primary" lymph there is more difficulty in operating successfully; and when the vaccination takes effect, the constitutional symptoms are more severe. There is also another dif ference. With such lymph the whole process is retarded. The papule does not appear until a week or even a longer time has elapsed, and the areola does not become complete until the eleventh or even the fourteenth day. The swelling and hardness around the pustule are greater, and the secondary rashes are more frequently seen. The scabbing stage is also prolonged, and the crust may not fall for a month or six weeks from the day of operation.

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