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and Chicken - Pdx Cow-Pdx Vaccination

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COW-PDX VACCINATION, AND CHICKEN - PDX. (Plates XXVII. and XXVIII.) In spite of inoculation, practised as de scribed in the preceding paragraphs, the mor tality from small-pox seemed to be on the increase in Britain, when, in 1798, Edward Jenner, a surgeon practising in Gloucester shire, published an inquiry into the causes and effects of cow-pox, and introduced the method of inoculating cow-pox as a preventa tive of small-pox. To this method the term vaccination has been applied, the word being derived from the Latin word vacca, a cow.

is a disease of oxen, manifested by the appearance, usually on the teats and udders of cows, of pocks, which almost exactly re semble those of small-pox. There is also a disease of the horse, called sup posed to be the same disease to which the term grease is applied, which is believed to be the same disease as cowpox. Cow-pox is a con tagious disease, and is liable to break out as an epidemic among cattle. Now, anyone who milks a cow, suffering from this disease, is liable to get on the hands some of the matter from the pocks, and if by a scratch or other pathway the matter can pass into the system of the person, that person is likely to contract the disease, which will show itself by the ap pearance of pocks at the infected parts, but by no other symptoms of any consequence. It had been for long a tradition among dairy-folks that anyone who had thus contracted cow-pox was safe from the risk of an attack of small pox. This notion Edward *Telmer had become aware of while still an apprentice to a surgeon, and it took firm hold of his mind. For years be did not cease to think of it, to inquire con cerning its truth, to make observations and experiments as well. For thirty years he worked quietly at the subject, and then he published his work on cow-pox, which com pletely established the truth of the old and vague idea, and raised it at once to the rank of a scientific fact. He gave details of persons who had accidentally contracted cow-pox, and who had remained proof against the infection of small-pox. He showed that persons who had thus been accidentally vaccinated were safe from small - pox even when small - pox matter was deliberately introduced into their bodies. He did more. He took matter from the pocks of a cow and introduced it into the skin of a child. In time this child showed the pocks of vaccination, now so familiar to every one. With matter from this child he vac cinated a second, and with matter from the second he vaccinated a third, and so on through five generations. Then into the body of the child vaccinated last he introduced small-pox poison and found it proof against the disease.

This was convincing evidence that the matter of the cow-pox could still protect from small pox even after it had passed through the systems of many persons in succession. It was not, therefore, necessary to go back to the cow for matter. After the publication of Jenner's work his statements were subjected to tests of the utmost severity, and were found to be per fectly unassailable. Thus at the London Small pox Hospital, in the two years following that of Jenner's publication, 7500 persons were vac cinated, and about one-half were afterwards inoculated with small-pox poison without the slightest effect.

Course of the Vaccination Pocks.— When a person has been properly vaccinated, nothing appears where the matter has been inserted till the second or third day, when a small red pimple shows itself. This grows larger and becomes, by the fifth or sixth day, a rounded grayish bleb tilled with clear fluid, and usually not raised in the centre. It goes on becoming larger till the eighth day. After this the clear contents begin to become yel lowish, the skin round the pock becomes red, inflamed, and thickened, and by the tenth day the skin for some distance round the pock is deeply red and hard, and the contents of the pock have become yellow matter. The pock now begins to dry up, and the inflammation and hardening round about to lessen, till by the fourteenth or fifteenth day the pock has changed to a dry dark scab, which falls about the twentieth day or a few days later, leaving a scar in the skin presenting numerous little pits, the surrounding inflammation having dis appeared. If the vaccination has been success ful the scar remains for life, and is easily recognized. A scar not well marked means imperfect vaccination; and, of course, the de gree of safety from small-pox varies with the degree of effect which the vaccination matter has produced in the body of the person. Dur ing the progress of the pocks the person ex hibits signs of being generally affected, but not as a rule, before the eighth day. There is some degree of feverishness, restlessness, irritability, and disturbance of digestion, which soon pass off, but still indicate that the vaccination has produced more effect than simply a pustule at the place where the matter was inserted. If the pocks do not pass through the stages described, if, for example, a scab is formed on the fifth or sixth day which soon falls, the vac cination is not perfect and the protection is not complete.

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