Your sincere friend,

Edward Jenner.

Berkeley, Gloucestershire, June 21st, 1798.

VACCINATION AGAINST SMALLPOX

I an inquiry into the causes and effects of the variole vaccine,
or cow-pox. 1798

The deviation of man from the stage in which he was originally placed by nature seems to have proved to him a prolific source of diseases.  From the love of splendour, from the indulgences of luxury, and from his fondness for amusement he has familiarised himself with a great number of animals, which may not originally have been intended for his associates.

The wolf, disarmed of ferocity, is now pillowed in the lady’s lap. [Footnote:  The late Mr. John Hunter proved, by experiments, that the dog is the wolf in a degenerate state.] The cat, the little tiger of our island, whose natural home is the forest, is equally domesticated and caressed.  The cow, the hog, the sheep, and the horse, are all, for a variety of purposes, brought under his care and dominion.

There is a disease to which the horse, from his state of domestication, is frequently subject.  The farriers have called it the grease.  It is an inflammation and swelling in the heel, from which issues matter possessing properties of a very peculiar kind, which seems capable of generating a disease in the human body (after it has undergone the modification which I shall presently speak of), which bears so strong a resemblance to the smallpox that I think it highly probable it may be the source of the disease.

In this dairy country a great number of cows are kept, and the office of milking is performed indiscriminately by men and maid servants.  One of the former having been appointed to apply dressings to the heels of a horse affected with the grease, and not paying due attention to cleanliness, incautiously bears his part in milking the cows, with some particles of the infectious matter adhering to his fingers.  When this is the case, it commonly happens that a disease is communicated to the cows, and from the cows to the dairymaids, which spreads through the farm until the most of the cattle and domestics feel its unpleasant consequences.  This disease has obtained the name of the cow-pox.  It appears on the nipples of the cows in the form of irregular pustules.  At their first appearance they are commonly of a palish blue, or rather of a colour somewhat approaching to livid, and are surrounded by an erysipelatous inflammation.  These pustules, unless a timely remedy be applied, frequently degenerate into phagedenic ulcers, which prove extremely troublesome. [Footnote:  They who attend sick cattle in this country find a speedy remedy for stopping the progress of this complaint in those applications which act chemically upon the morbid matter, such as the solutions