The Enlightenment Spirit of Edward Jenner

Virtually all Americans over the age of thirty bear the faded remnant of a distinctive childhood scar. It does not represent some bizarre ritual formerly practiced in the United States, like tattooing or body piercing. On the contrary, it symbolizes benevolence and reason, for it is the scar left by a smallpox vaccination and as such represents the life-saving medical discovery of the scientist Edward Jenner (born May 17, 1749).

The Ultimate Scourge

The scourge of smallpox is ancient—Pharaoh Ramses V is thought to have died of the illness in 1157 B.C. Yet smallpox did not become a major pestilence in Europe until the rise of urbanization in the late 1500s. Then, in the 1600s, the growth of cities and the wash of armies across Europe turned smallpox into the most deadly infectious disease on the continent. During the 1700s, 1 in every 300 Londoners died annually from the disease. Or, looked at another way: 1 in every 15 London deaths resulted from smallpox, rising above 1 in 10 as the century wore on. In addition, a third of all blindness in Europe was due to smallpox, and of course it wrought terrible psychological damage, particularly on women, through the permanent pockmarks that remained in its wake. In 1750, a French physician estimated that a fourth of the population was ultimately killed, blinded, or disfigured by smallpox.

The first signs of hope arose early in the 1700s. Physicians traveling in Turkey had learned of a process called variolation, which sought to lessen the chances of a fatal bout of smallpox by inducing a mild but immunizing bout. This process involved making small incisions in the skin and inserting material taken from the scabs of someone who had had a mild form of the disease. Unfortunately, the identification of a suitable strain of the disease was imprecise and approximately one percent of all those treated died of the disease.

By 1800, an infinitely better solution had been found.

How the Discovery Was Made

Edward Jenner was born in Berkeley, Gloucestershire, in 1749 and at age fourteen was apprenticed to a surgeon. In 1770, he moved to a London hospital to complete his training but in 1772 returned to his hometown to become the local practitioner. Yet his was not a parochial mind. In fact, he was a wide-ranging naturalist and became a Fellow of the Royal Society in 1789. Seven years later, he made his monumental discovery by a process of observation, hypothesis, and testing that approaches the model of the scientific method.

Jenner began by attending to reports that smallpox was rare among dairy farmers, and especially among people who came into direct contact with cows. He knew that there was a disease called cowpox, which bore certain resemblances to smallpox. And though this cowpox could on occasion infect humans, it rarely had severe effects. Jenner reasoned that there was something about having cowpox that changed the patient's physiology in a way that prevented an infection with smallpox.

During an outbreak of cowpox, in May 1796, a dairymaid consulted Jenner about a rash on her hand. He diagnosed cowpox, and the patient confirmed that one of her cows had recently had cowpox. Jenner realized that this was his opportunity to test his prediction about the protective properties of cowpox. Using material from the dairymaid's lesion, Jenner inoculated an eight-year-old boy who had never had smallpox. He made two half-inch incisions on one of the boy's arms and inserted pus and lymph from one of the dairymaid's pustules. After three days, the boy developed swelling, redness, and a small lesion at the site of the inoculation. But in two weeks he was well again. At this point, Jenner knew that cowpox could pass from person to person as well as from cow to person.

The next step was to test whether the cowpox would protect the boy from smallpox. So, on July 1, Jenner inoculated the boy with pus from a case of smallpox—that is, he "variolated" the boy. Writing to a friend, Jenner said, "But now listen to the most delightful part of my story. The boy has since been inoculated for Smallpox, which, as I ventured to predict, produced no effect." (See www.jennermuseum.com )

In 1797, Jenner informally submitted to the Royal Society a brief paper describing his experiment, along with an account of the traditional folk wisdom of cowpox's preventative powers. It was returned to him with the hint that if he valued the scientific reputation he had established (with a paper on the nesting habits of the cuckoo), he should not argue for his idea on the basis of one experiment.

Unfortunately for Jenner, outbreaks of cowpox were relatively rare, and so it was not until early in 1798 that the virus was again available to him. At that time, he inoculated five more children and tested three of them against smallpox. He then formally published an account of his experiments, and his technique of vaccination spread, though not as rapidly as he had hoped. In America, Professor Benjamin Waterhouse of Harvard University became its leading advocate and soon found an ally in Vice President Thomas Jefferson, who wrote to him: "Every friend of humanity must look with pleasure on this discovery, by which one evil more is withdrawn from the condition of man."

Two Centuries Later

Like Jefferson, Edward Jenner was a man of the Enlightenment and believed in the intellectual and moral improvement of mankind. Possessing that spirit, he predicted in 1801 that "the annihilation of smallpox—the most dreadful scourge of the human race—will be the final result of this practice" of vaccination. And he was right. Since the Enlightenment, the core branches of science and medicine have generally developed rationally. As a result, the World Health Organization was able to declare in 1980 that smallpox had been eradicated worldwide. Only two laboratory samples remained, one in Russia and one in the United States.

Or so people thought. It now seems possible that other states may have secretly retained samples of the smallpox virus. And it now seems all too possible that there exist leaders in those states who so hate the ideals of the Enlightenment that they would again unleash upon humanity the terrible scourge of smallpox. That, Edward Jenner would never have predicted.

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