'Defying providence': a salutary new look at the history of smallpox.

Arthur W Boylston, Defying Providence. Smallpox and the forgotten medical revolution. Charleston, SC: CreateSpace, 2012; 282 pp. ISBN 978-1478232452 ‘Defying Providence tells the story of the many men and women who wrestled with their consciences to turn inoculation from a primitive folk practice into the most powerful weapon against smallpox in the 18th century.’ (p.10) Until the 18th century, the outcome of a smallpox infection was fated by providence. Between 10% and 20% of the infected died and, among the survivors, many remained stigmatized in their flesh and appearance for the rest of their lives. Plague had been public enemy number one of the 17th century. When its cyclic and deadly recurrences began to ebb, smallpox became the new scourge, a disease that killed princes and peasants alike. Lady Montague, who had had her children inoculated against smallpox in Turkey in 1718, popularized the technique in England. Still, it was a risky practice responsible for some deaths. Was inoculation more dangerous than a natural smallpox infection? Opinions were split until mortality among the inoculated and that of the naturally infected was compared. Inoculation reduced mortality by a factor of 10 in the 1720s, both in the UK and in North America. With this information the practice amplified. Many country doctors adopted it. In 1768, one of them noticed that some people working in farms did not have the usual clinical reactions following a smallpox inoculation. They seemed resistant. Many farm workers had previously contracted cowpox. This news spread among doctors, not among milkmaids. Could artificial inoculation of cowpox confer immunity against smallpox? Jenner’s brilliant idea led to the vaccine revolution, and finally the end of smallpox: ‘without inoculation the cowpox effect could not have been discovered. There was no folk tradition.’ The myth remains that the beautiful complexion of milkmaids spared from the disfiguring effects of smallpox ignited Jenner’s imagination, but it was likely the resistance to inoculation among farmers that opened the door to ‘vaccines’. A less-known aspect of the forgotten medical revolution of the 18th century is its impact on the American Revolution. General George Washington gave the landmark mandate to inoculate the colonial army. In America, the colonial and the English armies were not equally susceptible to smallpox. Most English soldiers were immune from previous infection or inoculation, while Washington’s troops, highly susceptible, were killed 10 times more by the disease than from combat. In 1777, surmounting defiance from state and army hierarchy, the Congress approved the plan to systematically inoculate its soldiers. The act was implemented during the next two consecutive years. ‘Thereafter,’ writes Boylston, ‘the threat to the revolution from smallpox was over. Inoculation became as much a part of soldiering as a musket […] Americans would have certainly lost the revolution without it because most American colonists had had little previous exposure to the virus, and therefore no immunity to it. When smallpox spread through susceptible soldiers, the force always disintegrated.’ (p.212). Still, inoculation had already weathered excessive hindrances; delays in inoculating the troops preparing to reach Quebec resulted in Canada remaining British. The style in Defying Providence is scholarly in its precision, paying attention to details, and citing primary sources extensively. But Boylston also has an undeniable ability for storytelling and suspense building. The result reads like a brilliant tale in which the practice of inoculation, after helping modern medicine forge its first research and conceptual tools, was later denigrated as dangerous and unacceptable when the public health preference shifted to vaccination. Smallpox was the main health scourge when the conditions for a science of epidemics (an epidemiology) began to exist. Boylston can therefore trace in these illustrious decades of the 18th century the early manifestations of comparative studies, ancestors of controlled trials, and of what came to be known as evidence-based or evidence-informed medicine. Defying Providence is a precious book about ‘one of medicine’s finest hours’, at the crossroad of the history of diseases, of medicine, and of epidemiology.