01:00 AM EST on Monday, March 14, 2005

THE PUBLIC-HEALTH LEADERSHIP in both London and Providence in the mid-19th Century was assumed by two unrelated physicians named Snow. Both were compelled by circumstance to confront the nasty complexity of cholera, a disease that killed more humans in the mid-19th Century than either smallpox or tuberculosis.

The London Snow was John Snow, born of humble parents in York on March 15, 1813. He lived but 45 years, but this frugal, solitary man would make enormous contributions to the welfare of mankind in the two brief decades of his professional life.

Snow was a quiet, abstemious man, and a vegetarian. As a youth he was apprenticed to a physician but then sought a more formal education with London's Royal College of Physicians.

By 1846, Snow had established himself as a reputable physician endowed with an inquiring, rational mind and an intuitive appreciation of the experimental method. The inaugural use of ether as a general anesthetic, in Boston that year, prompted Snow to consider anesthesiology as a career. And so, during the next few years, he labored to define the physiologic characteristics of gaseous agents with demonstrable anesthetic properties; he devised many of the pieces of apparatus needed to induce general anesthesia; and he demonstrated the critical need to eliminate carbon dioxide from the re-breathed air.

James Young Simpson's innovative use of chloroform for obstetrical anesthesia, demonstrated in 1847, stimulated Snow to adopt and vastly improve the medical use of this volatile gas. In the next few years Snow supervised the delivery of chloroform anesthesia in about 4,300 maternity and general-surgery cases.

On April 7, 1853, Snow was summoned to Buckingham Palace, where he successfully provided chloroform anesthesia for Queen Victoria in one of her many maternity confinements -- this despite the contentions of theologians that women, even the queen, were expected to bring forth their children "in sorrow," and that obstetrical anesthesia was therefore a willful disregard of divine commandment.

While the art and science of anesthesiology occupied much of Snow's brief life, there was yet another facet of his inquiring mind that left its mark on medical history. England, beginning in 1831, suffered from repeated epidemics of a poorly understood disease called cholera, with an appalling mortality rate.

Snow, an indefatigable record keeper and pioneer epidemiologist, reviewed the temporal and geographic distribution of fatal cholera cases in London. He concluded that the conjectured miasma (alleged toxic mists, said to cause cholera) could not possibly account for the manner in which cholera had spread through the community. He wrote: "The disease is communicated by something that acts directly on the alimentary tract and might attach itself to the mucous membrane of the small intestines and thereby multiply itself."

Snow offered this hypothesis of something multiplying years before Louis Pasteur and others would show the pathologic effects of multiplying bacteria in certain illnesses -- and decades before the germ theory of disease was widely acknowledged. Snow's understanding of the dynamics of cholera -- and his fervent belief that cholera was transmitted through the city's drinking water -- led eventually to practical measures that dramatically reduced the incidence of cholera in London.

The Providence Dr. Snow was Edwin Miller Snow, born on May 8, 1820, in Pomfret, Vt. His parents, Nathan and Rhoda Snow, encouraged him to seek a career in the ministry, but attendance at Brown University convinced him that his calling was medicine. Snow received his baccalaureate degree in 1845 and three years later, his master's degree in the sciences. An additional year at Columbia University's College of Physicians and Surgeons provided him with his M.D. degree.

Snow's first attempts at private practice, in Holyoke, Mass., met with limited success. His familiarity with Providence then led him to transfer his practice to this city. Other than his medical-school years in New York and a few brief professional junkets overseas, Snow ended up devoting his life to Providence and its suburbs.

Snow envisioned human disease in its larger context. And so, beyond the immediate medical needs of his patients, he invested his energies in such general areas as nutrition, public sanitation, prophylactic measures (including mandatory vaccination), and childhood education as critical elements in the health of the citizenry. And by 1855 he had given up his private practice to accept the post of city registrar and superintendent of health for Providence.

During the Civil War (1861-65), Snow was called upon by the Union Army to function as health and hygiene inspector of its many hospitals. Gradually, he assumed the national leadership of the emerging though still controversial field of medicine called public health. When there was a world convention of public-health epidemiologists (in an organization initially called the International Statistical Congress and later the International Public Health Association), Edwin Snow represented the United States. And the American Public Health Association elected Snow its first president.

Edwin Snow, who died in 1888, was a careful student of the complex interactions among lifestyle, personal hygiene, cleanliness of the food supply, and the general education of children. (He speculated that the most reliable bulwark against epidemics is an educated public.) His work in relating cholera to public sanitation in Providence did much to diminish the morbidity and mortality of this dread disease.

It should be recalled that before the 1831 epidemic in London, Providence had viewed cholera as a celestial response to the irreligious, the alcoholic, and the intemperate -- a form of divine punishment. Snow reduced cholera to a secular disease amenable to a number of sanitary measures.

In the decades after 1831, London and Providence confronted successive epidemics of cholera, with death tolls in the many thousands. And two men, each called Snow, were responsible for devising those rational public-health measures that radically reduced the lethal effects of the disease.

Stanley M. Aronson, M.D., a weekly contributor, is dean of medicine emeritus at Brown University.