ABSTRACT
John Snow was a physician and pioneering epidemiologist with two towering achievements from both fields: advancing the understanding of anaesthesia and explaining the spread of the disease cholera. Snow came from a working-class background and took up a medical apprenticeship in Newcastle upon Tyne at the age of 14, during which time he encountered the horrific effects of cholera in British cities. The particularly deadly 1830–1 cholera epidemic and the fact that its thousands of victims tended to be the poor, particularly influenced him. He moved to London in 1836 to take up work as a physician and, on again encountering cholera, became a sceptic of the miasma ‘bad air’ theory then held to explain the diffusion of the disease through the atmosphere. Another major epidemic in 1849 provided the backdrop for his writing the groundbreaking On the Mode of Communication of Cholera.
