Epidemics

Nearly a quarter of a century ago, Malcolm Gladwell wrote The Tipping Point in which he explained how little things could suddenly add up to cause huge change, in phenomena as diverse as the popularity of Hush Puppies and the reduction of crime in New York City. The book achieved its own tipping point and became a bestseller. It was followed by Outliers, which proposed among other things that in order to be really good at something you had to have practised at it for 10,000 hours. This is my first shot at reviewing a book by Gladwell, so I am several thousand hours short of practice. The phrase ‘tipping

Medicine was founded by Hippocrates in the 5th century BC. Doctors continued to study the Hippocratic texts into the 19th century, and many of the therapies, such as bleeding, purgatives and enemas, continued to be practised into the 20th. The standard Hippocratic account of disease was that it resulted from an imbalance of humours within the body. But this failed to explain how some diseases spread through populations at particular times. Among the earliest Hippocratic texts, Epidemics and On Airs, Waters, Places sought to explain this phenomenon. In 1850 the London Epidemiological Society was formed. The governing assumption of most of its members was exactly the same as those of