Salud!

Much of the time, when people are furiously debating some question, it turns out they don't have any substantive disagreement after all -- they are arguing over the meaning of a word. On the other hand, it may not be quite that simple, because the words in question may be embedded in larger constructs, so that disagreements about their meaning can reflect differences in substance after all.

Sorry, this is a little bit complicated so bear with me. The field called public health is usually traced back to a mythologized incident in which the British physician John Snow traced a cholera epidemic to a public well pump on Broad Street in London in 1854. (Those of you who haven't already been thoroughly indoctrinated in this world historic event can read all about it here.) Public health emerged thereafter as a definite enterprise in the late 19th and early 20th century, on the part of physicians who were concerned with infectious disease control, with an initial emphasis on the water supply and hence a great interest in sewer construction, but expanding to other policies such as isolation and quarantine, restricting spitting in public (thought to spread TB), and so on. As antibiotics and immunization became available, the concerns of public health naturally followed the evolving technology and knowledge, but infectious disease remained at the core of public health research and practice through most of the 20th Century.

Inevitably, as infectious disease declined in importance, and as diseases of non-infectious origin, notably cancer and heart disease, correspondingly became more important to the disease burden and to mortality, public health increased its focus to modfiable risk factors such as smoking and nutrition. This fueled intense interest in how to influence people's behavior and required that social psychology be imported into public health. But these diseases area also bound up with social problems, for example corporate power verus regulation in the public interest, chemical (as opposed to fecal) pollution of water, and poverty. The belated observation that tuberculosis, before the era of antibiotics, was closely associated with social conditions, and then that human longevity in general followed a gradient in socioeconomic status -- education and income -- brought sociology and politics into the field as well. It is no longer accurate -- indeed it is preposterous -- to say that epidemiology is "the" science of public health, although a few people have still not gotten the message.

But a field which is now all about political issues and social problems is inevitably beset by philosophical conundrums, disputes that hinge on hidden value conflicts, and competing interests. The theme ingredient in this stew is, of course, the concept of health -- what is it we are trying to maximize after all?

The definition of health as used in the field of public health naturally gets mixed up with the concept as used in the field of medicine. Public health is concerned with health at the level of populations, and medicine, of course, with the individual. In both, the meaning of "health" is essential, and disputed, whether or not the disputants recognize that that is what they are talking about.

So, next time, I will review the evolution of the concept within medicine. Don't worry, this is all going somewhere. . . . I hope.