Another defining moment for epidemiology

Many epidemiologists are obsessed with definitions. A 1978 paper entitled “Definitions of epidemiology” presented 26 of them, documenting how the subject had evolved from an original focus upon epidemics, to infections in populations, and on to broader concerns with all disease in populations. This enthusiasm has continued, culminating for the moment in the sixth edition of the International Epidemiology Association's A Dictionary of Epidemiology, which defines its subject thus: “The study of the occurrence and distribution of health-related events, states, and processes in specified populations, including the study of the determinants influencing such processes, and the application of this knowledge to control relevant health problems.” Many will find this definition awkward—but let us also note that its emphasis is now upon “health”.