Updating the epidemiological transition model.

The main feature of the epidemiological transition is a shift in the recorded causes of death from infectious diseases to other morbid conditions. This paper outlines modifications made to Omran's original model and stages of transition, and suggests that without a focus on aetiology and morbidity, these have been basically descriptive rather than explanatory, and potentially misleading because infections have been confirmed as causes of various chronic diseases. Common infections and related immune responses or inflammatory processes contribute to the multifactorial aetiology of morbid conditions that together make a substantial contribution to overall mortality, and infectious causation is suspected for many others because of strong evidence of association. Investigation into possible infectious causes of conditions frequently recorded as the underlying cause of death can be integrated into a framework for comparative research on patterns of disease and mortality in support of public health and prevention. A theory of epidemiological transition aimed at understanding changes in disease patterns can encompass the role in different conditions and chronic diseases of infections contracted over the life course, and their contribution to disability, morbidity and mortality relative to other causes and determinants.