Epidemiological transition: Infectious to chronic diseases

The objective of this communication is to explain and demonstrate the process of epidemiological transition, using Mexico’s experience as an example. The concept of ‘epidemiological transition’ has been in use for at least 25 years; the phrase, coined by Abdel Omran in 1971, refers to a series of changes that all societies undergo with regard to illness and death in the population; epidemiological methods are applied to the study of populations. Epidemiological transition occurs in parallel with a demographic and technological transition. It consist of four main patterns of change: in causes of death (from infectious to chronic diseases), age at death, relationship between morbidity and mortality (communicable to non-communicable disease) and the social importance of disease. There are three models of transition: classical, accelerated and contemporary; another model called ‘extended’ has been observed and includes polarization, mosaic and countertransition. Some indicators that give a clear of the transition in Mexico during this century are increase in the population size, a decrease in the number of deaths and an increase in the number of deaths due to chronic diseases, with estimated projections that follow the same trend.