The epidemiologic transition theory. A preliminary update.

Abstract

The theory of epidemiologic transition is an application of epidemiologic inference and interpretation to population dynamics. The theory focuses on the complex changes in the patterns of health and disease and their demographic socioeconomic and ecobiologic determinants and consequences in the various population groups. In so doing the theory identifies mortality as a fundamental force in population change particularly in the early and formative phases of the transition with fertility as a crucial co-variable becoming the eventual pacemaker of population change later on in the transition when mortality is on its way to virtual stabilization at low levels. Druing the transition a long-term shift and eventual decline occurs in mortality and disease patterns whereby pandemics of infection are progressively (but not entirely) displaced by degenerative and man-made diseases as the leading causes of death. Changes during epidemiologic transition have a great impact on population composition and the pattern of population growth. Distinctive variations in the pattern pace determinants and the consequences of population change differentiate 4 basic models of epidemiologic transition. Whereas the more developed countries belonging to the classical and accelerated models experienced only low to moderate rates of population growth during the transition the less developed countries in the delayed model are experiencing growth rates of 2.0-3.5%/year. At this rate the population of those countries will double in 20 to 30 years. In those countries who are in the transitional varient of the delayed model this growth has been slowed by the initial fertility decline. Fortunately China with upwards of 1 billion people is apparently a part of the transitional varient. Despite the promising indications of the onset of fertility decline in a growing number of less developed countries the large gap that has developed between fertility and mortality in countries that have recently experienced the 2nd stage of epidemiologic transition (the age of receding pandemics) indicates that the unprecedented growth of world population will continue for some time to come. Charts illustrating changes in birth and death patterns spanning the last 2 centuries are given for New York City Mauritius the US as a whole Denmark Japan and Mexico. Included are trends in major casues of death and data by race for selected countries.