Theory
Omran divided the epidemiological transition of mortality into three phases, in the last of which chronic diseases replace infection as the primary cause of death. These phases are:
- The Age of Pestilence and Famine: Where mortality is high and fluctuating, precluding sustained population growth, with low and variable life expectancy, vacillating between 20 and 40 years.
- The Age of Receding Pandemics: Where mortality progressively declines, with the rate of decline accelerating as epidemic peaks decrease in frequency. Average life expectancy increases steadily from about 30 to 50 years. Population growth is sustained and begins to be exponential.
- The Age of Degenerative and Man-Made Diseases: Mortality continues to decline and eventually approaches stability at a relatively low level.
The epidemiological transition occurs as a country undergoes the process of modernization from developing nation to developed nation status. The developments of modern healthcare, and medicine like antibiotics, drastically reduces infant mortality rates and extends average life expectancy which, coupled with subsequent declines in fertility rates, reflects a transition to chronic and degenerative diseases as more important causes of death.
Read more about this topic: Epidemiological Transition
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