In demography and medical geograph
INTRODUCTION In demography and medical geography, epidemiological transition is a theory which "describes changing population patterns in terms of fertility, life expectancy, mortality, and leading causes of death."[1] For example, a phase of development marked by a sudden increase in population growth rates brought by improved food security and innovations in public health and medicine, can be followed by a re-leveling of population growth due to subsequent declines in fertility rates. Such a transition can account for the replacement of infectious diseases by chronic diseases over time due to increased life span as a result of improved health care and disease prevention. This theory was originally posited by Abdel Omran in 1971. Pestilence and Famine: Mortality is high and fluctuating, precluding sustained population growth, with low and variable life expectancy vacillating between 20 and 40 years. It is characterized by an increase in infectious diseases, malnutritio...