The Principles of Epidemiologic Transition and the Experiences in Kenya

Abstract

Throughout history, man has ignited dynamic changes in his ecosystem. In a cascading and feedback manner, these changes have, in return, significantly impacted on his probability of survival by exerting critical pressures that have shaped the population sizes, life styles, life expectancy and disease status. This position has been compounded further by climatic changes which have arisen as a consequence of man’s activities that have disturbed the ecosystem balance. In deliberate efforts to place adequate food on the table, man has embarked on extensive land use thereby encroaching on new habitats and interrupting biodiversity balance. Within these new habitats, he has encountered new disease pathogens with expected consequences of wide oscillations in mortality rates. Migration as a result of conflicts, poverty, search for pastures and other forces have also thrown a critical spanner in these dynamics. In addition, the speed of mobility has become a key cog wheel in the process of change; in the 18th century, it took an average of six months to travel from one continent to another while today one can traverse three continents in twenty four hours. Industrialization coupled by global, regional and local socio -economic adjustments has also become a major pillar in the superstructure of these changes. The ultimate consequence of these changes on health has been one of definite transitions across phases of disease scenarios over time at both local and global levels. Phases of pestilence, receding pandemics and upsurge of chronic diseases have become evident at varying levels in different countries. The main objective of this review is to demonstrate from literature the underlying principles of epidemiologic transition and to highlight the experiences in Kenya.