Epidemiology is the study of the distribution and determinants of health-related states in populations and the application of this study to disease prevention and control. The document traces the history of epidemiology from its early foundations in the work of Hippocrates and John Graunt to its modern applications in identifying risk factors for diseases and conditions. It discusses how epidemiology has evolved from a focus on infectious diseases to also study chronic diseases, injuries, behaviors, and genetic/molecular factors. The epidemiological transition framework describes stages in changing disease patterns as societies develop, from an early focus on famine/pandemics to modern burdens of noncommunicable diseases.

1. EPIDEMIOLOGY
The study of the distribution and determinants of health-related
states or events in specified populations, and the
application of this study to the prevention and control of
health problems.

2. INTRODUCTION
• Epidemiology is a fundamental science of public
health.
• Epidemiology has made major contributions to
improving population health.
• Epidemiology is essential to the process of
identifying and mapping emerging diseases.
• There is often a frustrating delay between
acquiring epidemiological evidence and applying
this evidence to health policy.

3. HISTORY OF EPIDEMIOLOGY
• Circa 400 B.C. Hippocrates suggested that
environmental and host factors such as behaviors might
influence the development of disease.
• John Graunt 1662 (London councilman): Published a
landmark analysis and quantify patterns of birth, death,
and disease occurrence, noting disparities between males
and females, high infant mortality, urban/rural
differences, and seasonal variations.
• William Farr 1800: Systematically collecting and
analyzing Britain’s mortality statistics.

4. HISTORY OF EPIDEMIOLOGY
• John Snow 1854 (father of the field of
epidemiology): Epidemiological studies of chronic
diseases began around the mid‐19th century.
• In the mid- and late-1800s, epidemiological methods
began to be applied in the investigation of disease
occurrence.

5. HISTORY OF EPIDEMIOLOGY
• In the 1930s and 1940s, epidemiologists extended
their methods to noninfectious diseases.
• The period since World War II has seen an explosion
in the development of research methods and the
theoretical underpinnings of epidemiology.
• Epidemiology has been applied to the entire range of
health-related outcomes, behaviors, and even
knowledge and attitudes.

6. HISTORY OF EPIDEMIOLOGY
• During the 1940s and 1950s, several studies were
initiated to examine the possible link between smoking
and lung cancer. One of them was conducted by Doll and
Hills.
• During the 1960s and early 1970s health workers applied
epidemiologic methods to eradicate naturally occurring
smallpox worldwide.
• In the 1980s, epidemiology was extended to the studies of
injuries and violence.
• In the 1990s, the related fields of molecular and genetic
epidemiology and took roots.

7. HISTORY OF EPIDEMIOLOGY
• Today, public health workers throughout the world accept and
use epidemiology regularly to characterize the health of their
communities and to solve day-to-day problems, large and
small.

8. HISTORY OF EPIDEMIOLOGY
• The last decade there has been increasing
concern expressed about the limitations of the
risk factor approach, and considerable debate
about the future direction of epidemiology.
• it has been argued that there has been an
overemphasis on aspects of individual lifestyle,
and little attention paid to the population-level
determinants of health.

9. EPIDEMIOLOGICAL TRANSITION
Definition:
• Changing in mortality and morbidity over the
time and place, referred as epidemiological
transition.

10. EPIDEMIOLOGICAL TRANSITION
 Epidemiological transition theory:
▫ First model presented by Omran in 1970s.
▫ Theory focuses on the “complex change in the pattern of
health and disease and on the interaction between these
pattern and their demographic, economic and sociologic
determinants and consequences”.
▫ Transition linked to improvement and advances in nutrition,
hygiene and sanitation and medical knowledge and
technology.
▫ Health care transition refers to the changes in organized
social response to health needs of the population and deals
with the way the health care system is organized to deliver
its services.

11. EPIDEMIOLOGICAL TRANSITION
▫ STAGES
1. The age of pestilence and famine:
 Fluctuating mortality in response to epidemic, famines and war
 Crude Death rate was 30- 50 from per 1000 population
 Birth rate was low
 Average age was 20-40
 Leading causes of death was infectious and parasitic disease such as
influenza, diarrhoea, and tuberculosis.
2. The age of receding pandemics:
 Death rate decreases and was 30 from per 1000 population
 Birth rate increases
 Average age counted was 55 year.
 Improve sanitation, hygiene and nutrition
 Later advance in medicine and public health programs
3. The age of degenerative man-made diseases:
 Mortality decline until death rate become 20 from per 1000
 Birth rat increase an d life expectancy become 70 years
 Major causes of death was chronic degenerative and man mad diseases
related to radiation, accidents, food additives, occupational hazards and
environmental pollution.

12. EPIDEMIOLOGICAL TRANSITION
• Hybristic stage:
▫ In addition to previous stages by Roger and Hackenberg in
1987.
▫ He felt that original theory lacked reference to violence and
accidental death and death due to behavioral causes.
▫ Morbidity and mortality affected by man made diseases,
individual behavior and potentially distractive lifestyle.
▫ Individual behavior includes physical inactivity, unhealthy
diet, excessive drinking and cigarette smoking.
▫ Potentially distractive lifestyle example is HIV/AIDS.

13. EPIDEMIOLOGICAL TRANSITION
• The age of delayed degenerative disease
proposed by Olshansky and Ault in 1986.
▫ Rapid mortality decline in advance ages that are
caused by postponement of the ages at which
degenerative disease tend to kill.
▫ It is a result of public health measure and advance
in medicine technology.

14. EPIDEMIOLOGICAL TRANSITION
• Models
▫ Western or classical model
 Transition start in 19th century and was accuplained
by a process of modernization, and industrial and
social change.
▫ Accelerated model by Japan
 Change was based on general social improvement
such as nutrition, sanitation and medical advance.
▫ Delayed model
 Occur in developing countries
 Mortality decrease by modern medicine technology.