Uwoebwobsueb shene ehwvwnij

1. Prepared by: Tufail Ahmad
BS SURGICAL (GOLD MEDALIST), MPH
Demonstrator Surgical,
Training scientist in Fundamental of Biosafety and Biosecurity
The Agha Khan University Karachi

2.  The word epidemiology comes from the Greek words epi, meaning on or upon,
demos, meaning people, and logos, meaning the study.
 It is the study of frequency, distribution, and determinants of diseases and other
health-related conditions in a human population
and the application of this study to the prevention of disease and promotion of
health.
 Epidemiology involves collection, analysis and interpretation of health related
data.
 1.Study: Systematic collection, analysis and interpretation of data
 2.Frequency: the number of times an event occurs.
 Epidemiology studies the number of times a disease occurs.
 It answers the question How many?

3.  3.Distribution: Distribution of an event by person, place and time.
 Epidemiology studies distribution of diseases.
 It answers the question who, where and when?
 4.Determinants: Factors the presence/absence of which affect the occurrence and
level of an event.
 studies what determines health events
 It answers the question how and why?

4.  5. Diseases & other health related events.
 Epidemiology is not only the study of diseases.
 The focus of Epidemiology are not only patients.
 It studies all health related conditions.
 6. Human population Epidemiology diagnoses and treats
communities/populations, not an individual.
 Clinical medicine diagnoses and treats patients.
 7. Application Epidemiological studies have direct and practical
applications for prevention of diseases & promotion of health.
 Epidemiology is a science and practice.

5.  Generally, Epidemiology answers six major questions:
 1.How many
 2.Who
 3. Where
 4. When.
 5. How
 6. Why?

6.  Two major categories of Epidemiology.
 Descriptive Epidemiology Defines frequency and distribution of diseases and other
health related events
 Answers the four major questions: how many, who, where, and when?
 2. Analytic Epidemiology Analyse determinants of health problems
 Answers two other major questions: how? And why?

7.  Clinical epidemiology is the study of the determinants and effects of clinical
decisions.
 It is the application of principles of epidemiology to clinical medicine.
 Clinical epidemiology is the application of the principles and methods of
epidemiology to conduct, appraise or apply clinical research studies focusing on
prevention, diagnosis, and treatment of disease.
 Epidemiology is the basic science of Evidence-based Medicine/Practice.

8.  Occupational epidemiology is a subdiscipline of epidemiology that focuses on
investigations of workers and the work place.
 Occupational epidemiologic studies examine health outcomes among workers, and
their potential association with conditions in the workplace including noise,
chemicals, heat, or radiation, or work organization such as schedules.
 Occupational epidemiological research can inform risk assessment; development
of standards and other risk management activities; and estimates of the co-
benefits and co-harms of policies designed to reduce risk factors or conditions that
can affect human health.

9.  Experimental epidemiology is a type of epidemiological investigation that uses an
experimental model to confirm a causal relationship suggested by observational
studies.
 It studies the relationships of various factors determining the frequency and
distribution of diseases in a community

10.  Identify the aetiology or cause of a disease and the relevant risk factors
 To determine the extent of disease found in the community/the burden of disease
in the community
 How the disease is transmitted from one person to another or from a nonhuman
reservoir to a human population (To determine the extent of disease (Burden)
found in the community).
 To reduce morbidity and mortality from the disease. (To study the natural history
and prognosis of disease)
 Develop a basis for prevention programs

11.  To evaluate both existing and newly developed preventive and therapeutic
measures and modes of health care delivery


13.  Two possible approaches to prevention are a population-based approach & a high-
risk approach.
 In the population-based approach, a preventive measure is widely applied to an
entire population.
 For example, prudent dietary advice for preventing coronary disease or advice
against smoking may be provided to an entire population.
 Relatively inexpensive and non-invasive.
 Population based approaches is considered public health approaches.

14.  The approach to target a high-risk group with the preventive measure.
 A measure that is to be applied to a high-risk subgroup of the population may be
more expensive and is often more invasive or inconvenient.
 High-risk approaches more often require a clinical action to identify the high risk
group to be targeted.
 combination of both approaches is ideal.

15.  Endemic. A disease that exist permanently in particular geographic area or
population.
 malaria is constantly worry in some parts of Africa.
 Epidemic it is a rapid spread of infectious disease to a large number of people in a
given population within a short period of time.
 Dengue fever
 Pandemic it is the spread of infectious disease to several countries or continent or
whole world.
 HIV, Covid-19