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

6. Types of Epidemiology 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 Clinical epidemiology is the study of the determinants and effects of clinical decisions. It is the application of principles of epidemiology to clinical medicine. C linical 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 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 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. OBJECTIVES OF EPIDEMIOLOGY Identify the aetiology or cause of a disease and the relevant risk factors T o 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. OBJECTIVES OF EPIDEMIOLOGY T o evaluate both existing and newly developed preventive and therapeutic measures and modes of health care delivery

12. Two Approaches to Prevention 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.

13. high-risk approach 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.

14. EPIDEMIOLOGICAL TERMS 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