Introduction to epidemiology
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Epidemiology is the study of health-related states or events in populations, focusing on the distribution, frequency, and determinants of diseases. It aims to describe health problems, identify risk factors, and guide public health initiatives to improve community well-being. Key components include analyzing disease frequency, distribution over time and place, and identifying underlying causes or risk factors.
Introduction to epidemiology
- 1. Epidemiology
- 2. Epidemiology Epidemiology is the basic science of community Medicine. ‘Epi’ – among ‘demos’ – people ‘logos’ – study Epidemiology means the study among people.
- 3. Definition of Epidemiology •As per Perkins (1873) It is that branch of science which treats of epidemics. •As per Frost (1927) it is the science of mass phenomenon of infectious disease. •As per Greenwood (1934) The study of any disease as a mass phenomena. •As per MacMohan (960) The study of the distribution and determinants of disease frequency in man.
- 4. Definition of Epidemiology As per John M. Last (1988) Epidemiology is the study of the distribution and determinants of health related states or events in specified populations, and the application of this study to the control of health problems.
- 5. Epidemiology often more concerned with the well- being of society as a whole, than with the well- being of individuals. In these definition three components are common. •Study of the disease frequency (frequency of disease, disability or death and summarizing in the form of rates and ratios). •Study of the distribution (pattern of disease i.e. time, place, person). •Study of the determinants (underlying cause or risk factors).
- 7. • DISTRIBUTION • TIME :- WHEN OCCURRED • PLACE :- WHERE IT OCCURRED • PERSON :- AGE, SEX, RACE, OCCUPATION
- 9. Aims of Epidemiology According to IEA (International Epidemiological Association), 1. To describe the distribution and magnitude of health and disease problems in human population. 2. To identify the aetiological factors and risk factors in pathogenesis of disease. 3. To provide data essential to planning implementation and evaluation of services for prevention, control and treatment of diseases and setting of priorities among the services.
- 11. Difference of Epidemiology & Clinical Medicine CLINICAL MEDICINE EPIDEMIOLOGY 1. The unit of study is case or cases 1. Unit of study is the population 2. Concerned with disease in person 2. Concerned with disease pattern in population bothsick & healthy 3. Clinician gives diagnosis and treatment & prognosis of the case. The diagnostic techniques are refined and modified 3. Epidemiologist is interested in the source of infection,mode of spread & trend of disease. Evaluates the outcome of preventive & therapeutic measure & give clue to administratorfor effective management 4. The patient goes to the clinician. 4. Epidemiologist goes to the community.
- 13. Asking Questions Epidemiology has been defined as “a means of learning or asking questions… and getting answers that lead to further questions.” Related to health Events a. What is the problem? b. What is its Magnitude? c. Where did it happen? d. When did it happen? e. Who are affected? f. Why did it happen?
- 14. Cont…… • Questions Related to Health Action a. What can be done to reduce the problem? b. How can it be prevented? c. What action should be taken by the community? By the Health Services? By other sectors? d. What resources are required? e. How are the activities to be organized? f. What difficulties may arise in implementation?
- 15. Making Comparisons • The basic approach in epidemiology is to make comparisons and draw inferences. • Comparison between two or more groups (one group having disease or exposed to risk factors and the other group not having disease or not exposed to risk factors, or comparison between two individuals). • Epidemiologist weighs, balances and contrasts.
- 16. Uses of Epidemiology 1. In health care management • Making Community diagnosis • Planning and evaluation of health services. • Developing health policies. 2. Understanding disease process • Studying natural history of disease. • Searching for causes and risk factors. • Historic studies of rise & fall of disease. • Identification of syndromes.
- 17. Uses of Epidemiology 3. Uses in public health practice • Investigation of epidemics • Surveillance of disease • Making projection for future • Formulating medical teaching curricular 4. Assisting in Clinical Practice • Assessing effectiveness of treatment modalities • Assessing effectiveness of preventive modalities • Studying prognostic factor • Studying effectiveness of diagnostic modalities • Assisting in clinical decision making • Indispensable for basic planning, conducting and analysing clinical research
- 19. RATIO :A number or quantity of one item in comparision to the other. Both the items are not a part of each other. Eg. Sex ratio 1. New smear +ve : New smear -ve 2. New smear +ve : Extra pulmonary 3. Non seriously ill extra pulm. :Seriously ill extra pulm. PROPORTION :Measurement of the size of a part out of the whole, usually the whole taken as 100. If the fraction is too small, the base can be 1000 or any 10x. Numerator is always a part of a denominator.
- 20. Terminology used in Epidemiology Epidemic – The unusual occurenceof disease, specific health related behaviour (eg. Smoking) or other health related events (eg. Traffic accidents) in a community or region clearly in excess of “expected occurence.” Endemic – constant presence of a disease or infectious agent within a given geographic area or population group, without importation from outside throughout the year in certain parts of country. Sporadic – Scattered outbreaks of infectious disease in different parts. Pandemic – An epidemic usually affecting a large proportion of population occurring over a wide geographic area.
- 21. Exotic – Infection is imported from outside. Zoonoses – Infectious disease of animals transmitted to man. Eg. Rabies, plague Carrier – A person or animal who harbouring specific infectious agent without showing signs and symptoms of the disease. Communicable disease – Illness transferred directly or indirectly from the sick to the healthy person. Surveillance – The continuous scrutiny of the factors that determine the occurrence and distribution of disease and other conditions of ill health. Eradication – Termination of all transmission of infection by extermination of infectitious agent through surveillance and containment.