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EPIDEMIOLOGY PPT3.pptx

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This document discusses theories of disease causation and screening in epidemiology. It describes several models of causation including the germ theory, epidemiological triad theory, and multifactorial causation theory. Determinants of disease are classified as agent, host, and environmental factors. The aims and types of screening programs are outlined, including mass, selective, multi-phase, and case-finding screening. Evaluation of screening programs involves experimental and non-experimental methods and comparing mortality rates between intervention and control groups.

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EPIDEMIOLOGY
TOPIC CAUSATION AND SCREENING OF DISEASE IN EPIDEMIOLOGY Theory and models of disease causation. Determinants of disease. Screening of disease.
CAUSATION AND SCREENING OF DISEASE IN EPIDEMIOLOGY Disease is a dynamic process and it is just opposite to health. Disease is the condition by which body health is impaired, a departure from a state of health, an alteration of the human body interrupting the performance of body function.
Theory and models of disease causation: - 1) Germ Theory: - The germ theory became popular in early 20th century. According to this theory, there is one single specific micro- organism to every disease. This refers to one- to- one relationship between the causative agent and the disease. This is also called as single cause theory.
Theory and models of disease causation: - 2) Epidemiological Triad Theory: - It was not only the causative agent that was responsible for causing disease but also host and environment contribute to the occurrence of disease. This theory consists of three components Agent Host Environment.
Theory and models of disease causation: - Agent: - The agent is considered as primary factor without which a particular disease cannot occur. Host: - The host refers to human beings which come in contact with the agent. Environment: It facilitates the interaction of host and agent.
Theory and models of disease causation: - 3) Multifactorial Causation Theory: - The diseases are caused by multiple factors. This model helps the epidemiologist to understand the various associative causative factors, prioritize these and plan preventive and control measures for a particular disease.
Theory and models of disease causation: - 4) Web of Causation theory: - This epidemiological model suggests that there are cluster of causes and combination of effects which are related to each other and need to studied to identify possible interventions to reduce the occurrence of a particular disease.
Theory and models of disease causation: - 5) Devers Epidemiological Model: - This model composed of four major categories or factors such as human biology, lifestyle, environment and healthcare system. All these factors influence health status either positively or negatively.
DETERMINANTS OF DISEASE There are three elements classified as agent, host and environment which are determinants or responsible for causation of disease. 1) Agent Factors: - The disease agent is defined as an element, a substance, living or non- living or a force-
DETERMINANTS OF DISEASE intangible, the presence and absence of which may follow the effective contact with the susceptible contact or susceptible human host under proper environmental conditions; it serve as a stimulus to initiate or perpetuate a disease process.
DETERMINANTS OF DISEASE The disease agents are usually classified: Biological Agents Nutrient Agents Physical Agent Chemical Agent Mechanical Agent Social Agent
DETERMINANTS OF DISEASE 2) Host Risk Factors: - Demographic characteristics Biological factors Psychosocial and economic characteristics. Life style. Past history of exposure.
DETERMINANTS OF DISEASE 3) Environmental Risk Factors: - Biological environment. Physical environment. Psycho- social environment.
SCREENING OF DISEASE Screening is testing for infection or disease in population or in individuals who are not seeking health care. Example, serological testing for AIDS virus in blood donors, neonatal screening etc.
SCREENING OF DISEASE Aims and objectives of screening: - To sort out from a large group apparently healthy persons likely to have the disease. To bring those who are apparently abnormal under medical supervision and talent.
SCREENING OF DISEASE Uses of screening: - Case detection: People are screened for their own benefit, like cancer, diabetes, hypertension, etc. Control of disease: - It is prospective screening that people are screened for the benefit of others, HIV etc.
SCREENING OF DISEASE Uses of screening: - Research purposes: - To know the natural history of a disease. Educational opportunities It helps in public awareness about the disease.
SCREENING OF DISEASE Types of Screening: - Mass screening: - It is the screening of whole population or a subgroup to analysis whether or not exposed to the risk of having disease under study.
SCREENING OF DISEASE Types of Screening: - High risk or selective screening: - In this screening only those who are at risk to have a particular problem or disease.
SCREENING OF DISEASE Types of Screening: - Multi- phase screening: - It is the application of two or more screening test combining to a large number of people at one time than to carry out the separate screening tests for single disease.
SCREENING OF DISEASE Types of Screening: - Multipurpose screening: - The screening of a population by more than one test done simultaneously to detect more than one disease.
SCREENING OF DISEASE Types of Screening: - Case Finding screening: - The main objective is to detect disease and bring patients to treatment.
EVALUATION OF SCREENING PROGRAMME The screening programmes must be put into practice after proper evaluation by the following ways: 1) Methods: Experimental method: It conducts RCT of the screening test to compare the disease specific cumulative mortality rate between the intervention and control group.
EVALUATION OF SCREENING PROGRAMME Non- experimental method: There are methods like case control, cohort study and ecological study. 2) Measures of Effect: Comparison of survival experience. Comparison of disease specific mortality rate.
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EPIDEMIOLOGY PPT3.pptx

  • 2. TOPIC CAUSATION AND SCREENING OF DISEASE IN EPIDEMIOLOGY Theory and models of disease causation. Determinants of disease. Screening of disease.
  • 3. CAUSATION AND SCREENING OF DISEASE IN EPIDEMIOLOGY Disease is a dynamic process and it is just opposite to health. Disease is the condition by which body health is impaired, a departure from a state of health, an alteration of the human body interrupting the performance of body function.
  • 4. Theory and models of disease causation: - 1) Germ Theory: - The germ theory became popular in early 20th century. According to this theory, there is one single specific micro- organism to every disease. This refers to one- to- one relationship between the causative agent and the disease. This is also called as single cause theory.
  • 5. Theory and models of disease causation: - 2) Epidemiological Triad Theory: - It was not only the causative agent that was responsible for causing disease but also host and environment contribute to the occurrence of disease. This theory consists of three components Agent Host Environment.
  • 6. Theory and models of disease causation: - Agent: - The agent is considered as primary factor without which a particular disease cannot occur. Host: - The host refers to human beings which come in contact with the agent. Environment: It facilitates the interaction of host and agent.
  • 7. Theory and models of disease causation: - 3) Multifactorial Causation Theory: - The diseases are caused by multiple factors. This model helps the epidemiologist to understand the various associative causative factors, prioritize these and plan preventive and control measures for a particular disease.
  • 8. Theory and models of disease causation: - 4) Web of Causation theory: - This epidemiological model suggests that there are cluster of causes and combination of effects which are related to each other and need to studied to identify possible interventions to reduce the occurrence of a particular disease.
  • 9. Theory and models of disease causation: - 5) Devers Epidemiological Model: - This model composed of four major categories or factors such as human biology, lifestyle, environment and healthcare system. All these factors influence health status either positively or negatively.
  • 10. DETERMINANTS OF DISEASE There are three elements classified as agent, host and environment which are determinants or responsible for causation of disease. 1) Agent Factors: - The disease agent is defined as an element, a substance, living or non- living or a force-
  • 11. DETERMINANTS OF DISEASE intangible, the presence and absence of which may follow the effective contact with the susceptible contact or susceptible human host under proper environmental conditions; it serve as a stimulus to initiate or perpetuate a disease process.
  • 12. DETERMINANTS OF DISEASE The disease agents are usually classified: Biological Agents Nutrient Agents Physical Agent Chemical Agent Mechanical Agent Social Agent
  • 13. DETERMINANTS OF DISEASE 2) Host Risk Factors: - Demographic characteristics Biological factors Psychosocial and economic characteristics. Life style. Past history of exposure.
  • 14. DETERMINANTS OF DISEASE 3) Environmental Risk Factors: - Biological environment. Physical environment. Psycho- social environment.
  • 15. SCREENING OF DISEASE Screening is testing for infection or disease in population or in individuals who are not seeking health care. Example, serological testing for AIDS virus in blood donors, neonatal screening etc.
  • 16. SCREENING OF DISEASE Aims and objectives of screening: - To sort out from a large group apparently healthy persons likely to have the disease. To bring those who are apparently abnormal under medical supervision and talent.
  • 17. SCREENING OF DISEASE Uses of screening: - Case detection: People are screened for their own benefit, like cancer, diabetes, hypertension, etc. Control of disease: - It is prospective screening that people are screened for the benefit of others, HIV etc.
  • 18. SCREENING OF DISEASE Uses of screening: - Research purposes: - To know the natural history of a disease. Educational opportunities It helps in public awareness about the disease.
  • 19. SCREENING OF DISEASE Types of Screening: - Mass screening: - It is the screening of whole population or a subgroup to analysis whether or not exposed to the risk of having disease under study.
  • 20. SCREENING OF DISEASE Types of Screening: - High risk or selective screening: - In this screening only those who are at risk to have a particular problem or disease.
  • 21. SCREENING OF DISEASE Types of Screening: - Multi- phase screening: - It is the application of two or more screening test combining to a large number of people at one time than to carry out the separate screening tests for single disease.
  • 22. SCREENING OF DISEASE Types of Screening: - Multipurpose screening: - The screening of a population by more than one test done simultaneously to detect more than one disease.
  • 23. SCREENING OF DISEASE Types of Screening: - Case Finding screening: - The main objective is to detect disease and bring patients to treatment.
  • 24. EVALUATION OF SCREENING PROGRAMME The screening programmes must be put into practice after proper evaluation by the following ways: 1) Methods: Experimental method: It conducts RCT of the screening test to compare the disease specific cumulative mortality rate between the intervention and control group.
  • 25. EVALUATION OF SCREENING PROGRAMME Non- experimental method: There are methods like case control, cohort study and ecological study. 2) Measures of Effect: Comparison of survival experience. Comparison of disease specific mortality rate.