basic concepts of EPIDEMIOLOGY - Copy.ppt
- 1. BY ANNASTASIA KISHOMBE Date :23 January 2024
- 2. Learning Objectives • Define epidemiology. • Explain a brief background of epidemiology • Define common terminologies used in epidemiology. • Describe the relevance of epidemiology
- 3. Definition • Epidemiology is a Greek word Epi (upon) + demos (people) + logos (study). • Epidemiology is the study of the distribution, frequency and determinants of health problems and diseases in human population (Stanhope 2014). • It is the distribution and determinants of health, diseases, morbidity, injuries, disability and mortality in populations (Allender, 2014)
- 4. BACKGROUND OF EPIDEMIOLOGY Started with Hippocrates around 400-470 BC • Greek physician considered to be the first epidemiologist. • They considered that diseases affect both individuals and masses. • Examined health and diseases in a community by looking at geography, climate, seasons of the year, food and water consumed, habits and behavior of people.
- 5. Background ctd….. • Modern epidemiology began with concerns of epidemics and infectious diseases that killed many people in Europe. • Hence it is concerned with the health of the population rather than individuals. • Originally, people studied epidemic diseases such as Cholera and Small pox. • Today, it covers the whole range of health problems.
- 6. Cont… John Grunt 1620 to 1674 Founder of demography (the study of human populations) He is recognized for the value of collecting data and providing information about human illnesses and this forms the basis of modern epidemiology.
- 7. B. Classic epidemiology 1830-1940 William Farr 1807 to 1883 • Founders of modern epidemiology and physician. • Developed modern vital record system. • Collaborated with Florence Nightngale and compared their data. • Pioneered mortality surveillance, and anticipated many of the basic concepts in epidemiology.
- 8. Cont… John Snow 1830-1858 • Conducted epidemiological research on transmission of Cholera. • Used mapping and natural experiment comparing rates in groups exposed to different water supplies.
- 9. C. Modern epidemiology 1940 up to date Pearl 1938- Developed life expectancy of smokers Bradford Hill and Richard Doll 1950-1964 – Developed a.Hospital case control studies b.Cohort of Doctors c.Study designs
- 10. Cont… Robert Korch 1843-1910 • Discovered causal agents for antrax, Tuberculosis and Cholera.
- 11. Terms used in Epidemiology • Incidence: Number of new cases, episodes or events occurring in a particular population over a defined period time, commonly one year. .
- 12. Cont… Prevalence: Total number of existing cases, episodes or events occurring at a given time. Proportion of the population with the disease/condition
- 13. Cont… • Mortality rate: Number of persons dying of a given condition in a population. • Case: Any person who is identified as having a particular disease, condition or behaviour. • Incubation period: Average period from infection time to the appearance of signs and symptoms of the disease.
- 14. Cont… • Interrelationship of incidence, prevalence and mortality. • Each new (incident) case enters a prevalence pool and remains there until either recovery or death. • Thus Incidence – Prevalence -recovery or death
- 15. Cont… • Causality: Connection between a cause and its result or consequences or effect. • Exposure: Open to a risk • Sampling: The selecting of subset of a population for study. • Sample: A subset selected from a population to represent the entire population.
- 16. Cont… • Control group: A group of subjects that is compared with those subjects having an attribute of interest to control bias and provide comparison values for statistical test. • Carrier: A person or animal without apparent disease who habours a specific infectious agent. • Odds: The ratio of the occurrence of an event to that of the non-occurrence • Precision: Accuracy of a measure.
- 17. Cont… • Common source of outbreak: An outbreak that results from a group of persons being exposed to a common noxious influence, such as an infectious agent or toxin. • Infectiousness: Ability of an organism to be transferred from one person to another person. • Virulence: Severity of the dysfunction caused by an organism. ( or harmfulness of a disease or poison).
- 18. Cont… • Screening: Means sifting out. It separates people into groups requiring different interventions. • It divides people into those who have and those who don’t have the disease. • Endemic diseases: Diseases or conditions regularly found among particular population or in a certain area i.e. Malaria
- 19. Cont… • Epidemic: Unusual increase, often sudden, in the number of cases of a disease above what is normally expected in a specific population and area at a particular time OR • The occurrence of more cases of a disease than would be expected in a community or region during a given period of time
- 20. Cont… • Outbreak: Carries the same definition of epidemic, but is also often used for a more limited geographic area. • Pandemic: Occurrence of a disease that affects many people over a very wide area such as the whole country or world. • Disease surveillance: The on-going systematic collection and analysis of data and the provision of information which leads to action being taken to prevent and control a disease.
- 21. Cont… • Health Indicator: A health indicator is a measure designed to summarize information about a given priority topic in population health or health system performance. • Health indicators provide comparable and actionable information across different geographic, organizational or administrative boundaries and/or can track progress over time
- 22. Measures of mortality • Crude mortality rate: Annual rate that represents the proportion of people who die from any cause during the period, using mid year population as the denominator. • Infant mortality rate: A number of infant death before one year of age in a year per number of live births in the same year. • Case fatality rate: Number of deaths from a specific disease in a given period out of number of persons diagnosed with that disease.
- 23. Aims of Epidemiology • Obtain, interpret and use health information. • Practical interventions and programmes • Reduce disease burden
- 24. Importance of Epidemiology It helps to study the history of the disease • It looks at the tendency of the disease for the prediction of the trends • Results are useful in planning for health services and public health
- 25. Cont… Community Diagnosis • Ability to know diseases, conditions, injuries, disorders, disabilities, defects causing diseases, health problems or deaths in the country. • It provides the numerical data that determine existence of health problem, extent of the health problem and ability to predict future trends in the area.
- 26. Cont… Determines individual risks as they affect groups or populations. • It looks at risk factors, problems and behaviour that affect the group. • Risk assessment which are done ie health screening, medical exams and disease assessment.
- 27. Cont… Assessment, evaluation and research • Assists in defining areas of need, planning, provision and evaluation of health care services. • Provides objective criteria for the evaluation of health care services • Helps to identify problems to be studied and suggests areas for further investigation.
- 28. Cont… Determine the causes and sources of diseases • Findings allow for control, prevention and elimination of causes of diseases, conditions, injury and disability.
- 29. SUMMARY ANY QUESTIONS?
- 30. THANK YOU!!!!!