OPTOMETRY · SEMESTER 2
Describe Concepts Of Epidemiology In Disease Prevention
Epidemiology and Biostatistics
Describe the concepts of epidemiology in disease prevention
Learning Objectives
- By the end of this session, students are expected to be able to:
- Define terms used in epidemiology
- Define health and disease
- Describe Natural History of disease
- Outline key applications and achievements of epidemiology
- Explain the determinants of health and disease
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Explain factors related to health and disease
- Distinguish factors related to health and disease
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Epidemiology
- The word epidemiology comes from the Greek words
- epi = meaning on or upon
- demos = meaning people
- logos = meaning the study of or doctrine
- Thus the word “epidemiology” simply means the study of what is happening to people
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Definition of epidemiology
- As per perkins 1873 it is that branch of science which treats epidemics
- As per frost 1927 it is the science of mass phenomenon of infection disease.
- As per greenwood 1934 the study of any disease as a mass phenomena
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Describe Concepts Of Epidemiology In Disease Prevention
Epidemiology is often more concerned with the well-being of society as a whole, than with the well-being of individuals.
In these definitions, three components are common.
Study of the disease frequency(frequency of disease, disability or death and summarizing in the form of rates and ratios).
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Study of the distribution (pattern of disease i.e. time, place, person).
- Study of determinants (underlying cause or risk factors).
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Definition of epidemiology
« 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.
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Definition of terms used in epidemiology
- Distribution is concerned with the frequency and pattern of health events in a population
- Distribution:
- What, who, when, and where
- Frequency: number, rates, and risk
- Quantify diseases to determine magnitude
- Patterns: time, place, and person
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Definition of terms cont…
Frequency: refers to the number of health events e.g. Number of cases of meningitis, Number of cases of diabetes in a population, Number of people with mental disorder in a population, Number of children under one year of age vaccinated for measles.
Pattern of disease refers to the occurance of health related events or disease by time, place and person.
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Definition of Health
- Health: A state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. (World Health Organization)
- Definition of Disease
- Disease: A disorder of structure or function in a human, especially one that produces
- specific symptoms or that affects a specific part.
- Definition of agent
- Is an microorganism/microbe that is cable of causing a disease
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Describe natural history of disease
Definition: Natural history of a disease the course of a disease over time, unaffected by human interventions.
- Pathogenesis: Step-by-step origination and development of a disease.
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Stages of Pathogenesis
Pre-Pathogenesis: Occurs before the onset of disease; interaction between host, agent, and environment.
Pathogenesis: Interaction leads to discernible lesions or symptoms. Intervention can shorten or prevent this.
Post-Pathogenesis: Residual effects persist; new diseases may arise from post-pathogenesis of others.
Factors in Pre-Pathogenesis
- Host Factors: Age, sex, social class, personality, genetic makeup, etc.
- Agent Factors: Presence of an etiological factor necessary for disease.
- Risk Factors: Fixed (e.g., age) or modifiable (e.g., smoking).
Environmental Factors: Climate, altitude, population density, sanitation, etc.
Factors in Pathogenesis
Host-Agent Interaction: Time between onset and discernible disease or symptoms.
Outcome: May lead to recovery, disability, or death.Human Intervention can terminate or shorten this process.
Outline key applications and achievements of epidemiology
- The applications of epidemiology include;
- Disease surveillance
- Disease investigation
- Risk analysis
- Design of prevention strategies
- Natural history
- Diagnostic testing
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Achievements of epidemiology
- Community diagnosis
- Tools for data analysis
- Foundation for modern Public health
- Integration into various fields
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The determinants of health
- Many factors combine together to affect the health of individuals and communities.
- Whether people are healthy or not, is determined by their circumstances and environment.
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The determinants of health include;
- Income and social status
- Education
- Physical environment
- Social support networks
- Biology and genetic endowment
- Health services (availability and accessibility)
- Gender
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Key Points
As a discipline within public health, epidemiology includes the study of the frequency, patterns, and causes of health-related states or events in populations, and the application of the information gained to public health issues.
In epidemiology, our “patient” is the public at large—the community—and in “treating” our patient we perform several tasks, including public health surveillance, disease investigation, analytic epidemiology, and evaluation.
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Key points cont…
Epidemiology provides us with a systematic approach for determining What, Who, Where, When, and Why/How.
We use descriptive epidemiology to describe disease occurrence by person (Who), place (Where), and time (When).
We use descriptive epidemiology to portray the characteristics and public health of a population or community.
We use analytic epidemiology to sort out and quantify potential risk factors and causes (Why).
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aims/Uses/Applications of epidemiology
- Describe the distribution of diseases and burden in a population
Identification of etiological factors in pathogenesis Provide and analyze information for planning, implementation and evaluation of health status Study the natural history of disease
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reference
Bety R. K., & Jonathan A. C. S. (2003) Medical Statistics (2nd Ed.), Massachusetts: Blackwell Publishing Company Herold JM. Surveys and sampling. In: Greg M, ed. Field epidemiology. 3rd ed. New York: Oxford University Press; 2008:97-117.
Keneth, J. R., Sander, G., & Timoth, L.L. (2008).Modem Epidemiology (3rd Ed.). Philladelphia: Lippincott Williams and Wilkins.
McCusker J. (2001). Epidemiology in Community Health, Rural Health Series No. 9 (Revised Edition). Nairobi, Kenya: AMREF Varkevisser et al. (1995). Designing and Conducting Health Systems Research Projects,
