Intro to Descriptive Epidemiology PDF

EPIDEMIOLOGY | TRANS 1 LE Intro to Descriptive Epidemiology LISSA LUZ C. CALIMAG, MD, MPM-HSD, DFM | Lecture Date (...

EPIDEMIOLOGY | TRANS 1 LE Intro to Descriptive Epidemiology LISSA LUZ C. CALIMAG, MD, MPM-HSD, DFM | Lecture Date (01/16/2024) | Version 2 01 OUTLINE B. JAMES LIND I. Epidemiology IV. Uses of Epidemiology in II. Historic Developments of Public Health Policy and Epidemiology Individual A.Hippocrates Decision-Making B. James Lind V. Behavior of Disease in C. John Snow the Community D. William Farr VI. Case Concepts in III. Concepts and Terms in Epidemiology Epidemiology VII. Triangle of Epidemiology Figure 2. James Lind A. Broad Categories A. Traditional Book: A Treatise on Scurvy (1754) Epidemiology B. Advanced Model Identified the symptoms of scurvy and the fact that the disease B. Descriptive VIII. Disease became common in sailors after as little as a month at sea Epidemiology Transmission Concepts i. Aim IX. Modes of Disease CLINICAL TRIAL IN SCURVY ii. 3 Basic Epidemiologi Transmission Questions A. Direct iii. XX B. Indirect iv. Activities in C. Airborne Epidemiology X. Summary Must Lecturer Book Previous Youtube ❗️ Know 💬 📖 📋 Trans 🔺 Video LEARNING OBJECTIVES ✔ Define epidemiology ✔ Identify selected activities performed in epidemiology Figure 3. Scurvy ✔ Explain the importance and application of epidemiology in the 12 ill patients who had all of the classic symptoms of scurvy were practice of medicine assigned different supplemental dietary interventions: ✔ Understand the basic vocabulary used in epidemiology → A quart of cider a day on an empty stomach → Two spoonfuls of vinegar three times a day on an empty I. EPIDEMIOLOGY stomach Study of the distribution and determinants of health-related states → Half-pint of sea water every day or events in human populations and the application of this study to → Lemons and oranges to eat on an empty stomach the prevention and control of health problems → Elixir recommended by a hospital surgeon Greek epi meaning “on, upon, or befall”, demos meaning “the → Combination of garlic, mustard seed, and horseradish people” and logos meaning “the study of” C. JOHN SNOW Epidemiologic investigations involve descriptive and analytic methods that draw on statistical techniques for describing data and evaluating hypotheses, biological principles, and causal theory. Disease is not randomly distributed throughout a population, but rather that groups differ in the frequency of various diseases. Knowledge of this uneven distribution can be used to investigate etiologic factors and to lay the groundwork for programs of prevention and control II. HISTORIC DEVELOPMENTS OF EPIDEMIOLOGY A. HIPPOCRATES (460-377 BC) Figure 4. John Snow Anesthesiologist for Queen Victoria of England Father of modern epidemiology Observed and recorded important factors related to the course of disease in cholera in the 1850s COMPARISON OF TWO WATER COMPANIES BY JOHN SNOW Figure 1. Hippocrates Father of medicine First epidemiologist Observations on how diseases affected populations and how disease spread Introduced terms like epidemic and endemic Figure 5. Spot map by John Snow Compared death rates from the disease to where the sufferers got their water. LE 1 Introduction to Epidemiology | Dulay, Dy, Echiverri, Elarco, TE | Dominice, Duquilla AVPAA | J. Nalugon PAGE 1 of 4 TRANS 1 Emman EPI | LE 1 Introduction to Epidemiology | Lissa Luz C. Calimag, MD, MPM-HSD, DFM The death rate was 71 per 10,000 in Southwark and Vauxhall Describing the natural history of disease households and 5 per 10,000 for Lambeth households. Monitoring diseases and other health-related events over time Lambeth was able to draw water free from London’s sewage. Evaluating the efficacy and effectiveness of prevention and Proved his hypothesis that contaminated water passing down the treatment programs sewers into the river, then being drawn from the river and Providing information that is useful in health planning and decision distributed through pipes into people’s homes, produced cholera making for establishing health programs with appropriate priorities throughout the community. Assisting in carrying out public health programs Being a resource person C. JOHN GRAUNT(1620-1674) Communicating public health information C. USES OF EPIDEMIOLOGY IN PUBLIC HEALTH POLICY AND INDIVIDUAL DECISION-MAKING 1. Assessment Identify who is at greatest risk for experiencing the public health problem Identify where the public health problem is greatest Identify when the public health problem is greatest Monitor potential exposures over time Monitor intervention-related health outcomes over time 2. Cause Identify the primary agents associated with disease, disorders, or conditions Figure 6. John Graunt Identify the mode of transmission A systematic recording of deaths commenced and was called the Combine laboratory evidence with epidemiologic findings “bills of mortality” 3. Clinical picture Systematically recorded ages, gender, who died, what killed them, Identify who is susceptible to the disease and where and when the deaths occurred. Identify the types of exposure capable of causing the disease Recorded how many persons died each year and the cause of Describe the pathologic changes that occur, the stage of death subclinical disease, and the expected length of this subclinical D. WILLIAM FARR (1807-1883) phase of the disease Identify the types of symptoms that characterize the disease Identify probable outcomes (recovery, disability, or death) associated with different levels of the disease 4. Evaluate Identify the efficacy of the public health program Measure the effectiveness (considering cost, availability of resources, and feasibility) of the public health program D. BEHAVIOR OF DISEASE IN THE COMMUNITY Table 2.Behavior of disease in the community Figure 7. William Farr occurrence of cases of an illness, specific Father of Modern Vital Statistics and Surveillance health-related behavior, or other International Classification of Diseases Epidemic health-related events clearly in excess of III. CONCEPTS AND TERMS IN EPIDEMIOLOGY normal expectancy in a community or A. BROAD CATEGORIES IN EPIDEMIOLOGY region Table 1. Descriptive vs. Analytic Epidemiology Outbreak epidemic that is confined to a localized Descriptive Analytic area Epidemiology Epidemiology Study of the amount/ Study of the determinants or Endemic ongoing, usual, or constant presence of a frequency & distribution of etiology of disease & related disease in a community or among a group disease, etc. in populations conditions of people B. DESCRIPTIVE EPIDEMIOLOGY Pandemic an epidemic affecting or attacking the AIM OF DESCRIPTIVE EPIDEMIOLOGY population of an extensive region, country, or continent Permit evaluation of trends in health and disease Provide a basis for planning, provision, and evaluation of health services Identify problems to be studied by analytic methods and suggest areas that may be fruitful for investigation 3 BASIC EPIDEMIOLOGIC QUESTIONS For almost all diseases/illnesses, three basic epidemiologic questions may be asked: Who develops the disease? → PERSON variables → Person – Age, Sex, Race and Ethnicity, Civil Status When does the disease occur? → TIME variables → Time - Seasonal/Cyclic, Secular, Epidemic Where does the disease occur? Figure 8. Differences among endemic, epidemic, and pandemic. → PLACE variables → Place – Global, National, Local ACTIVITIES IN EPIDEMIOLOGY Identifying risk factors for disease, injury, and death EPI Introduction to Epidemiology PAGE 2 of 4 EPI | LE 1 Introduction to Epidemiology | Lissa Luz C. Calimag, MD, MPM-HSD, DFM one host to another; mechanical or biological transmission Zoonosis an infectious organism in vertebrate animals (e.g., rabies virus, bacillus anthracis, Ebola virus, influenza virus) that can be transmitted to human through direct contact to a fomite, or a vector Reservoir Habitat (living or nonliving) in or on which an infectious agent lives, grows, multiplies, and on which it depends for its survival in natures Carrier a person which harbors the infective agent without showing signs of disease but is Figure 9. Scientific diagram of epidemic, endemic, and sporadic capable of transmitting the agent to other illness persons. E. CASE CONCEPTS IN EPIDEMIOLOGY H. MODES OF DISEASE TRANSMISSION Table 3.Case concepts in epidemiology Direct Transmission → the direct and immediate transfer of an infectious agent from a person in a population who has been one person to another. Requires physical contact between an Case identified as having a particular disease, infected host and a susceptible person, and the physical disorder, injury, or condition transfer of a pathogen. Case definition standard set of criteria ensures that cases → Ex: STD, perinatal mother-to-child, skin-to-skin are consistently diagnosed, regardless of Indirect Transmission where or when they were identified and → an agent is transferred or carried by some intermediate item, who diagnosed the case organism, means, or process to a susceptible host, resulting in Primary case the first disease case in the population disease. Index case the first disease case brought to the ▪ Air currents, dust particles, water, food, oral-fecal contact, attention of the epidemiologist and other mechanism ▪ vector-borne, vehicle-borne F. TRIANGLE OF EPIDEMIOLOGY Airborne Transmission - can be direct or indirect transmission 1. Traditional Triangle of Epidemiology I. SUMMARY Description in epidemiology begins with the assumption that diseases do not occur at random. Pioneers of Epidemiology Typically, three standard questions are posed to characterize the nonrandom distribution of a disease: → Who gets the disease? (person) → Where does the disease occur? (place) → When does the disease occur? (time) III. REVIEW QUESTIONS Figure 10. Traditional Triangle of Epidemiology 1. It is the study of the amount/ frequency & distribution of disease, etc. in populations 2. Advanced Triangle of Epidemiology a. Field Epidemiology b. Clinical epidemiology c. Descriptive epidemiology d. Analytical epidemiology 2. T/F: A disease is randomly distributed throughout a population. 3. A type of behavior of a disease with an ongoing, usual, or constant presence of a disease in a community or among a group of people. a. Endemic b. Epidemic c. Pandemic d. Outbreak 4. Identification: An object that can harbor an infectious agent and Figure 11. Advanced model of triangle of epidemiology is capable of being a means of transmission G. DISEASE TRANSMISSION CONCEPTS 5. Who created a spot map to investigate the cholera epidemic Table 4. Disease transmission concepts in London? a. John Graunt object that can harbor an infectious agent b. John Snow Fomite and is capable of being a means of c. James Lind transmission d. Hippocrates Vehicle nonliving intermediary such as fomite, ANS: food, or water that conveys the infectious 1. C agent from its reservoir to a susceptible 2. F host 3. A 4. Fomite 5. B Vector an invertebrate animal (e.g., tick, mite, mosquito, bloodsucking fly) that transmits by conveying the infectious agent form EPI Introduction to Epidemiology PAGE 3 of 4 EPI | LE 1 Introduction to Epidemiology | Lissa Luz C. Calimag, MD, MPM-HSD, DFM IV. Q&A 1. Is there a resource to check on-going epidemiological data? The Philippines’ public health departments such as DOH collects our epidemiological data. There are surveillance departments per region, per province, and on a national level. They collate all data but are not published. It can be requested from them—notifiable diseases like dengue and infectious diseases (HIV). For the available articles, it can be found in Google searches of DOH and WHO websites. 2. Are STDs solely classified under direct transmission? Yes, since there is no intermediary such as vectors, non-living things (air, solid objects). Only via direct transmission by person to person. On the other hand, examples of indirect transmission are vector-borne, vehicle-borne, those that are transmitted through air, water, or food, and oral-fecal contact. Exception: HIV from needles. They are classified under indirect transmission. 3. What’s the best way to differentiate fomite and vehicle? All fomites would be considered as vehicles but not all vehicles are considered as fomites Fomite - objects where infectious agents may reside on top, such as desk, cloths, bed sheets, door handle, spoon and fork Vehicle - includes air, water, food and are not called fomites V. REFERENCES Lumag, L.L.C., (2024) Introduction to Epidemiology [PPT slides] 2026 Transcript. Introduction to epidemiology Synchronous recording (Q&A): EPI Introduction to Epidemiology PAGE 4 of 4