Introduction to Epidemiology NURS 1113 PDF

Introduction to Epidemiology NURS 1113 – Unit 1 (Week 1) Mickelle Emanuel-Frith January 25,2024 Welcome to Epidemiology You are travelling to a country but you are only allowed to go to a place whose name begins with the first letter in your name. Say your name and tell me where you will be going. 2...

Introduction to Epidemiology NURS 1113 – Unit 1 (Week 1) Mickelle Emanuel-Frith January 25,2024 Welcome to Epidemiology You are travelling to a country but you are only allowed to go to a place whose name begins with the first letter in your name. Say your name and tell me where you will be going. 2 Ground rules Please be early for class, turn off the ringers on all cell phones, no talking during discussions or teaching session, submit all assignments at the specified time. No more than 5 minutes grace period for class. 3 4 Objectives At the end of the session students should be able to: 1. Define epidemiology and specific related terms 3. Discuss the history and developments (evolution) of epidemiology: Epidemiological era and paradigms *Sanitary *Infectious *Chronic 2. Explain basic terminologies and concepts of epidemiology 4. Explain core functions (surveillance, field investigations, analytic studies, evaluation and policy development), uses and goals of epidemiology 5 6 Epidemiology Dissection of the term, epidemiology (derived from Greek words) demos epi “on, upon” epidermis “people, population, man” demographics logos “Study of” sociology 7 Overview of Epidemiology http://www.youtube.com/watch?v=dmI987oM_6I This 20 minute video provides a good overview of what Epidemiology is about. You can view it as often as you would like to. Epi_Unit 1 VHWB-2023 8 Epidemiology Study of the distribution and determinants of healthrelated states or events in specified human populations and the application of study results to the promotion of health, and the prevention and control of health problems (Last, 1988) Study of the nature, cause, control and determinants of the frequency, and distribution of disease, disability and death in human population 9 a scientific discipline “The basic science of public health”. Originally, epidemiology was concerned with epidemic of communicable diseases then it was extended to non communicable diseases and other events e.g. injuries Concerned with frequency and pattern of health events in population (Descriptive epidemiology) Causes and risk factors that influence the occurrence of health related events, attempts to provide the why and how of such events by comparing groups (Analytic epidemiology) Epidemiology Study of the distribution and determinants of health-related states or events in specified human populations and the application of study results to the control of health problems Clinicians focus on treating and caring for individuals. Epidemiologists focus on the exposure, the potential for further spread in the community, and interventions to prevent cases or recurrences. Provides data for public health action Epidemiologists use descriptive and analytic epidemiology in “diagnosing” the health of a community and planning how to control and prevent diseases in the community 10 Epidemiology Basic science of public health Scientific method of disease investigation (causal reasoning based on developing and testing hypotheses) Provides data for directing public health action Relies on careful observation and use of valid comparison groups to determine if what is observed, differs from what is expected Draws from other scientific fields e.g. biostatistics, informatics, biology, social and behavioural sciences Epi_Unit 1 VHWB-2023 11 Epidemiology Involves characterizing the distribution of health status, diseases or other health problems in terms of: Age Gender Race Geography Religion, education, occupation, time, place, person... 12 Epidemiology Characterization allows for explanation of the distribution of a disease (or health-related problem) in relation to causal factors Cornerstone of public health research. Helps identify risk factors for disease and determine the most suitable treatment modalities 13 Miasma Theory Origin of epidemic due to a miasma (Greek for pollution), emanating from rotting organic matter Prior to 19th century, diseases were thought to be caused by “bad air” Some academics in the early nineteenth century extended the theory to other conditions as well, e.g. one could become obese by inhaling the odour of food “From inhaling the odour of beef the butcher's wife obtains her obesity.” Professor H Booth, writing in the Builder, July 1844 Obsolete medical theory 14 A Public Health Approach Surveillance Risk Factor Identification Intervention Evaluation Implementation 15 Source: CDC, nd History of Epidemiology 16 History of Epidemiology 17 History of Epidemiology 18 Spot Map of the Cholera Outbreak in London [Show video] 19 History of Epidemiology Group work - 5minutes Identify the contribution(s) that the following persons made to epidemiology: Florence Nightingale Anton van Leeuwenhook Edward Jenner Ignaz Semmelweis Louis Pasteur Assgn. - Read up on: Mary Mallon aka “Typhoid Mary” 20 Evolution of Epidemiology Chronic era Sanitary era (miasmic theory) Infectious era (Germ theory) (Risk factor theory) Early - mid 19th C 1900-1945 ? 1980 - 21 Evolution of Epidemiology Originally, epidemiology focused on epidemics of communicable diseases Expanded focus to include chronic diseases, injuries, violence, birth defects, maternal and child health, occupational health and environmental health 22 Evolution of Epidemiology 23 Evolution of Epidemiology 24 Epidemiological Era 25 Evolution of Epidemiology Sanitary era- (miasmic paradigm) -early to middle 19th Century. promoted the "miasmic" theory that disease was transmitted through the air, soil, and other elements. This era commenced during the 17th century and reached its apex by the middle of the 18th century. 26 Sanitary Era Its distant origins were the reaction to the various plagues that had scarred Europe, such as the Black Death. Miasmic epidemiology believed that disease was transmitted via the environment, and carried by the air, dust, or odors. Disease prevention and treatment included the use of strong sanitary measures, such as the advocacy of clean water supplies, fresh ventilation, and drainage, as well as the limitation of waste and contaminated water supply 27 Infectious Era Infectious Era (germ paradigm) - mid 1900s to 1945 advocated a theory of "germs," suggesting that one given agent was related to one specific disease. This was a change in direction; not so much from the advancements achieved through the sanitary movement, but it was a realization, through laboratory science, that many diseases were caused through infection. It was during this era, that public health nursing was born. MacDonald (2004) states that, although nursing still maintained the strong social conscience of the miasmic movement, gradually both nursing and medicine put a strict emphasis on single causative agents. From this, the disease prevention approach was born, which excluded social policy and health promotion. 28 Chronic Era The chronic disease era suggested a theory of influencing factors on the pathogenesis of a disease, including the risk and protective factors, and developed the new theory of a "web of causation." A web of causation is a complex interconnection of various proximate and remote factors that both promote and protect against disease (Brownson & Petitti, 2006; MacDonald, 2004). With infectious disease declining after World War II (WWII), much emphasis shifted to the study of chronic disease, which was becoming more prevalent. 29 Purposes of Epidemiology Explain the aetiology (cause) of a disease or group of diseases Determine consistency of data with proposed hypothesis Provide a basis for developing disease control and prevention measures for at-risk populations  prevention and control of disease 30 Purposes of Epidemiology Explain the aetiology (cause) of a disease or group of diseases Determine consistency of data with proposed hypothesis Provide a basis for developing disease control and prevention measures for atrisk populations  prevention and control of disease 31 Types of Epidemiology https://www.youtube.com/watch?v=6swwJ1Lg1LM 13 minutes preview only 32 Two Main Types of Epidemiology Descriptive Analytic Who? What? Where? When? Why / How? 33 Descriptive Epidemiology Examines distribution of disease in a population and the basic features of its distribution Who? (Person) Where? (Place) When? (Time) Age, Gender, Ethnicity, Genetic Geographic variation Calendar time predisposition, Marital status Presence of vectors or Time since an event Concurrent disease agents Lifestyle (diet, smoking, physical Climate activity, risk-taking behaviour) Population density Socioeconomic status (SES) Economic development Education Nutritional practices Occupation Medical practices Physiologic cycles Age (time since birth) Seasonality Temporal trends 34 Analytic Epidemiology Investigates hypothesis about cause of disease by studying the relationship between exposure and disease How was the population affected? Why was the population affected? 35 Core Functions Surveillance Field investigation Policy development Core Functions of Epidemiology Analytic studies Linkages Evaluation 36 Core Functions - Surveillance Ongoing, systematic collection, analysis and interpretation and dissemination of health data to help guide public health decision-making and action (“monitoring the pulse of a community”) Purpose – to depict ongoing patterns of disease occurrence and disease potential so that efficient and effective investigation, control and preventive measures can be taken (Surveillance provides information for action) 37 Surveillance Cycle 38 WHO STEPS Surveillance 39 Steps in a Surveillance System 40 Sources of Surveillance Data Morbidity and mortality reports Usually submitted by healthcare providers, infection control practitioners, laboratories (designated) Reports from investigations of individual cases and disease clusters Public health programme data e.g. immunization coverage, disease registers, health surveys 41 Core Functions - Field Investigation Public health department carries out prompt investigation of a surveillance case or cluster report May require coordinated effort of several persons to characterize the extent of an outbreak and identify its cause Objective of investigations may vary. Example it may be to: characterise the disease before deciding appropriate intervention method (“shoe leather epidemiology”) identify source or vehicle of infection – for control or elimination identify unreported or unrecognized persons who may continue the spread of the infection 42 Core Functions - Analytic Studies Analytic studies (looking at the “why and what”) employing more rigorous methods are sometimes necessary evaluate validity of hypotheses Analysis begins with describing the characteristics of the subject Hallmark of analytic studies is the use of valid comparison group Involves study design, methods, analysis, interpretation and dissemination of findings 43 Core Functions - Evaluation Process of determining the relevance, effectiveness, efficacy and impact of activities in relation to established goals, systematically and objectively Evaluation may focus on plans (formative evaluation), operations (process evaluation), impact (summative evaluation) and / or outcomes Effectiveness – ability of a programme to produce the intended or expected results in the field Efficacy – ability to produce results under ideal conditions Efficiency – ability of programme to produce intended results with minimum expenditure of time and resources 44 Core Functions - Linkages Field epidemiology usually has a multidisciplinary team; epidemiologists rarely work in isolation Many outbreaks cross geographical and jurisdictional boundaries. Co-investigators may be from locale Linkages are sustained through memorandum of understanding, informal networking, sharing of information for public health audiences and external stakeholders 45 Core Functions - Policy Development Based on study results, epidemiologists provide input, testimony and recommendations regarding: disease control strategies reportable disease regulation health care policy 46 Knowledge Check All of the following illustrate the purpose of epidemiology in public health, except A. identifying populations who are at risk for certain diseases. B. assessing the effectiveness of interventions. C. providing treatment for patients in clinical settings. D. determining the importance of causes of illness 47 Common uses of Epidemiology https://www.youtube.com/watch?v=89bvCS7do08 49 USES OF EPIDEMIOLOGY Study History of Health Events Determine cause-effect relationships Identify trends of a disease E.g. strep throat can cause rheumatic fever Study results useful in planning for health services and public health Allows for projections Identification and diagnostic process to establish existence of a condition or that a person has a specific disease 50 USES OF EPIDEMIOLOGY Identify syndromes Help establish and set criteria to define syndromes e.g. Down Syndrome, Sudden Infant Death Syndrome Determine causes and sources of diseases Findings allow for prevention, control and elimination of causes of disease, conditions, injuries, disabilities or death Syndrome - group of symptoms that collectively indicate or characterize a disease, psychological disorder, or other abnormal condition 51 USES OF EPIDEMIOLOGY Population / Community Individual Decisions Health Assessment Completing the Clinical Picture E.g. prevalence, incidence Studying a disease outbreak, epidemiologist depends on clinical physicians and lab scientists for proper diagnosis of individual patients. Epidemiologists will contribute to physicians' understanding of the clinical picture and natural history of disease Data used to determine whether services are available, accessible, effective and efficient Set policy and plan programmes Epidemiological information used in daily personal decisions e.g. to stop smoking, take stairs instead of elevator Decisions influenced by epidemiological risk assessment 52 Goals of Epidemiology Investigate and describe the distribution and magnitude of disease problems in human population Identify causation Provide data essential to planning, implementation and evaluation of health care 53 Goals of Epidemiology Provide foundation for developing public policy regarding disease prevention and health promotion 54 Solving Health Problems Step 1 - Step 1 Data collection Solving health problems Step 4 Action Action Step 1 - Surveillance; determine time, place, and person Step 2 Assessment Step 2 Inference Step 3 Hypothesis testing Step 3 Determine how and why Step 4 Intervention 55 Role of the Epidemiologist Outbreak investigation Study design Data collection and analysis Dissemination of findings 56 Functions of Epidemiologists include: Collect and analyze vital records (birth, death) Collect and analyse morbidity data Monitor diseases and other community health problems Investigate outbreaks leading to control or prevention of epidemics and other health related problems Design and implement research studies and health surveys 57 Functions of Epidemiologists include: Evaluate effectiveness of treatment methods Describe clinical course and natural history of disease Identify public health problems and measuring the extent of their distribution, frequency or effect on the public’s health Evaluate health programmes Provide data necessary for health planning or decision-making by health agency administrators or health policy makers 58 Summary Define epidemiology, distribution, frequency, pattern, determinants History and developments (evolution) of epidemiology Epidemiological era and paradigms Sanitary Infectious Chronic Two main types of epidemiology Core functions, uses and goals of epidemiology 59 References Bohning, D. (2011). Introduction to epidemiology. Franklin, J. (n.d.). Introduction to epidemiology. Retrieved from https://www.slideshare.net/jcfranklinnurse/epidemiology-65688547 60 TERMINOLOGIES Term Determinant Definition Causes and risk factors that influence the occurrence of a health event Distribution Frequency Frequency and pattern of health events in a population Number of health events (cases) in a population and its relationship to the size of the population. The resulting rates allows for comparison of occurrence of a disease across different populations Pattern Population Methods Occurrence of health-related events by time, place and person All people in a defined setting o rwith certain defined characteristics Process employed to describe frequency and distribution and scientific rationale used to determine causal relationship of disease distribution in populations E 61 TERMINOLOGIES Term Disease Infection Pathogen Pathogenesis Pathogenic Pathogenicity Syndrome Definition Pattern of response by living organism to invasion by foreign substance or injury which causes alternation of homeostasis (normal functioning) Entry and development or multiplication of an infectious agent in a host Organism capable of producing disease – e.g. viruses, bacteria, fungi, parasites Development, production or process of generating a disease Disease causing / producing Potential ability and strength of a pathogenic substance to cause disease e.g. tobacco smoking and lung cancer (see slide # 36) TERMINOLOGIES Term Infectivity Definition The proportion of exposed persons who become infected Invasiveness Virulence Toxin the proportion of clinically apparent cases that are severe or fatal Host Incubation period Carrier Time interval between entry of disease agent into the body and the initial manifestation of the disease Person who harbours a disease agent and is asymptomatic but can transmit the disease to others 63 TERMINOLOGIES Term Endemic Epidemic Pandemic Sporadic Zoonosis Definition Ongoing usual level (constant presence) of a disease or infectious agent within a given population or geographical area without importation from outside Outbreak or occurrence of a specific disease from a single source in a group population, community or geographical area in excess of normal expectation and derived from a common or propagated source An epidemic that spreads across many countries or the entire world Cases occur irregularly / haphazardly periodically (generally infrequently) Disease or infection naturally transmitted between vertebrate animals and human beings e.g. rabies 64 TERMINOLOGIES Term Incidence Prevalence Point prevalence Demography Population pyramid Definition The extent that persons within a population who do not have a disease develop the disease during a specific time period Number of persons within a population with a specific disease at a given point in time Number of cases of a disease existing in a group at that moment Study of births, deaths and migration and how they infpuence population changes Describes distribution by age 65 TERMINOLOGIES Term Morbidity Definition Events and factors associated with disease or disability Mortality Related to death 66 Terminologies Contagious – disease transmissible through contact Reservoir – habitat where an infectious agent lives, grows and multiplies Vector – usually an arthropod which transfers infectious agent from an infected person to a healthy person 67