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Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
A. W. Selassie 1
Manya Magnus, PhD, MPH 1
Lecture 1Introduction to Methods in Infectious
Disease Epidemiology
Manya Magnus, PhD, MPH 2
Slides developed by Manya Magnus, PhD, MPH
based on and for use in conjunction with her text,
Essentials of Infectious Disease Epidemiology
Jones and Bartlett, Inc.
Adapted to fit course curriculum of BMTRY 713 (Infectious Disease Epidemiology)
A. W. Selassie
Manya Magnus, PhD, MPH 3
Outline
• Welcome to the course
• Objectives
• Syllabus– Policies and procedures
– Evaluation
– Texts and resources
• Why learn methods in infectious disease epidemiology?
Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
A. W. Selassie 2
Manya Magnus, PhD, MPH 4
Welcome
• Welcome to the course– Introductions
• Professor
–Professor experience, research emphases
• Students
–Background, interest in course material
– What this course is and what it is not
Manya Magnus, PhD, MPH 5
Course objectives (1)• At the completion of this course, the student will
be able to:
– Apply epidemiologic methods to the context of infectious disease
– Critically evaluate infectious disease literature
– Understand study designs & procedures for evaluating infectious diseases in a variety of settings
– Confidently work in a public health or research setting focused on infectious disease
Manya Magnus, PhD, MPH 6
Course objectives (2)– Delineate steps in conducting the following types
of studies:• Descriptive studies• Outbreak investigations• Experimental designs • Cohort studies
–Prospective (concurrent)–Retrospective (non-concurrent)–Ambidirectional
• Case-control• Cross-sectional
Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
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Syllabus (1)
• Course logistics (when, where, office hours, etc.)
• Professor-specific policies and procedures
• Textbooks and resources
Manya Magnus, PhD, MPH 8
Syllabus (2)
• Course evaluation
Manya Magnus, PhD, MPH 9
Lecture objectives
• By the end of this lecture, you will be able to – Discuss importance of epidemiology methods
in the study of infectious disease
– Define methodology
– List at least four reasons why epidemiology methods are necessary
Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
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Why learn methods? (1)• “It is time to close the book on infectious diseases,
declare the war against pestilence won, and shift national resources to such chronic problems as cancer and heart disease.”
~U.S. Surgeon General William H. Stewart, 1967
• “We are standing on the brink of a global crisis in infectious diseases. No country is safe from them. No country can any longer afford to ignore their threat.”
~Hiroshi Nakajima, Director-General of the World Health Organization, 1996
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Why learn methods? (2)• Importance of learning methods in addition to
clinical infectious disease epidemiology
– Following decades of decline in infectious diseases, now increasing morbidity and mortality—eroding successes of the past decades
– Need public health professionals who understand basic principles of studyingdiseases—including newly emerging or re-emerging ones—in addition to knowledge about existing organisms
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Why learn methods? (3)
Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
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Ten Great Public Health Achievements of the
20th Century, and Remaining Challenges
Source (unless otherwise attributed): adapted from Centers for Disease Control and Preventionhttp://www.phppo.cdc.gov/phtn/tenachievements/default.asp
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The 20th Century in the U.S. has seen:
• A decrease in death rates, especially infant and child mortality
• A corresponding increase in life expectancy• A shift away from infectious diseases and
toward chronic diseases• This reflects the “Epidemiologic Transition,”
which is occurring worldwide in developing countries.
Manya Magnus, PhD, MPH 15
Leading Causes of Death, U.S., 1900 vs. 2000
19001- Influenza & Pneumonia2- Tuberculosis3- Heart Disease4- Stroke5- Diarrhea/Enteritis6- Nephritis7- Cancer8- Unintentional Injury9- Diphtheria10- Diseases of Early
Infancy
20001- Heart Disease2- Cancer3- Stroke4- COPD5- Unintentional Injury6- Diabetes 7- Influenza & Pneum.8- Alzheimer’s Disease9- Nephritis10- Septicemia
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What changes have contributed to decreased morbidity and
mortality?
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Control of InfectiousDiseases
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For example, control of pneumonia, malaria, polio,
smallpox, and mumps
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Pneumonia and Influenza mortality rates by age during certain epidemic years.
(Centers for Disease Control, 1972)
Age
Dea
ths
per
100
,000
Po
pu
lati
on
0
500
1000
1500
2000
0 10 20 30 40 50 60 70 80
1892191819361957
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Malaria: Once endemic throughout the southeastern United States, malaria was brought under control by the late 1940s. But this successful effort has not taken place globally.
Photo by Jim Gathany,Courtesy of CDC
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Smallpox EradicatedWorldwide
1980
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Poliomyelitis cases reduced by 90% since 1988.
Global eradication is now in sight
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Certain advances have contributed to this public health achievement (and are
achievements in their own right):
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Improved Sanitation
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VACCINATIONS
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Safer andHealthierFoods
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Characteristics and sources of foodborne diseases have been identified throughout the 20th century. Control of many diseases has been brought about through technology and safer food-handling procedures, including:
• Hand washing • Better sanitation• Refrigeration • Pasteurization• Pesticide application • Safer food processing• Reduction of • Better animal care
foodborne pathogens and feeding • Improved surveillance
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January 6, 2016
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Safer Workplaces
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MotorVehicleSafety
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ImprovedOccupant Protection:
Approximately 85,000 Americanlives have been saved because of seat belts.
Photo by Jim Gathany; Courtesy of CDC
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Changes in Societal Norms and Individual Behavior:
Since 1987, communityawareness and driving-while-intoxicated regulations have helped reduce alcohol related traffic fatalities by 32% in the U.S.
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Decline in Deaths from Coronary Heart Disease and Stroke
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Healthier Mothersand Babies
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Photo by Troy Hall; Courtesy of CDC
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Recognition of Tobacco Use as a Health Hazard
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Family Planning
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Fluoridation of Drinking Water
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But the infectious disease book most certainly is not closed. We have increasing challenges, and threats to public health that we
cannot yet anticipate.
Knowledge of how to understand and study infectious disease is
needed.
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New modes of disease transmission have been
created by progress:
Progress ProblemVentilation systems Legionnaires’ DiseaseBlood transfusion HIV, Hepatitis CCentrally processed food Salmonella, E. coli 0157:H7Air travel Rapid disease spreadEconomic development & Exposure to new vectors &
tourism diseases Suburbanization Lyme disease/rabies Antimicrobial agents Drug-resistant organisms Modern medical treatments Opportunistic infections
(e.g. bone marrow transplant,chemotherapy, renal dialysis)
Source: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4829a1.htm#tabbox3
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What is epidemiology? (1)The study of how disease is distributed in
populations, and of the factors that
influence this distribution
Derived from: “epi” (upon)
+ “demo” (people)
+ “logos” (the study of)
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What is epidemiology? (2)
The study of the distribution and determinants of disease in human populations and the
application of this study to control health problems
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Purposes of epidemiology
• Study the natural history and prognosis of disease
• Determine the extent of disease in a population
• Identify the etiology (causes, risk factors) of disease
• Evaluate effectiveness of preventive measures, therapeutic measures, and modes of health care delivery
• Provide basis for establishing public policy and regulatory decisions
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Ultimate Goal: identify means to prevent disease
• Primary Prevention - actions taken to prevent the development of disease among persons who do not have the disease in question
• Secondary Prevention - actions taken among people who have already developed a disease to improve their prognosis; refers to early detection (screening) and early intervention
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Differences between basic, clinical, and public health science research:
Basic Clinical Public Health
What/Who is Studied
cells, tissue, animals
sick patients populations
Research
Goalsdisease
mechanisms
improve diagnoses
and treatments
prevention, health promotion
Examplestoxicology,
immunology
internal medicine,
pediatrics, etc.
epidemiology, environmental
health sciences
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Infectious disease epidemiology:how it differs from other applications (1)
• Epidemiology as a “toolkit” of methods
– Same methodological approach used to understand relationships between exposures and outcomes
• Methods are design approaches that we use to study something and examine relationships—how we do something
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Infectious disease epidemiology:how it differs from other applications (1)
• As many conditions and problems there are in public health, there are as many application of epidemiology to them. Some examples:
• Cancer• Social and behavioral concerns (social epidemiology):
smoking, obesity, drug use, etc.• Chronic diseases• Cardiovascular disease• Nutrition• Environmental and occupational• And many, many more
• Same methods used for each of these, with “cultural” changes and modifications to toolkit based on need of specific types of outcomes of interest
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Infectious disease epidemiology:how it differs from other applications (2)
• What makes infectious disease different from other arenas of health concerns?– Multiple infectious agents– Heterogeneous infectious agents
• Not only different types of organisms—viruses, bacteria, fungi, parasites, etc.—but within each type, still further types and categories. Each one must be studied and treated uniquely
– There are organisms which cause acute, chronic, or both acute and chronic diseases
– Symptomatic and asymptomatic diseases– Multiple modes of transmission– Dynamic, not static– Infectious agents constantly emerging, re-emerging,
evolving (e.g., resistant strains)
What Lies Ahead
• DNA and the human genome• Genomics and proteomics• Genetically-modified foods
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Assignment for next week:
Infectious Disease Epidemiology (BMTRY 713) Lecture 1
January 6, 2016
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Thank you for your attention
Questions?