1: History & Scope of Epidemiology Flashcards
Epidemiology derived from Greek words:
epi- on, upon, or befall
demos- the people
logos- the study
The study of what befalls the population
Definition of Epidemiology
concerned with the distribution and determinants of health and diseases, morbidity, injuries, disability and mortality in populations
Define Determinants
factors or events that are capable of bringing about a change in health. The search for causes and other factors of health-related states or events
Examples of Determinants
Health-related states or events-
Search for Determinants-
Health-related states or events: Disease states (biologic and chemical agents) and Conditions associated with Health (physical activity, nutrition, environmental poisoning, seat belt use, use of health services, etc)
Search for Determinants: Anthrax outbreak, Hantavirus outbreak, etc.
Define Distribution
study of frequency and pattern of health events in the population
Define Distribution Frequency
number, and number relation to the population
Define Distribution Pattern
the health-related state or event by person, place, and time characteristics
Disease Distribution Examples
- CHD death rates and stroker higher in African-Americans than other races
- HIV rates in UT from 2000-2010 40x higher in African-born immigrants than Caucasian males
Define Morbidity
designates illness
Define Mortality
refers to deaths that occur in a population or other group
Aims and Levels of Epidemiology
- DESCRIBE the health status of populations
- EXPLAIN the etiology of disease
- PREDICT the occurrence of disease
- CONTROL the occurrence of disease (intervention/prevention)
Central activity of epidemiology
quantification
Epidemic
a spike in cases from what you would expect to see
Endemic
what you would expect to see in a population
Infectious Disease Epidemic qualifications
- a single case of a long absent communicable disease
- first invasion of a communicable disease
- two cases of such a disease associated in time and place
Infectious Disease Triangle
Center: TIME
Top: ENVIRONMENT
Left: HOST
Right: AGENT
Pandemic
an epidemic on a worldwide scale. large numbers of persons may be affected and a disease may cross international borders
Pandemic example
flu, HIV
ascertainment of epidemics
surveillance and epidemic threshold
define surveillance
- The systematic collection of data pertaining to the occurrence of specific diseases.
- analysis and interpretation of these data
- dissemination of disease-related information
cancer incidence
the number of people who get cancer
Epidemic Threshold
The minimum number of cases (or deaths) that would support the conclusion that an epidemic was underway. may adjust based on what is expected
historical epidemiological antecedents
- environment and disease
- the black death
- use of mortality counts
- smallpox vaccination
- natural experiments
- identification of specific agents of disease
- 1918 influenza pandemic
Hippocrates
- Father of medicine and first epidemiologist
- suggested disease might be associated with the physical environment (malaria and swampy water)
- represented a movement away from supernatural explanations of disease causation
- Environment and Disease
Hippocrates
- The Black Death
1346-1352. claimed 1/4-1/3 of population of Europe
- Use of Mortality Counts
John Graunt
John Graunt
- Recorded how many persons per year died of what kind of event or disease
- Developed and calculated life tables and life expectancy
- Divided deaths into two types of causes: acute & chronic
- Smallpox Vaccination
Edward Jenner: invented vaccination for smallpox
- Use of Natural Experiments
John Snow: two water companies supplied water. when one moved its source of water to a less polluted portion of the river, Snow noted how that effected the next cholera outbreak
John Snow
- 1st current day epidemiologist
- English physician and anesthesiologist
- linked cholera epidemic to contaminated water supplies
- used spot map of cases and tabulation of fatal attacks and deaths
Natural Experiment definition
The epidemiologist does not manipulate a risk factor but rather observes the changes in an outcome as the result of a naturally occurring situation.
- Identification of specific agents of disease
Ignaz Semmelweis, William Farr, and Robert Koch
Ignaz Semmelweis
- “savior of mothers”
- early pioneer of antiseptic procedures
Examples of Contemporary Natural Experiments
Seat Belts Law, Tobacco Tax
William Farr
- provided foundation for classification of diseases
- examined linkage between mortality rates and population density
Robert Koch
-established the Germ Theory
Koch’s Postulates
- microorganism must be observed in every case of the disease
- microorganism must be isolated and grown in pure culture
- pure culture must, when inoculated into a susceptible animal, reproduce the disease
- microorganism must be observed in, and recovered from, diseased animal
1918 Influenza Pandemic
- killed 50-100 million worldwide
- 2.5% case-fatality rate (vs 0.1% for other flue)
- deaths most frequent among age 20-40
recent applications of epidemiology
- Framingham Heart Study (since 1948, investigates coronary heart disease risk factors)
- Smoking and lung cancer (Doll and Peto’s study of British doctors’ smoking)
- AIDS
- chemical spills
- breast cancer screening
- secondhand smoke
Applications of Epidemiology (6 broad categories)
- Infectious Diseases
- Environmental Health
- Chronic Diseases
- Lifestyle and Health Promotion
- Psychiatric and Social Epidemiology
- Molecular and Genetic Epidemiology
