1) What are the root words of epidemiology and what do they mean?
2) What is epidemiology?
1) epi meaning “on or upon”, demos meaning “people” and logos meaning “the study of”
2)The study of the distribution and the determinants of health related events in a specified population, and the application of this study to the control of health problems.
What are the major areas of epi and describe each?
- Frequency - Number of events/ rate or risk of disease
- Quantification- central activity counting cases
Distribution- occurrence of events (i.e., time, place, demographics)
Determinants - factors causing health event how and why by comparing groups
Application - provides data to direct public health action
Epidemiology is often referred to as _______.
because it is concerned with groups and not individuals.
Epidemiology translate data into _____ and ____ into ________.
- Blank One: information
- Blank Two: information
- Blank Three: Action
List at least five fields that epidemiology relies on.
- 1- Biostatistics
- 3- Clinical Medicine
- 5- Pathology
Define Morbidity and Mortality
- Morbidity- health illness
- Mortality - death
What are the four aims of Epi?
- 1- Describe- health status of population
- 2- Explain - etiology of disease
- 3- Predict - the occurrence of disease
- 4- Control - the occurrence of disease
List at least five areas that epi investigates.
- 1. Chronic illness
- 2. Injury
- 3. Communicable/Infectious Diseases
- 4. Disability
- 5. Neonatal
- 6. Drug Addition
- 7. Suicide
The occurrence in a community or region of cases of an illness ( or an outbreak) clearly in excess of expectancy
Relative to usual frequency of the disease
Under what conditions can you classify the occurrence of an epidemic?
1 - A single case of a long absence communicable disease
2- First invasion of a communicable disease
3- Two cases of a communicable disease associated in time and place
The normal rate of disease. The expected levels seen over time. The background level of disease.
An epidemic on a worldwide scale. Example the flu pandemic.
How do health officials determine epidemics?
Surveillance and an epidemic threshold
What is surveillance?
A systemic method of collecting data relating to a disease occurrence. Analysis and interpretation of the data and dissemination of disease related information
What is an epidemic threshold?
The minimum number of cases/deaths that indicates an epidemic occurrence.
What is a holoendemic?
A disease that basically all of the population acquires, usually during childhood. Controlled by vaccinations.
The number of new cases that occur during a certain timeframe.
Define Cumulative Incidence.
- The rate of development of disease over time.
- Number of new cases X TimePopulation at risk
Time= the period the cases occur
What is the attack rate?
Alternative form of incidence. Used when disease occur of a short period of time.
Not true rate because time unknown
- AR = ill X 100 (during time period) ill + well
Number of existing cases (TOTAL) at a certain time
What is the relationship between prevalence and incidence?
Prevalence (P) of disease is proportional to the incidence rate (I) times the Duration (D) of the disease.
True or False.
If the duration of the disease is short the prevalence becomes similar to incidence.
Example common cold
True or False
If duration of disease is long and incidence is high, prevalence increases greatly relative to incidence.
- If duration of disease is long and incidence is
- low, prevalence increase greatly relative to incidence.
Example chronic diseases
Explain the basic triangle model.
This model illustrates the interaction between the host, agent, and environment.
Explain the advanced triangle.
The interactions between the population, causative factors, and social/physical environment.
Explain the wheel model.
- Inner most circle - intrinsic
- Middle circle - host
- Outer most circle - extrinsic
Explain the single agent- single disease model.
For a disease there is only one causing factor/agent.
Example: Hiv(agent) -> AIDS (disease)
Explain multifactorial etiology.
Multiple factors cause a disease.
- Factors: diet, physical activity, stress, smoking, high blood pressure
Disease: Heart Disease
Explain the web of causation.
Multiple factors can cause multiple diseases.
- Diet > Cancer, Stroke, Heart Disease
- Smoking > Heart Disease, Stroke, Cancer
- Stress > Heart Disease, Stroke
Explain the Holistic Model.
- All of this elements affect the host
- Host > biological, environment, life style, and health care system
What are the portals of entry for each.
- respiratory: particulates, aerosols
- oral/gastrointestinal: ingestion
- reproductive: STIs anus, vagina, penis
- skin: cut/follicles/absorb
- intravenous: drugs contaminated blood products
- auditory canal:ear infections
- transplacental: HIV, chemicals, drugs
- cardiovascular: plaque
- conjunctival: eye
How do agents cause disease?
- 1. Interferes with normal body function (cancer)
- 2. Cause reaction (inflammation)
- 3. Destory tissue/organ function (ie stroke, AIDS)
What are the measures of disease severity?
- Inapparent: no signs or symptoms
- Mild: signs or symptoms (S&S) but able to fucntion normally
- Moderate:S&S, not functioning normally, but not under medical care
- Severe: S&S, not functioning, under medical care
- Fatal: RHC respirations have ceased
the capacity of the agent to enter and multiply in a susceptible host an thus produce infection or disease
- Secondary Attack Rate
- new cases/ susceptible exposures
capacity of the agent to cause disease in the infected host.
the severity of the disease, the ability to cause severe or fatal cases if the person becomes ill. One measure of virulence is the proportion of the total cases that are severe.
Explain Case Fatality.
ability to cause death if the person becomes ill.
ability of agent to induce antibody production in the host. Refers to an infectious agent ability to produce a specific immunity and protect against re-infection.
ability of agent to induce antibody production in the host. A related term immunogencity which refers to an infectious agents ability to produce a specific immunity.
The ability of the agent to survive in adverse conditions-environmental, medications, etc. Can also apply to the host
capacity of the agent to produce a toxin or posion. Pathologic effects for agents such as botulims, E. coli, result form the toxin produced by the micro-organism rather than the micro-organism itself.
List and explain body defenses.
Barriers and Secretations: skin, stomach acidic, mucus
Natural Flora: normal microbial flora provides checks and balances
Inflammatory Response: Swelling/edema, elevated temperature
Reticuloendothelial system (RES): clears micro-organisms from the blood. lymph systems