Epidemiology (I) Basics Flashcards
What are the five objectives of epidemiology?
To identify the etiology, extent, natural history and prognosis, and treatment options related to disease(s) in order to develop public policy
What is the purpose of an epidemiological study of disease etiology?
To reduce morbidity and mortality by identifying risk factors and causative agents
What is the purpose of an epidemiological study of the extent of disease?
Used for health systems planning and prioritizing health programs based on disease burden
What is the purpose of an epidemiological study of disease natural history and prognosis?
To answer patient questions about survival and the severity of a disease; to provide information about screening; to provide a baseline to compare future treatments
What is primary prevention?
Preventing the onset of disease
What is secondary prevention?
Screening for asymptomatic (but diseased) individuals
What is tertiary prevention?
Disease treatment
What is first-step epidemiology?
Descriptive epidemiology
What is second-step epidemiology?
Analytic epidemiology
What is the main question in descriptive epidemiology?
Is there an association (correlation) between two or more factors? (hypothesis generating)
What is the main question in analytic epidemiology?
Is the identified association causal? (hypothesis testing)
What is experimental epidemiology?
Clinical trials – Evaluation of the effectiveness of an intervention and/or preventative and therapeutic programs
What are the three corners of the epidemiologic triangle?
Host, environment, agent
What is in the center of the epidemiologic triangle?
A vector or vehicle
Are vectors alive or dead?
Alive (organisms)
Are vehicles alive or dead?
Dead (inanimate objects or substances)
What are some categories of disease-causing agents?
Biological, chemical, physical, nutritional
What is direct disease transmission?
Human-to-human
What is indirect disease transmission?
A common source (vehicle) or vector transmits the disease
What is it called when an individual is infected but shows no signs or symptoms?
Subclinical infection
What is it called when a person is chronically infected with continued low-grade survival and multiplication of the agent (e.g. HIV or typhoid)?
Persistent infection
What is it called when a person is infected with an agent with no active multiplication of the agent (as when viral nucleic acid is integrated into the nucleus of a cell as a provirus)?
Latent infection
In contrast with a persistent infection, only the genetic message is present in the host, not viable organisms
What is a carrier?
A host infected with an organism that is asymptomatic but capable of transmitting disease (e.g. Hepatitis B or HHSV)
What is the period from exposure to symptoms when the organism is actively replicating?
Incubation period


