General Principles of EPI Flashcards
Describe EPI
Study of the
Frequency
distribution
cause
control of disease in populations
Understand the relationship between host, environment and organism
Purpose of EPI
Person, place, and natural history
Define Risk
Probability or likelihood of an event occuring
Define Risk Factor
Characteristic, behavior, experience that increases the probability of developing a negative health status (disease or infection).
Epidemiology, unlike clinical medicine, is population based and is useful for describing health-related phenomena in groups of people.
Epi triangle model of disease causation
Host: human or other animal
Environment: external factors associated with the host
Agent: bacteria, virus, fungus, protozoan, helminth or prion
Wheel model
Hub: host or human with an inner core of genetic information.
Surrounding environment divided into three parts: social, biological, physical.
Web Model of causation
aims to capture the more complex interactions between biological (host), environmental, and social factors contributing to disease.
Emphasizes social and political aspects of human life.
What is an association and the three types?
As one variable changes there is a resultant change in the quantity or quality of another variable.
Artifactual (spurious) (chance or random error)- may be result of study design-> systematic error or bias.
Indirect or noncausal-> may result from mixing of effects between the exposure, the disease, and a third factor (confounding variable)
Casual
What is a confounding variable?
Related to both the potential cause of a disease and the disease itself.
Scientific criteria for CAUSATION (Koch) 4 points
- organism must always be found with the disease, in accordance with the clinical stage observed
- the organism must then be grown in pure culture from a diseased host
- the same disease must be reproduced when a healthy susceptible host is innoculated
- the organism must be recovered from the experimentally infected host.
Hill’s Criteria for Caustion
Applying the criteria for causality is not as straightforward when the etiology is not clear
- Strength of association
- Consistency
- Specificity
- Temporality
- Biological Gradient
- Biologically Plausible
- Coherence
- Experimental Knowledge
- Analogy
HAI prevention strategies are wide ranging and depend on the disease in question and what information is available to the practitioner.
Primary, secondary and tertiary prevention
Primary prevention strategies to prevent the occurrence of disease include: barrier precautions, immunizations of HCP, cleaning, sterilizing, and disinfecting.
Define incidence
Number of new cases of a given disease in a given time period
Define prevalence
number of existent cases of a given disease at a given time.
Endemic
usual incidence of a given disease within a geographical area during a specified time period
Epidemic
an excess over the expected incidence within a geographical area during a specified time period
Pandemic
Epidemic spread over a wide geographic area, across countries or continents
Outbreak
A group of people with the same disease who are epidemiologically linked
Cluster
a group of persons with a given disease occurring in the same space and time, but which have not been epidemiologically linked. If linked, by EPI may become an outbreak.
Zoonosis
A disease transmitted from animals to humans
Enzootic
Usual presence of disease among animals within a geographical area. Animals may serve as a reservoir.
Epizootic
excess of disease than in expected in the animal population
Reservoir
Place where agent can survive but may or may not reproduce.
Eg. Pseudomonas (gram negative, arerobic rod) in nebulizers
Hep b on surface of hemodialysis machine