Epidiology Flashcards
Emidiomology
The study of the distribution and determinants of health related states or events in specified populations
Frequency
How many cases compared to how many we usually have
Prevalence
Total number of cases in pipulation divided by total number of people in population x100
Incidence
Number of new cases in a given time period divided by total number of susceptible x100
Outbreak
When the number of cases rise above expected number
Epidemic
Local outbreak that becomes larger and then effects a wider area
Pandemics
Out of control and spreads to different continents
Endemic
Cases appear periodically but restricted in their geography
Epidemic
Out of control in local areas (cities in U.s)
Sporadic
Pop up sometimes
Critical community size
Endemic scan only persists within a population of a certain size
Mass action principle
spread of an infection will depend on how often vulnerable individuals come in contact with contagious individuals
Point source
Infectious agent comes from a single source, all victims exposed at that source
Common source
Single source but over a longer period
Propagated
Communicable from person to person, so spreads throughout population
Koch’s postulates
Isolate the microbe and grow it in the lab, study it’s properties
Inoculate a healthy animal with the microbe- does it stick?
Re-isolate the microbe and grow it in the lab, is it still the same one?
Determinants
The causes and other factors rhat influence the occurance of disease and other health related events
Mass action principle
Spread of an infection will depend on how often vulnerable individuals come in contact with contagious individuals
Point source
All individuals infected at that source (cholera in London)
Common source
Single source over king period of time (typhoid Mary)
Propagated
Communicable form person to person so spreads throughout population
Eg SARS
Descriptive epidemiology
The use of surveillance date to formulate hypotheses about the cause of the disease and possible risk factors involved
Types of descriptive epidiomology
Observational/descriptive
Cohort study
Case control study
Intervention study
Follows a population of participates after giving them an intervention of some kind
Key is to determine the outcome of the intervention
Randomized controlled trails like the gold stands
Analytical epidiomology studies require information to
Know where to look
Know what to control for
Develop viable hypotheses
Three essential characteristics that we look for in descriptive studies are
Person
Place
Time
Case-series
Groups of people with a similar diagnoses or who have received the same clinical treatment are investigated
Ecological studies
Groups of people or animals investigated
Comparing health of people in different places and times
Cross-sectional study
Analyzing data from the population or a representative subset at a specific point in time
Example: in December of 2018 at BU what proportion of students had the flue
Cohort study
Follows a population of participants over a period of time
Proportion of disease (exposed) divided by proportion of disease (unexposed) equals relative risk
Case control study
Analsyzes date from people with disease to people without
Sequelae
A condition which is the consequence of a previous disease or injury
Sensitivity
The ability of a test to correctly indentify those with the disease (true positive rate)
Specificity
The ability of the rest to correctly identify those without the disease (true negative rate)
Lab based tests
Slow more accurate
Cell culture
Susceptibility test
Point of care tests
Faster, generally less accurate
Blood glucose
Drug sceeens
Antibody tests
Polymerase chain reaction
Multiple sets of DNA primers can identify individual genes from a pathogen for more specific typing
Useful for pathogens that are hard to grow or slow to grow
Useful for getting results more quickly than growth based test allow
Immunological tests are
Much faster than other types of diagnostic testing
