Micro Bio Unit 3 Flashcards
chapter 16
Prevalence vs Incidents
Incidence is the number of new cases (morbidity or mortality), usually expressed as a proportion, during a specified time period;
Prevalence is the total number affected in the population, again usually expressed as a proportion.
Morbidity vs Mortality
Morbidity means being in a state of illness, whereas
Mortality refers to death
Sporadic Diseases
occur only rarely and largely without a geographic focus.
endemic diseases
occur at a constant (and often low) level within a population.
epidemic and pandemic diseases
occur when an outbreak occurs on a significantly larger than expected level, either locally ( epidemic )or globally ( pandemic) respectively
Koch’s postulates
in the late 1800s. Koch developed four criteria, now known as Koch’s postulates, which had to be met in order to positively link a disease with a pathogenic microbe. As originally stated, the four criteria are: (1) The microorganism must be found in diseased but not healthy individuals; (2) The microorganism must be cultured from the diseased individual; (3) Inoculation of a healthy individual with the cultured microorganism must recapitulated the disease; and finally (4) The microorganism must be re-isolated from the inoculated, diseased individual and matched to the original microorganism.
Explain the relationship between epidemiology and public health
Epidemiology is the science underlying public health.
Study of distribution, timing, and transmission of disease
Concerned with discovering etiology (causative agent)
John Snow
British physician and father of epidemiology.
Detailed mapping of cholera incidence led to the discovery of the contaminated water pump on Broad street (red square) responsible for the 1854 cholera epidemic.
Contemporaries did not believe him, “malaria” was still the scientific paradigm
Florence Nightingale
reported on the data she collected as a nurse in the Crimean War.
Nightingale’s diagram shows the number of fatalities in soldiers by month of the conflict from various causes. The total number dead in a particular month is equal to the area of the wedge for that month. The colored sections of the wedge represent different causes of death: wounds (pink), preventable infectious diseases (gray), and all other causes (brown).
Joseph Lister
Initiated the use of a carbolic acid (phenol) during surgeries
Experimental
Koch’s postulates require experimental interventions to determine the causative agent for a disease. Unlike observational studies, experimental studies can provide strong evidence supporting cause because other factors are typically held constant when the researcher manipulates the subject. The outcomes for one group receiving the treatment are compared to outcomes for a group that does not receive the treatment but is treated the same in every other way. For
Analytical
Analytical epidemiology employs carefully selected groups of individuals in an attempt to more convincingly evaluate hypotheses about potential causes for a disease outbreak. The selection of cases is generally made at random, so the results are not biased because of some common characteristic of the study participants. Analytical studies may gather their data by going back in time (retrospective studies), or as events unfold forward in time (prospective studies).
descriptive
Descriptive epidemiology gathers information about a disease outbreak, the affected individuals, and how the disease has spread over time in an exploratory stage of study. This type of study will involve interviews with patients, their contacts, and their family members; examination of samples and medical records; and even histories of food and beverages consumed. Such a study might be conducted while the outbreak is still occurring. Descriptive studies might form the basis for developing a hypothesis of causation that could be tested by more rigorous observational and experimental studies.
- Describe the different types of disease reservoirs
Humans
Animals
Enviroment
Plague Vector
Flea
