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78 Cards in this Set
- Front
- Back
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infectivity
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1. the ability of an agent to invade and multiply in a host
2. the ability of an agent to produce infection |
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pathogenicity
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1. the ability to produce clinically apparent illness
2. the percentage of infections that result in illness |
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virulence
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1. the proportion of clinical cases resulting in sever clinical manifestation
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immunogenicity
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the infection’s ability to produce specific immunity
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how do we measure virulence
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case fatality rate (CFR) is one measure of virulence (% of cases that die)
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what is a reservoir
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living organism or inanimate matter in which an infectious agent normally lives and multiples
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what is the difference between direct contact and indirect contract
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direct: straight from one person with the disease to another.
indirect: via vector, vehicle, or airborne |
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what is an example of a vector
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malaria via mosquito bite
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what is an example of a vehicle
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EKC via a tonometer probe
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how is TB transmitted
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via coughing and sneezing
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what is risk of active TB
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1. high density urban population areas
2. genetic/health factors 3. presence of HIV or AIDS 4. high homelessness population 5. GENDER (MEN 2X LIKELY) |
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how is TB transmitted
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1. inhalation of aerosolized bacilli
2. dark, poorly ventilated areas |
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what is the difference between cluster and outbreak
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1. cluster: aggregation of cases over a period of time in a place
2. outbreak: a cluster that is unexpected, synonymous with epidemic |
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what is the first step in investigation
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CONFIRM THE EXISTENCE OF AN OUTBREAK
*last step: report findings |
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what changed as a result of the outbreak of Legionnaries
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A/C standards were changed to require more stringent cleaning and hygiene of large scale A/C system
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who was infected in the legionaries outbreak?
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1. attendees of the american legions conventions (older men)
2. 221 people infected and 34 deaths (CFR= 15%) |
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why was the CDC involved in the legionaries outbreak
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an epidemic of swine flu had been predicted
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what was the basic story behind the hanta virus
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1. three otherwise healthy, young, athletic Native Americans died suddenly of respiratory illness
2. 19 cases/12 deaths |
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why was the CDC involved in the hanta virus outbreak
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1. the new mexico dept. of health and IHS did not have the resources to perform the task
2. added new possible causes for the illness |
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how did they eventually find out the cause of the hanta virus? what was the cause?
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1. the investigators wisely decided to consult with Tribal Elders
2. abnormally large Pinon nut harvest produce a abnormally large deer mice population, carrying the virus 3. virus is inhaled through deer mice feces |
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what is the prevalence of myopia
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myopia increases in childhood each year...25% at age 18
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how does % of Rxs for hyperopia change with age
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1. increase in hyperopic prescription with aging
prevalence of vision disorder 15%...age 5 30%...age 20 40%...age 40 100%...age 45 |
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what is the correlation between eye disease and aging? prevalence?
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INCREASE with AGE
prevalence: 5% of US population |
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top 3 leading causes of blindness?
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1. cataracts
2. POAG 3. ARMD |
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what are the risk factors for glaucoma
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1. age
2. race/ethnicity 3. family history 4. increased IOP 5. increase C/D ratio 6. asymmetric cupping 7. nerve fiber layer loss 8. diabetes 9. systemic hypertension |
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prevalence of glaucoma in US? what is the most common form?
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1. 2% of the age of 40
2. POAG...account for 70% of adult glaucoma |
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is there a good screening test for glaucoma
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NO
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what is the difference between descriptive and explanatory studies
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1. descriptive: gather and report data, no hypothesis to test
2. explanatory: designed to test a hypothesis, study design should be appropriate to test that hypothesis |
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what are the four types of observational studies?
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1. ecological
2. cross sectional 3. case control 4. cohort |
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what are the key features in ecological studies
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1. conducted at the population level...not individual
2. difference in outcome between populations are related to population characteristics that are risk or protective factors |
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what are the key features in cross sectional studies
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1. aka...prevalence studies
2. select a sample of subjects and determine the distribution of exposure in sample 3. exposure and disease outcome are determine simultaneously 4. can not be used to determine temporal relationship between exposure and disease |
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what are the key features in case control studies
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1. retrospective study
2. case and control group 3. if exposure is a risk factor, the proportion of cases should be greater than the controsl exposed 4. recall bias can be a problem since past events are involved |
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what are the key features in cohort studies
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1. prospective study
2. diseased free at start 3. divide participants according to exposure and follow over time to look for development of disease...EXPENSIVE 4. use to calculate relative risk 5. attrition and selection bias are other issues to consider |
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what are the difference between clinical trials and community trial...experimental studies
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1. clinical: experimental study where researcher controls exposure (OHTS, AREDS, ATS and EDTRS)
2. community: used to evaluate the benefits of new policies and programs (vaccine trials) |
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how must you evaluate the results of a study
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1. is it relevant to YOUR clinical practice?
2. is it statistically significant...must be more than 5% (p=0.05)...since 1/20 risk that results are due to chance |
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what are the three types of bias
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1. selection
2. information 3. confounding |
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what is selection bias
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subjects in the study have characteristics that preferentially lead to a particular outcome (avoid by random choosing)
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what is information bias
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1. arises from systematic errors in measuring either the independent variable or the dependent variable
2. systematic errors in measurement or limited precision in measurement |
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what is confounding bias
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1. an extraneous correlation of disease that, because of its association with the risk factor of interest, accounts for some or all of the observed association
2. eliminate or reduce with careful study design and participant selection |
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what is clinical epidemiology
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1. studying groups of people to gather evidence to help make clinical decisions in patient care
2. studying variations in the outcome of illness and the reasons for the variation |
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what is evidence based medicine
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integration of current best evidence with clinical expertise, pathophysiological knowledge, and patient preferences to make health care decisions
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what is conditional probability
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prevalence information can be used to estimate the pre-test odds of a patient having a particular condition or disease
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what is the significant findings in the ocular hypertension treatment study
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treating ocular hypertension can delay or prevent the onset of POAG
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what is the significant findings in the age related eye disease study
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high levels of antioxidants and zinc can reduce the risk of developing ARMD
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what is the significant findings in the amblyopia treatment study
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found the atropine therapy works well as traditional patching therapy for the treatment of amblyopia
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what is the significant findings in the early treatment of diabetic retinopathy
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1. aspirin has no effect on progression of retinopathy
2. focal treatment for macular edema reduced the risk of vision loss 3. small reduction in severe vision loss using scatter treatment in NIDDM |
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what was the purpose of the orinda study
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1. cheapest
2. least technical 3. most effective screening for find essentially all elementary school childrens vision problems |
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what were the results of the orinda study
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1. MCT was the cheapest, most efficient
2. nurse observation was not very good because it they didnt refer anybody 3. mass vision test was not good because they refered everyone...and it was really expensive 4. they did not find a screening that a teacher of faculty can do accurately though |
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what was the purpose of the framingham study
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to determine the epidemiology of ocular pathology in the study group
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who were the participants in the framingham study
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1. prospective study
2. survivors of the framingham heart study 3. 2477 participants (52-85) |
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what were the results of the framingham study
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1. legal blindness: 8.9/1000
2. visual impairment: 33/1000 3. established the C/D ratio we go by as a standard: 0.28 visual impairment increases with age |
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what was the purpose of the baltimore study
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to determine the blindness and visual impairment rates among an urban, multiracial population
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what was the difference between framingham and baltimore study
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1. framingham: up middle class caucasian suburb
2. baltimore: lower income multiracial |
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who was involved in the baltimore study
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1. 5300 participants
2. age 40 and older 3. equal number of black and white participants 4. prospective study |
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what were the results of the baltimore study? prevalence?
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1. blindness and visual impairment increased with age in both groups
legal blindness: white: 9.3/1000 black: 15/1000 POAG white: 1.7% over 40 black: 5.6% over 40 |
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what was the prevalence of legal blindness and visual impairment in the framingham study
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legal blindness: 8.9/1000
visual impairment: 33/1000 |
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when do you use MEAN and MEDIAN
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MEAN: when there is a LOW variability in the numbers
MEDIAN: when there is a HIGH variability in the numbers |
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what are the properties of a normal curve
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1. total area under the curve equals 1
2. extends indefinitely in both directions, approaching the horizontal 3. symmetric about the mean 68%: _+ 1 95%: _+ 2 99%: _+ 3 |
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what are the stages of appropriate levels of prevention
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1. susceptibility: primary
2. presymptomatic: secondary 3. clinic disease & disability: tertiary |
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what is an example of each type of prevention?
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primary: safety glasses
secondary: early detection tertiary: treatment/rehabilitation |
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what is happening at each stage of the disease
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1. susceptibility: no disease, risk factors present
2. presymptomatic: no manifest disease, but pathogenic stages started to occur 3. clinic disease: recognizable signs and symptoms 4. disability: onset |
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stage ONE of demographic transition
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UNDEVELOPED
1. increase birth rate 2. increase death rate 3. slow population growth |
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stage TWO of demographic transition
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DEVELOPING/TRANSITION
1. increase birth rate 2. decrease death rate 3. high population growth |
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stage THREE of demographic transition
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DEVELOPED
1. decreased birth rate 2. decreased death rate 3. slow population growth |
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definition of incidence...word and number
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1. the number of new cases of a disease in a population over a period of time
2. # of new cases/population at risk |
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definition of prevalence...word and number
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1. # of individuals who have a particular disease at a given time
2. # of existing cases/population at risk |
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what is the difference between descriptive and analytical studies
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1. descriptive: determine the amount and distribution of a disease within a population by person, place and time
2. analytical: focused study on the determinants of a disease or reasons for high or low freq in specific group |
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what is analytic studies
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1. once descriptive studies have identified groups with high or low rates of disease, analytic studies are performed to determine WHY the rate is high or low
2. used to determine disease rates 3. determine risk factors |
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retrospective vs. prospective
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1. retro: look for past exposure to factor in cases and controls
2. pro: follow to see freq of disease development |
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what type of study provide us with INCIDENCE RATES
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PROSPECTIVE
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what is relative risk ratio
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ratio of incidence rates of those exposed to those not exposed
RR>1, risk factor RR=1, no risk RR<1, protective |
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what is screening
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presumptive identification of unrecognized disease or defect by the application of tests, exam, or other procedures that can be applied RAPIDLY to sort out apparently well persons who probably have a disease form those who probably does not
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how is screening different than diagnostic testing...characteristic of IDEAL SCREENING
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screening is QUICK. INEXPENSIVE, NON INVASIVE
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what determines validity in screenings
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1. sensitivity
2. specificity |
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sensitivity...word and number
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1. the ability of a test to identify correctly those who have the disease
2. true positive/all with disease |
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specificity...word and number
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1. the ability of a test to identify correctly those who do not have the disease
2. true negative/all without disease |
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what is predictive value
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the ability of a screening test to predict the presence or absence of a disease depends on...
1. prevalance 2. sensitivity/specificity |
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does specificity affect yield
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FUCK NO!!
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