Final

Question 1

What are the five key questions that should be asked for evaluating epidemiologic associations? Explain them.

1-2

Answer 1

Could the association have been observed by chance?

use statistical tests, apply biostatistics

Could the association be due to bias?

systematic errors? evaluate group selection how information was collected and then analyzed. search for errors errywhere.

does the Aso represent a C&E effect?
utilize Hill’s criteria of causality: including criteria such as: consistency, speciificty, analogy, temporality, and coherence.

Question 2

Please describe what is meant by sampling distribution, areas under the normal curve and levels of significance? (LECTURES)

Answer 2

of given population, it is the probability distribution of frequencies of a range of different outcomes that could possibly occur for a statistic of a population.

A confidence interval is an interval estimate combined with a probability statement. used to express the degree of uncertainty associated with a sample statistic

Question 3

Define Reliability.

Answer 3

Repeated measurement RR- degree of consistency btwn measurements of the same indivdual or various occasions. - measuring height at various times

internal consistency RR - evaluate the degree of agreemen/homogenity w/in a questionnaire measure of a personal charac’ or psychological attitude. Like observing self-report questionnaires on anxiety towards cancer and ensuring it is asking the same thign

interjudge - reliability assessments based on agreement among trained experts conducting the same test. esdpecially in psychology. various psych’s evaluating mental condition of a psych patient.

Question 4

Define screening. What is the purpose of screening?

Answer 4

PURPOSE - for secondary prevention of morbidty/mortality in public health field.
DEFINE application of a test to detect a disease or condition for one who may not have any symptoms of it.

Question 5

Describe in detail Sensitivity and Specificity with in relationship to the table. Please provide the definition, formula for each and examples. (LECTURE AND TEXT 476-479)

Answer 5

sensitivity - ability of the test to ID correctly all screened individuals who have disease. taking a test that tested for 10 ppl out of 100 had diabetes but it resulted in 40 ppl. (low sensitivity.)
#' True positives/ sum' true positives & false negatives

specificity - abiliy of the test to ID only nondiseased ppl who don't have it. if not specific - ppl that don't have it will have to get tested again.
#' true negatives/ sum' false positives & true negatives

Question 6

1) Define what is meant by infectious disease in epidemiology.
2) Explain in detail the Epidemiologic triangle and

Answer 6

1)investigating the occurrence of epidemics of infectious/communicable diseases.
2) explaining etiology of infectious disease, explain the occurence of disease outbreaks,
3 factors in pathogenesis of disease

Question 7

Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

Means of Transmission of infectious diseases: Direct and Indirect

Answer 7

direct - between an infected person and a susceptible person. sexual contact, contact with oral secretions

indirect spread when an infected person sneezes or coughs, sending infectious droplets into the air. If inhaled or land directly in their eyes, nose or mouth, they risk becoming ill.

Question 8

Explain in detail the following characteristics of infectious disease agents with examples (TEXT):

Pathogenicity

Answer 8

capacity/ability of the agent to cause disease in the infected host. such as a cold having low pathogenecity but when a person has a weakened immune system the pathogenecity increases

Question 9

Explain in detail the following characteristics of infectious disease agents with examples (TEXT):

Virulence

Answer 9

agent’s capacity to induce disease. # of deaths / total # of infected cases. if disease is fatal, it is measured by case fatality rate)CFR) rabies is extremely virulent and has a high CFR

Question 10

Explain in detail the following characteristics of infectious disease agents with examples (TEXT):

Toxigenicity

Answer 10

capacity of the agent to produce a toxin or poison. pathologic effect of agents for disease such as botulism is a result from the toxins not the microorganism itself.

Question 11

Explain in detail the following characteristics of infectious disease agents with examples (TEXT)

Resistance

Answer 11

ability of the agent to survive adverse environmental conditions. hepatatitis is very resistant by the influenza virius is not.

can also be applied to the host.

Question 12

Explain in detail the following characteristics of infectious disease agents with examples (TEXT):

Antigenicity

Answer 12

ability of the agent to induce antibody production in the host. immunogenicity. agents may or maynot induce long-term immuniuty against infectin. repeated reinfection common with gonococci but not measles virus.

Question 13

Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

portals of exit and entry

Answer 13

portals of exit are where agents may leave the body and must be approp’s for the specific agent. to produce infection, the agent must exit source in sufficient quantity to survive environment and to overcome the defenses surrounding the portals of entry in new host.

Question 14

Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

Incubation period

Answer 14

time interval between exposure to infectious agent and appearance of first signs/sympotoms of disease. once it replicates w/in host the INC period is typidcally fixed.

used when attempting to fix the source of an outbreak depending on the lenght of time, such as to determine cause of outbreak of foodborne illness to ID possible etiologic agents since each has a characteristic INC periods.

Question 15

Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

Host defense mechanism.

Answer 15

high pH of gastric juices, mucous membranes, presence of skin. their ability fnd off agents may decrease with age.

active - long lasting but takes time to develop

passive - preformed antibody administered which makes immunity lasts for a short duration.

Question 16

Explain in detail the following characteristics of infectious disease agents with examples (TEXT):

Infectivity

Answer 16

capacity of the agent to enter/multiply in a susceptible host and then produce infection or disease. measles has high infectivity

Question 17

What are the five key questions that should be asked for evaluating epidemiologic associations? Explain them.

4-5

Answer 17

cound other confounding variables have accounted for the obesrved relationship?

consider any other third variables that were not considered during the original analysis of design. be sure there is no masking of an association between an exposure and an outcome.

to whom does this associaion apply?

is the association representative of the relevant population considering the participation rate of the study? what does it mean for the group?

Question 18

2 types of validity

Answer 18

content VV- how well a test measures the cahracteristic it is measuring, like how well exams evaluate comprehension

construct VV - degree to which a test measures what it means. language proficiency, to what extent?

Question 19

(part 2) Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

Host defense mechanism.

Answer 19

artificial active - vaccion induced infection that stimulates antibody production in host. response mimics the natural infection but presents little to no risk to host.

natural, active - results from infection by the agent. ex:acquiring long-term immunity to measles because of a naturally acquired infection

Question 20

What are the appropriate situations for screening tests and programs? (LECTURE AND TEXT-468)

Answer 20

APPROPRO’

• social - important to individual and community, favorable cost-benefit rato, high public acceptance
• scientific - ID should occur during prepathogenesis with enough lead time. enough information is known on prevention methods, prevalence is high.
• ethical - provider-initiated service, can alter natural history of condition, suitable, acceptable screening tests.

Question 21

Five portals of exit and entry of infectious agents

Answer 21

1 - respiratory secretions - entry - resp tract. (measles)
2 - feces - entry - alimentary(digestive) tract (typhoid)
3 - lesions - entry - skin, genital membranes (gonorrhea)
4 - conjunctival exudate - entry - ocular mcous membrane (trachoma)
5 - blood - entry - broken skin (malaria, yellow fever)

Question 22

the time specific forms of validity

Answer 22

criterion-referenced predicitve VV - ability of a measure to preduct some at attribute in the future - how likely one is going to have diabetes based on health habits and attitudes

criterion referenced concurrent - extent to which the results of a particular test, or measurement, correspond to those of a previously established measurement for the same construct

Question 23

(part 3) Define, describe in detail and provide an application of its use for the following: (TEXT AND LECTURE)

Host defense mechanism.

Answer 23

natural, passive - preformed antibodies during pregnancy transferrred across placenta to fetal bloodstream to produce short-term immunity to newborn

artificial passive - preformed antibodies against specific disease are admiistered to exposed individual to confer protection against disease. prophylaxis against hepatitis by admin of immuneglobulin to exposed peoples.