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Epidemiology > Epi Final > Flashcards

Epi Final Flashcards

1
Q

Purpose of Analytical Studies?

(2)

A
  • ID & explain the cause of dz
  • numerically assess risk factors
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2
Q

3 parts of an Analytical Study?

A
  1. Data collection
  2. Data analysis
  3. Data interpretation
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3
Q

Study type that compares dz occurrence between “exposed” & “non-exposed”

A

Cohort study

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4
Q

2 Strengths of Cohort Studies

A
  • Rare exposure
  • can examine multiple outcomes of a single exposure
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5
Q

Weaknesses of Cohort Study

(2)

A
  • Not good for rare dz.
  • time consuming if there is a long period between exposure & dz.
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6
Q

Prospective Cohort follows groups from _______ to ________.

A

present to future

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7
Q

Strengths of Prospective Cohorts

(3)

A
  • measure Incidence
  • describes temporal relationships
  • collect data on possible confounders
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8
Q

Weaknesses of Prospective Cohorts?

(3)

A
  • Expensive & long
  • Lack of follow-up can affect validity
  • Requires a large # of subjects
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9
Q

Retrospective Cohort follows subjects from _______ to _______.

A

present to past

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10
Q

Strengths of Retrospective Cohorts

(3)

A
  • data is already present
  • cheap
  • easy to perform
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11
Q

Weaknesses of Retrospective Cohorts

(2)

A
  • Need good records → confounders
  • Selection bias
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12
Q

Relative Risk looks at what?

A

how many times more/less likely exposed individuals are to get the dz. relative to non-exposed individuals

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13
Q

How do you calculate RR?

A
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14
Q

Purpose of Cofidence Interval (CI)?

A

allows you to determine whether or not the RR/OR can be deemed statistically significant

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15
Q

When is the result said to be statistically significant?

(in regards to the CI)

A
  • if the CI falls entirely on either side of the null value (1.0)
  • has be 95% or higher
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16
Q

_______ are study subjects who have the disease of interest in Case-Control Studies.

A

Cases

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17
Q

What is the purpose of Case-Control Studies?

A

compare frequency of exposure factors in cases w/ dz and cases w/o dz.

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18
Q

_______ are subjects who are dz free at the time of selection in Case-Control Studies.

A

Controls

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19
Q

Where does Case Selection come from?

A
  • all cases in a defined population or from the general population
  • often more convient
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20
Q

Controls selected from CCS should be __________ to cases in every respect except _______.

A
  • identical
  • disease
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21
Q

How do you calculate Odds Ratio (OR)?

A
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22
Q

Which study uses OR?

A

Case-Control Studies

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23
Q

4 Strengths of Case-Control Study?

A
  • Rare dz.
  • Multiple exposure
  • cheap & fast
  • Small # of subjects
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24
Q

4 Weaknesses of Case-Control Studies?

A
  • No Incidence or Prevalence
  • Bias→ recall, selection, information, misclassification
  • Difficult to establish temporal relationships
  • Cofounding
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25
Q

Objective of Randomized Clinical Trials (RCTs)?

A

subjects followed over time to test possible effects of therapeutic & preventative interventions

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26
Q

Which RCT evaluates whether agent/procedure reduces risk of dz. developing in those currently free from dz?

A

Field Trial

(Prevention Trial)

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27
Q

3 Strengths of RCTs?

A
  • Control over study situation
  • Casual relatioship can be established
  • Reduced confounding & bias
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28
Q

5 Weaknesses of RCTs?

A
  • May not accurately represent normal population
  • Need large sample size → $$
  • May be timely
  • Ethical issues
  • Bias if no blinding is present
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29
Q

Test that is:

  • Applied to animals showing CS of dz.
  • Confirms or classifies dz. status
A

DX tests

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30
Q

This test is used to:

  • to ID undiagnosed cases of dz in apparently healthy populations
A

Screening tests

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31
Q

Sensitivity means?

A

Probability that a disesed patient will test positive

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32
Q

Specificity means?

A

Probability that a healthy patient will test negative

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33
Q

What must you use to calculate Sensitivity & Specificity?

A

Gold Standard Tests

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34
Q

True Positive (TP) means?

A

a diseased patients that test positive for dz.

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35
Q

True negative (TN) means?

A

healthy patient that tests negative for dz

36
Q

False Positive (FP)?

A

Healthy patient tests POSITIVE

37
Q

False Negative (FN)?

A

Sick patient tests NEGATIVE

38
Q

Calculate Sensitivity!

A

TP

Dz (+)

39
Q

Calculate Specificity!

A

TN

Dz. (-)

40
Q

Calculate Prevalence!

A

_ Dz (+) _

Total tested

OR

_ (a+c) _

(a+b+c+d)

41
Q

Calculate Positive Predictive Value (PPV)!

# of diseased subjects that test (+) for dz of interest

A
42
Q

Calculate Negative Predictive Value (NPV)!

Healthy subjects that test (-) for dz of interest

A
43
Q

When is it feasible to implement a Screening Program?

(5)

A
  • Dz. is important to public health
  • Test will have a high level of case detection & low level of FPs
  • Have facilities available for follow-up & TX
  • Test doesn’t harm patient
  • cost effective
44
Q

List the 6 steps of Natural HX of Dz in order!

A
  • biological onset
  • preclinical phase
  • detectable preclinical phase
  • lead time
  • critical points
  • clincal phase
45
Q

Phase of Natural HX of DZ where there are no symptoms & may only have sub-cellular changes in DNA?

A

Biological onset

46
Q

Phase of Natural HX from biological onset to developement of CS of dz?

A

Preclinical Phase

47
Q

The point during preclinical phase before symptoms develop, but dz can be detected using screening tests?

A

Detectable preclincal phase

48
Q

Interval by which time of DX is advanced by early screening & early detection methods?

A

Lead Time

49
Q

Point(s) in natural HX BEFORE which TX in effective?

A

Critical Points

50
Q

List order of the Chain of Infection!

A

agent → reservoir/host → portal of exit → transmission → portal of entry → susceptible host

51
Q

T/F: All Amplifier Host = Essesential Hosts

A

FALSE

52
Q

T/F: All Essential Hosts= Amplifier Hosts

A

TRUE!!!

53
Q

Key Requirement for INFECTION!

A

host shows IMMUNE RESPONSE

54
Q

Time period btwn exposure to an agent & onset of CS of dz?

A

Incubation period

55
Q

The interval between exposure to an infectious organism and the clinical appearance of disease

A

Latent Period

56
Q

Clinically apparent infection = ?

A

DISEASE

57
Q

4 possible outcomes of Infection?

A
  • Immunity
  • DZ
  • Subclincal Infection
  • Carrier state
58
Q

Antigenic Drift is responsible for what 2 things?

A
  • small, gradual mutations
  • account for annual epidemics
59
Q

Antigenic Shift is responsible for what things?

A
  • abrupt, major changes
  • new disease states (ex. H1N1)
60
Q

Calculate Infectivity!

A

_ infected animals _

exposed animals

61
Q

Calculate Attack Rate!

(infectivity during an outbreak)

A

# new cases per period

entire population

62
Q

Calculate Secondary Attack Rate!

(susceptible animals following known contact w/ 1° case)

A

_ # of new cases from 1° case _

all those healthy after contact w/ 1° case

63
Q

Calculate Pathogenicity!

(proportion of infected animals that develop CS)

A

_ # of infected w/ C.S. _

All infected individuals

64
Q

Calculate Virulence!

(# of animals that develop severe dz)

A

_ # w/ severe dz _

All dz. animals

65
Q

Calculate Case-Fatality Rate!

(proportion of cases that evenutally die from dz)

A

_ # fatal cases _

All dz animals

66
Q

Calculate Mortality Rate!

(reflects burden of deaths from dz in the population as a whole)

A

_ # of deaths from dz _

Total population

67
Q

What season are respiratory diseases more prevalent?

A

Winter

68
Q

What season are food-borne & vector-borne diseases more prevalent?

A

Summer

69
Q

CDC definition of Herd Immunity?

A

accomplished when # of animals w/ acquired immunity is so great that, under natural conditions, a infectious agent can’t enter into or spread w/in a herd.

70
Q

What happens to Herd Immunity when you introduce susceptible animals to a herd?

(2)

A
  • host resistance is reduced
  • Increase in occurrence of infection & dz.
71
Q

What happens during the Descriptive Phase of an Outbreak Investigation?

A
  1. describe dz parameters
  2. take herd HX
  3. form case definition
  4. make epidemic curve
72
Q

List the 3 components of Case Criteria.

A
  1. CS
  2. immunologic response
  3. ability to detect agent & confirm it as the cause
73
Q

List the 4 Phases of Outbreak Investigation.

A
  1. Descriptive
  2. Analytical
  3. Invervention
  4. Control
74
Q

Which 2 biological disasters are FAR more likely to occur?

A

Natural disasters

Accidental disasters

75
Q

List the 3 consequences of all Biological Disasters

A

Health/Economic impact

Psychological impact

Improved Preparedness

76
Q

Agroterrism definition?

A

intent to indirectly attack persons by destruction of plant & animal infastructure of a nation

77
Q

CDC Bioterrorism definition?

A

deliberate release of viruses, bacT or other agents used to cause illness/death in people, animals or plants

78
Q

4 Clues to Occurence of Agro/Bioterrorism

A
  • Clustering of dz (normally healthy populations
  • Dz outside normal/expected season
  • Dissemination over very large areas quickly → if airborne
  • Acute morbidity/mortality
79
Q

These agents belong to what CDC Category?

Ebola

  • Y. pestis* (plague)
  • B. anthracis* (anthrax)
  • C. botulinum* (botulism)
  • V. major (*small pox)
  • F. tularensis* (tularemia)
  • Lassa* virus
A

Category A

highest priority

80
Q

What 3 requirements must an agent meet to be considered CDC Category A agent?

A
  • easily transmitted from person to person
  • High mortality rate
  • requires special action for public health preparedness
81
Q

What 3 requirements must an agent have to be considered a CDC Category B agent?

A
  • moderately easy to disseminate
  • Moderate morbidity & low mortality rates
  • requires enchanced DX capacity & DZ surveillance
82
Q

These agents are all classified under what CDC Category?

  • Brucella*
  • C. burnetti* (Q fever)
  • Salmonella, E. coli, Shigella*
  • B. mallei (*Glander’s)
  • B. pseudomallei (*Melioidosis)
  • C. psittaci* (Psittacosis)
  • R. prowazekii* (epidemic typhus fever)
  • Alphaviridea* (EEE, WEE, VEE)
  • Crytosporidium*
  • V. cholerae*
A

Category B Agents

second highest priority

83
Q

What 3 requirements are needed to be considered a CDC Category C agent?

A
  • emerging pathogens→ ability to be engineered for mass dissemination
  • easy to produce & spread
  • potential for high morbidity/mortality rates → major health probs.
84
Q

List the 2 CDC Category C agents!

A

Nipah virus

Hanta virus

85
Q

List the 5 agents in Tier 1 of the Select Agent Program!

HHS & APHIS of USDA

A
  1. FMD→ highest priority
  2. Classical Swine Fever
  3. Newcastle Dz.
  4. Vesicular stomatitis
  5. Avian influenza → highly pathogenic form
86
Q

What is the lead federal agency in safeguarding America’s livestock & poultry health?

A

APHIS of the USDA

Epidemiology (6 decks)

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