Final Exam Flashcards
(135 cards)
1
Q
What is an infectious disease
A
A disease caused by a microorganism and pan potentially transfer to humans (e.g. food poisoning)
2
Q
What is a communicable disease
A
An infectious disease that is contagious and transferrable from person to person (e.g. flu)
3
Q
What is the epidemiological triangle
A
A model used to explain the etiology of infectious diseases
4
Q
What are the 4 main factors in the pathogenesis of disease
A
Host, agent, environment, and time
5
Q
What is the agent of infectious disease
A
Microorganisms capable of producing the disease (necessary but not sufficient cause of disease)
6
Q
What is infectivity
A
Capacity of an agent to enter and multiply in a susceptible host and thus produce infection/disease
7
Q
What is subclinical disease for infection response in the host
A
Infection without clinical illness and exposure without infection
8
Q
What is clinical disease for infection response in the host
A
Moderate severity/illness, clinical and severe disease, and death
9
Q
What is below visual change for cell response to infection
A
Exposure without cell entry and incomplete viral maturation
10
Q
What is a discernible effect for cell response to infection
A
Cell transformation or dysfunction and lysis of cell
11
Q
What is pathogenicity
A
Capacity of an agent to cause active clinical disease in the infected host
12
Q
What is clinical disease
A
Obvious observable or detectable symptoms (mild, moderate, severe, and death)
13
Q
What is virulence
A
A degree of pathogenicity that indicates the severity of disease after infection occurs
14
Q
What is a susceptible host
A
The target of a specific infectious agent
15
Q
What are 12 portals of exit out of a host
A
Eyes, ears, nose, mouth, broken skin, mammary glands, placenta, vaginal secretions, urethra, anus, seminal vesicle, skin flakes
16
Q
What are 12 portals of entry into a host
A
Eyes, ears, nose, mouth, broken skin, placenta, vagina, urethra, anus, capillary, digestive tract, respiratory tract
17
Q
What is vertical transmission
A
From mother to child
18
Q
What is horizontal transmission
A
From infected individual to another susceptible individual
19
Q
What are 3 modes of vertical transmission
A
Mammary glands (milk), placenta (blood), vagina (secretion, blood)
20
Q
What are 2 modes of horizontal transmission
A
Direct (person to person) and indirect (via intermediary source)
21
Q
What are 2 methods of direct transmission
A
Direct contact (skin to skin, exchange of bodily fluids) and droplets (sneezing, coughing, or talking)
22
Q
What are 3 types of indirect transmission
A
Airborne, vector borne (animate objects), and vehicle born (inanimate objects)
23
Q
How does airborne transmission work
A
Infectious agents are carried by dust or droplet nuclei suspended in air
24
Q
What is a vector
A
A living insect or animal involved with transmission of a disease agent
25
What are 4 kinds of vehicles that can transmit disease agents
Water, food, soil, and fomites
26
What are fomites
Objects or materials likely to carry infection (doorknob, clothing, unsterilized medical equipment, etc.)
27
Can diseases have multiple modes of transmission
Yes
28
What is a host
A person or animal susceptible to disease
29
What does the degree of severity of an infection depend on
The host's ability to fight off the infectious agent
30
What are the two types of defenses mechanisms in a host
Innate response (hours) and adaptive response (days)
31
What is acquired immunity
Immunity that develops during your lifetime
32
What are the two kinds of acquired immunity
Active and passive
33
What are the two kinds of active and passive immunity
Natural and artificial
34
What is active immunity
Develops in response to an infection or vaccination
35
What is passive immunity
Develops after you receive antibodies from someone or somewhere else
36
What is natural active immunity
Antibodies developed in response to infection, provides long lasting immunity
37
What is artificial active immunity
Antibodies developed in response to a vaccination, long lasting immunity
38
What is natural passive immunity
Antibodies received from mother (e.g. through breast milk), immediate and temporary protection
39
What is artificial passive immunity
Antibodies received from medicine (e.g. gamma globulin injection or infusion), immediate, temporary protection
40
Which provides a larger, faster, and stronger response (1st or 2nd exposure)
2nd exposure
41
What is the environment
The domain in which disease-causing agents may exist, survive, or originate
42
What are the two kinds of environment
Physical (weather, temp. humidity, etc.) and social (behavioral and cultural characteristics of a group of people)
43
What's a reservoir
The habitat in which infections agents live, grow, and multiply
44
What are the 3 kinds of reservoirs
Environmental (e.g. plants, soil, contaminated food/water), animal or insect, and human
45
What are the 2 kinds of human reservoirs
Acute clinical cases and carriers
46
What are acute clinical cases
People infected with the disease agent who become ill
47
What are carriers
People who harbor infectious agents but aren't ill
48
What are the 4 types of carriers
Healthy, incubatory, convalescent, and chronic
49
What is a healthy carrier
People with infections that will never develop the illness but can transmit it (common with polio)
50
What are incubatory carriers
People who will become ill but start transmitting infection before symptoms present (common with HIV or measles)
51
What are convalescent carriers
People who continue to be infectious after recovery from illness (e.g. salmonella)
52
What are chronic carriers
People who keep harboring infection for a year or longer after recovery (e.g. Hep B)
53
What are super-spreaders
Someone who is responsible for infecting many people
54
What is the 80/20 rule
In any given outbreak, 20% of individuals are thought to contribute at least 80% to transmission of pathogen
55
What type of carrier was Typhoid Mary
Asymptomatic/healthy and chronic
56
What is an incubation period
The time between exposure to infectious agent and appearance of first signs and symptoms of disease which can help determine what the exposure may have been
57
What is a sign of disease
Something which can be visibly observed (temperature, color, etc.)
58
What is a symptom of disease
Something felt by the diseased (dizziness, nausea, exhaustion, etc.)
59
What is generation time
Time between exposure to an infectious agent and the maximal infectivity of the host (cab be before active symptoms) which is good to determine spread of infectious agents when lots of subclinical cases
60
What is an epidemic (epidemic) curve
A graph plotting the distribution of cases by time of onset
61
What is a common source epidemic curve
We know exactly where the source is coming from
62
What are the 3 kinds of common source epidemic curves
Point source, continuous, and intermittent
63
What is a point source epidemic curve
Exposed to same common source (single meal or event), and majority of cases occur within one incubation period (e.g. food poisoning)
64
What is a continuous common source epidemic curve
Lasts more than one incubation period (e.g. water pump)
65
What is an intermittent source epidemic curve
Multiple peaks with no relation to incubation period (e.g. contaminated food sold over period of time)
66
What is a propagated source epidemic curve (3 characteristics)
No common source, caused by spread of infectious agent from one person to another or via intermediate host, multiple peaks separated by one incubation period
67
What are the 2 kinds of epidemic curves
Common source and propagated
68
What is attack rate
The proportion of a group that experiences the outcome under a study over a given period
69
When is attack rate used
Only for acute infectious disease outbreaks or acute exposures of large groups to toxic agents
70
What is a case
A person in a population identified as having disease
71
What are new cases
Initial cases and secondary cases
72
What are initial cases
Index cases and coprimaries
73
What are index cases
The case that first comes to attention of public health authorities
74
What are coprimaries
Cases related so closely in time that they're considered to belong to same generation of cases
75
What are secondary cases
People who become ill after a disease has been introduced into a pop. from contact with a primary case
76
What is secondary attack rate
A measure of infectivity which indexes the spread of disease in a family, household, dwelling unit, dormitory, etc.
77
What is case fatality rate
Proportion of deaths caused by disease among those who have the disease during a time interval
78
What does case fatality rate index
The virulence of a particular disease within a specific population
79
What is basic reproductive rate
Measures transmissibility (contagiousness) by seeing number of infections produces on average by an infected individual when virtually all contacts are susceptible
80
What are 8 control measures to stop disease spread
Hand washing, PPE, clean water, sanitation, food safety (clean, separate, cook, and chill), mosquito control, blood screening, vaccines
81
What is herd immunity
Immunity of a population, group, or community against an infectious disease when a large proportion of people are immune through vaccinations or prior infections
82
What does critical vaccine threshold indicate
The higher R(0) a disease has, the greater need their is for vaccine coverage
83
What are the 10 steps of investigation infectious disease outbreaks
1: Establish existence of an outbreak
2: Verify diagnosis
3: Construct a working case definition
4: Find cases systematically and record info.
5: Perform descriptive epidemiology
6: Develop a hypothesis
7: Evaluate hypothesis epidemiologically,
8: Reconsider, refine, and re-evaluate hypothesis
9: Implement control and prevention measures
10: Communicate findings
84
What is a case definition
A standard set of criteria to decide whether an individual should be classified as having the health condition of interest
85
What should a case definition have
Clinical criteria, setting of outbreak investigation (person, place, and time), but not exposure or risk factor being evaluated
86
What is passive surveillance
Sending letter or describing the situation and asking for reports of similar cases
87
What is active surveillance
Telephoning or visiting facilities to collect info. on any additional cases
88
What should data collection include (5 things)
Identifying info., demographic info, clinical info, risk factor info, and reporter info.
89
What is screening for a disease
Presumptive identification of unrecognized disease or defects through testing, examinations, or other rapid procedures which are followed by diagnostic tests to confirm actual disease
90
What are the 4 characteristics of screening tests
Detect potential disease indicators, target large numbers of asymptomatic individuals, simple and cheap, and results indicate suspicious of disease
91
What are the 4 characteristics of diagnostic tests
Establish presence or absence of disease, target single asymptomatic individuals or asymptomatic individuals with positive screening test, maybe invasive and costly, provide definite diagnosis
92
What are the 2 kinds of screening tests
Mass (population) screening and selective (targeted screening)
93
What is the difference in the 2 kinds of screening tests
Mass screens entire population regardless of risk status (e.g. temp at airport) while selective screens specific groups at high risk for disease (e.g. HIV screening for sex workers)
94
What are the 4 social considerations for screening tests
Health problem should be important to individual and community, diagnostic follow-up and intervention should be available for all who need them, favorable cost-benefit ratio, and high public acceptance
95
What are the 3 scientific considerations for screening tests
Natural history of condition adequately understood (identifies early stages of disease and biological markers of progression), efficacy of prevention and occurrence of side effects is known, and prevalence of the disease or condition is high
96
What are the 2 ethical considerations for screening tests
Program can alter natural history of condition in significant proportion of those screened and suitable, acceptable tests for screening and diagnosis as well as acceptable, effective prevention methods
97
What are the 5 characteristics of a good screening test
Simple, rapid, inexpensive, safe, and acceptable
98
What are the 2 evaluations of screening tests
Reliability (precision) and validity (accuracy)
99
What is reliability
Ability of a measuring instrument to give consistent results on repeated trails
100
What is validity
Ability of measuring instrument to give a true measure
101
What are the interrelationships between reliability and validity
A measure can be highly reliable but invalid (e.g. broken scale) but a measure cannot be valid but unreliable
102
What is the gold standard
The diagnostic test or benchmark that's best available under reasonable conditions (not perfect but best available)
103
What are the 6 measures of validity
Sensitivity, specificity, predictive positive value, predictive negative value, accuracy, and prevalence
104
Which measures of validity show characteristics of a test
Sensitivity and specificity
105
What measures of validity show clinical relevance of a test
Positive and negative predictive values show how well a measure is clinically testing what we want it to test
106
What is special about accuracy and prevalence
Can only be used when the same individuals are examined in screening and gold standard
107
What is sensitivity
The proportion of people tested positive among people who had the disease
108
What is specificity
The proportion of people who tested negative among people who were disease free
109
What is positive predictive value
The proportion of people who actually had the disease among people who tested positive
110
What is negative predictive value
The proportion of people who are actually disease free among people who tested negative
111
What is accuracy
The degree of agreement between the test result and the gold standard
112
What happens to predictive values when there is a lower prevalence in a population
Positive predictive value will go down while negative predictive value will go up
113
How should the cut point be moved to improve sensitivity
Towards the normal (also increases false positives)
114
How should the cut point be moved to improve specificity
Towards the range typically associated with disease (Increases false negatives)
115
What are 4 procedures to improve sensitivity and specificity
Retrain screeners to reduce misclassification, recalibrate screening instruments to reduce imprecision, use a different test, or use more than one test
116
What are the 3 sources of bias in screening
Lead time bias, length bias, and selection bias
117
What is lead time bias
The perception that a screen-detected case will live longer because the disease was identified early
118
What is length bias
Disease identified through screening has lower, less aggressive course and therefore better prognosis (so screening doesn't actually help that much and may actually do more harm)
119
What is selection bias
Motivated participants have a different probability of disease than do those who refuse to participate
120
What are 7 health effects attributed to environmental exposures
Cancer, lung disease, infertility, reproductive impacts, infectious diseases, neurologic diseases, and dermatologic problems
121
What is environmental epidemiology
Study of disease conditions (occurring in population) that are linked to environmental factors
122
What are environmental exposures
Exposures outside the control of the exposed individual
123
What are the 2 kinds of study designs
Descriptive (cross-sectional) and analytic (ecologic, cohort, and case-control)
124
What are the 3 characteristics of descriptive study designs
Helpful to set priorities, identify hazards, and make hypotheses for new occupational risks
125
What are the 2 characteristics of analytic study designs
Used to show exposure-effect relationships and effects of low-level exposures
126
What are the 2 end points for occupational exposures
Morbidity (self-reports and symptoms and results of clinical examinations) and mortality (compares mortality rates of exposed to nonexposed workers in same industry)
127
What is the healthy worker effect
Employed populations tend to have lower mortality experience than general population (may reduce measure of effect for an exposure that increases morbidity or mortality)
128
What is sick building syndrome
Symptoms diminish when affected person leaves the building
129
What are the 5 tiers of hazard surveillance from most effective to least effective
Elimination (physically remove the hazard), substitution (replace the hazard), engineering controls (isolate people from hazard), administrative controls (change way people work), and PPE (protect worker with equipment)
130
What is the sentinel health effect
Case of unnecessary disease, unnecessary disability, or untimely death whose occurrence is a warning signal that the quality of preventative or medical care may need to be improved (secondary prevention)
131
What are the 4 noteworthy community environmental health hazards
Hazardous waste sites, air pollution, nuclear facilities, and drinking water
132
What are 5 methodological difficulties associated with waste sites
Complex mixture of substances, studies may not adequately control for confounding factors, long-term effects of exposure hard to measure, effects of low-level exposures are difficult to show, and small study samples
133
What are 4 methodological difficulties associated with smoking
Small increases in risk of death from passive smoking difficult to show, short-term vs. long-term exposure, exposure to cigarette smoke from many sources, and long latency period between exposure to cigarette smoke and onset of disease
134
What are nuclear facilities
Weapons production plants, test sites, and nuclear power plants
135
What are 7 sources of groundwater contamination
Industrial facilities, new human habitation, runoff from growing urbanized areas, pathogenic microorganisms, pesticides, radioactivity, etc.
