Epidemiology (final exam) Flashcards
Includes demography and standardization, smoking cessation, and epidemiology of infectious disease
1
Q
Define
Demography
A
The study of populations, especially with reference to
- size and density,
- fertility,
- mortality,
- growth,
- age distribution,
- migration, and
- vital statistics;
and the interaction of all these with social and economic conditions
2
Q
What factors determine population size?
A
- Birth
- Death
- Migration
3
Q
How is population size calculated?
A
P2 = P1 + B – D + IM – EM, where
- P1 is the previously recorded population size
- B is the number of births
- D is the number of deaths
- IM are immigrants (migrants into the area)
- EM are emigrants (migrants out of the area)
4
Q
How do natural population increase and decrease occur?
A
- Increase: when births outnumber deaths
- Decrease: when deaths outnumber births
5
Q
How can population growth rates be described?
A
- Annual percentage increase
- Population doubling time (PDT)
6
Q
Define
Population doubling time
A
The number of years it will take for the population to double in size
7
Q
How is PDT calculated?
A
PDT = 70/annual percentage increase
(annual percentage increase is kept as a percentage, i.e. if it’s 2.3%, it is left as 70/2.3, not 70/0.023)
8
Q
What is the PDT for a population growing at 3% per annum?
A
PDT = 70/3%
= 23.33
≈ 23 years
9
Q
What are sources of demographic information?
A
- Censuses
- Population registers
- Registration of vital events
- Sample household survey
- Governmental and private record systems
10
Q
What are the types of censuses?
A
- Decennial: a poll count on a 100% sample, held every 10 years
- Midcensus: a poll count on a 10% sample, held every 10 years between full censuses
11
Q
What are the limitations of censuses?
A
- Costly
- Slow
- Censuses in developing countries are likely to be incomplete and inaccurate
12
Q
What is a population register?
A
More or less equivalent to a continuous census
13
Q
What kinds of events are recorded in vital event registers?
A
- Births
- Deaths
- Marriages
- Divorces
- Stillbirths
- Adoptions
14
Q
What systems are included in governmental/private record systems?
A
- Health services
- Education
- Armed forces
- Social security
- Insurance
15
Q
What are the types of population data?
A
- Population size
- Mortality (death) rates
- Fertility: birth rate, fertility rate
- Residential mobility
- Population composition
- Geographic distribution of the population
- Population characteristics: marital and family status, education, occupation, income
16
Q
Why are age and sex composition chosen to make population pyramids?
A
These two factors influence to pattern of mortality and natality more than any other factors
17
Q
What are the common shapes of population pyramids?
A
- Spike
- Wedge
- Barrel
18
Q
What are the characteristics of a spike-shaped population pyramid?
A
- Wide base with a rapidly narrowing apex
- High birth rate and high death rate at all ages
- Low total growth rate
- Characteristic of an underdeveloped country in primitive demographic equilibrium
19
Q
Which population pyramid shape is typical of an underdeveloped country in a primitive demographic equilibrium?
A
Spike shape
20
Q
What are the characteristics of a wedge-shaped population pyramid?
A
- Wide base and gradually narrowing apex
- High birth rate and low death rate
- High total growth rate
- Characteristic of a country in demographic transition with a rapidly growing population
21
Q
Which population pyramid shape is typical of a country in demographic transition?
A
Wedge shape
22
Q
What challenges face a country with a wedge-shaped population pyramid?
A
- Imbalance of its dependency ratio
- Severe socioeconomic stress
23
Q
What are the characteristics of a barrel-shaped population pyramid?
A
- Narrow base with little further narrowing towards the apex
- Low birth rate and low death rate
- Characteristic of developed country in an evolved demographic equilibrium
24
Q
Which population pyramid shape is typical of developed countries in an evolved demographic equilibrium?
A
Barrel shape
25
What are the factors affecting mortality?
* Age structure (the **main determinant**)
* Environment
* Economic development
* Technological advance
* Medical services/development of public health
26
What are the common causes of death in primitive, developing, and developed societies?
* Primitive: plague, cholera, typhus, smallpox (formerly)—i.e. epidemic infectious diseases
* Developing: dysentery, tuberculosis, pneumonia—i.e. endemic infectious diseases
* Developed/modern: chronic diseases—mainly cancer and ischemic heart disease
27
What kinds of death rates can be compared for populations?
* Crude death rate
* Age-specific death rate
* Standardized death rate
* Standardized mortality ratio (SMR)
28
Why is comparing crude death rates not advisable?
The differences could be due only to the demographic differences between the populations, e.g. proportion of elderly people
29
How is the difference in age composition of populations adjusted for when comparing death rates?
Standardization
30
What are the methods of standardization for death rates?
* Direct: using a standard population for age distributions (the **number of people** in each age tier)
* Indirect (SMR): using a standard population for age-specific **death rates** (the death rates themselves)
31
When is direct standardization used?
To compare large populations
32
What is a standard population?
Any population chosen to provide the data for standardized death rates. It can be either of the populations being compared, or one entirely unrelated
33
What are the advantages of direct age standardization?
* Consistency: if the age-specific death rates in population A are all higher than those in population B, this will still be reflected in the standardized rates
* Directly standardized rates can be compared over time if the same standard population is used
34
What are the limitations of direct age standardization?
* Data on death rates by age must be available
* Not suitable for small populations, as the age-specific rates are based on small numbers and thus very unstable
35
What is indirect standardization?
Adjusting for differences in age by calculating the number of deaths **expected** in the population if it had the same mortality experience as a **reference** population
36
What are the benefits of using a SMR?
* Easier to use
* Permits for statistical calculations (confidence interval)
* The information necessary is more easily available than for direct standardization
36
When is SMR more useful than direct standardization?
* Small populations
* When the age-specific death rates are unknown
37
How is SMR calculated?
SMR = (observed deaths × 100)/expected deaths
38
How are expected deaths calculated for SMR?
Multiplying the age-specific death rate for the reference population by the age range population of the population under study
39
How is SMR interpreted? What does an SMR of 120 mean? What does an SMR of 60% mean?
* SMR = 100: the study population has the same mortality rate as the reference population
* SMR > 100: the study population has a mortality rate higher than the reference population
* SMR < 100: the study population has a mortality rate lower than the reference population
SMR of 120 means the study population's mortality rate is 20% higher than the reference population's
SMR of 60 means the study population's mortality rate is 50% lower than the reference population's
40
What is the effect of chronic nicotine exposure on the central nervous system?
* Neuroadaptation: an increase in the number of brain nicotinic cholinoceptors
* Changes in gene expression and neural plasticity
41
What is the biology of nicotine addiction and the role of dopamine?
1. Nicotine stimulates dopamine release
2. Dopamine triggers pleasurable feelings
3. Repeat administration to experience pleasure
4. Development of tolerance and increase in the needed dose
42
What are the steps in the dopamine reward pathway?
1. Nicotine enters the brain
2. Nicotine binds to α4β2 nicotinic receptors
3. Stimulation of α4β2 receptors leads to stimulation of the ventral tegmental area (VTA)
4. The VTA has dopaminergic neurons that extend to the nucleus accumbens
5. The nucleus accumbens and VTA ultimately stimulate the prefrontal cortex
6. The prefrontal cortex begins the cascade of reactions resulting in the neuroendocrine and visceral responses to reward
43
What are the biologic factors for tobacco addiction?
* Desire for the direct pharmacologic actions of nicotine
* Relief of withdrawal symptoms
* Learned associations and behavior
44
What are some reasons smokers provide for their continued smoking?
* Pleasure
* Arousal
* Enhanced vigilance
* Improved performance
* Relief of anxiety or depression
* Appetite suppression
* Control of body weight
45
What are the symptoms of nicotine withdrawal?
* Depression
* Insomnia
* Irritability, frustration, and anger
* Anxiety
* Difficulty concentrating
* Restlessness
* Increased appetite and weight gain
* Decreased heart rate
* Cravings for nicotine
46
What is the onset and duration of nicotine withdrawal symptoms?
* Symptoms peak 24–48 hours after quitting
* Symptoms subside within 2–4 weeks
47
What are the immediate benefits to smoking cessation (< 1 week)
* Easier breathing due to relaxation of bronchial tubes
* Energy levels increase
48
What are the medium-term benefits to smoking cessation (months–1 year)
**1 month**
* Skin appearance improves due to improved skin perfusion
**3–9 months**
* Cough, wheezing, and breathing problems improve
* Lung function increases by up to 10%
**1 year**
* Risk of heart attack falls to half that of a smoker
49
What are the long-term benefits to smoking cessation (years)
**10 years**
* Risk of lung cancer falls to half that of a smoker
**15 years**
* Risk of heart attack falls to the same level as a person who has never smoked
50
How is smoking cessation managed?
* Behavioral therapy, **AND**
* Nicotine replacement therapy **OR** nicotinic partial agonists
51
What is nicotine replacement therapy (NRT)?
Providing the smoker with nicotine without using tobacco, thereby relieving symptoms of nicotine withdrawal
52
What is the principle behind NRT?
* Many of the difficulties in sustained smoking cessation are due to nicotine withdrawal
* NRT attenuates the severity of withdrawal, making it easier for ex-smokers to cope with abstinence
* When combined with unlearning the habitual elements of smoking addiction, this results in higher chances of success
53
What are the kinds of NRT?
* Nicotine patches
* Nicotine gum
* Nicotine lozenges
54
What is the typical length of nicotine patch treatment?
12 weeks
55
How long do the effects of nicotine patches last?
16–24 hours
56
What is the typical treatment regime of nicotine patches?
21–24 mg/24 h, 14 mg/24 h, 7 mg/24 h
Administered for 6, 3, and 3 weeks, respectively, **or** 8, 2, and 2 weeks
57
What are the contraindications and precautions of using nicotine patches?
* Pregnant or breastfeeding women
* Smokers with cardiovascular conditions
* Smokers using other NRT products
* Children
* Non-smokers
* Smokers of fewer than 10 cigarettes a day
58
How should nicotine patches be applied?
* Apply to non-hairy, clean, dry skin
* Rotate between sites to prevent irritation
* Choose a flat surface
* Avoid joints or skin folds
* Replace at the same time everyday
* Do not smoke while using the patch
59
What is the rationale behind using 24-hour nicotine patches, when 16-hour patches (giving 8 nicotine-free hours) exist?
Many dependent smokers wake up at night to smoke or otherwise cannot withstand being nicotine free overnight
60
When are nicotine lozenges preferred over nicotine gum?
Smokers with dentures or poor dentition
61
What is the best course of treatment for smokers with ischemic heart disease?
Beginning with behavioral therapy and only using NRT if this fails
62
What is varenicline?
A partial agonist of the α4β2 nicotinic cholinoceptor
## Footnote
(In the presence of actual nicotine, it acts as an antagonist)
63
What is the usual treatment regimen of varenicline?
Week 1: 0.5 mg once daily for 3 days, then 0.5 mg twice daily for 4 days
Then: 1 mg twice daily for 8–12 weeks
64
What are the contraindications of varenicline?
* Should not be used in those under 18, as it has not been tested on children
* Varenicline may pass into breast milk
* Lower doses are advisable for people with kidney problems
* Has not been tested for teratogenicity and so should not be used by pregnant women
* Caution is advised for patients with history of psychiatric illness
65
What are the side effects of varenicline?
* Vomiting and nausea
* Headaches
* Sleep disturbances and atypical dreams
* Flatulence (wind)
* Dysgeusia (changes in how food tastes)
* Constipation
* Suicide ideation
66
What is the main use of bupropion (Zyban)?
Atypical antidepressant (norepinephrine–dopamine reuptake inhibitor)
67
What are the side effects of bupropion?
* Insomnia
* Agitation
* Dry mouth
* Headache
* Lowering of the seizure threshold
68
How does bupropion function in smoking cessation?
It prevents dopamine and norepinephrine reuptake, enhancing CNS noradrenergic and dopaminergic release
69
What are the outcomes of the Fagerstorm scoring system?
* 7–10: highly dependent
* 4–6: moderately dependent
* < 4: minimally dependent
70
What are the questions asked in the Fagerstorm scoring system?
1. How soon after waking up the person smokes
2. If the person can resist smoking in places where smoking is inappropriate (e.g. hospitals, schools)
3. Which cigarette the person treasures most: the first one in the morning, or any other
4. How many cigarettes the person smokes
5. If the person smokes more during the first few hours after waking up
6. If the person still smokes when badly ill
71
# Define
Acute disease
Disease in which symptoms develop rapidly and that runs its course quickly
72
# Define
Chronic disease
Disease with usually mild symptoms that develop slowly and last a long time
73
# Define
Subacute disease
Disease with time course and symptoms between acute and chronic
74
# Define
Asymptomatic disease
Disease without symptoms
| (Shocker, I know)
75
# Define
Communicable disease
Disease transmitted from one host to another
76
# Define
Latent disease
Disease that appears a long time after infection
77
# Define
Contagious disease
Communicable disease that is easily spread
78
# Define
Noncommunicable disease
Disease arising from outside of hosts or from opportunistic pathogen
79
# Define
Local infection
Infection confined to a small region of the body
80
# Define
Systemic infection
Widespread infection in many systems of the body; often travels in the blood or lymph
81
# Define
Focal infection
Infection that serves as a source of pathogens for infections at other sites in the body
82
# Define
Primary infection
Initial infection within a given patient
83
# Define
Secondary infection
Infections that follow a primary infection; often by opportunistic pathogens
84
What is the importance of studying the epidemiology of communicable diseases?
* Changes of the pattern of infectious disease
* Discovery of new infections
* The possibility that some chronic diseases have an infective origin
85
# Define
Hyperendemic
A disease that is constantly present at high incidence and/or prevalence rates and affects all age groups equally
86
# Define
Holoendemic
A disease with a high level of infection beginning early in life and affecting most of the child population, while the adult population shows evidence of the disease much less, e.g. malaria
87
What is an example of a holoendemic disease?
Malaria
88
# Define
Sporadic disease
A disease where cases are few and separated widely in time and place, with irregular, haphazardly and generally infrequent incidence, e.g. polio, meningococcal meningitis, tetanus
89
What are examples of sporadic diseases?
* Polio
* Meningococcal meningitis
* Tetanus
90
# Define
Exotic disease
A disease that is imported into a country where it normally does not occur, e.g. rabies in the UK, yellow fever in India
91
What are examples of exotic diseases in specific countries?
* Rabies: UK
* Yellow fever: India
92
# Define
Nosocomial infection
A hospital-acquired infection originating in a patient while in a hospital or other healthcare facility. Must be a disorder **unrelated** to the patient's primary condition, e.g. infection of surgical wounds, hepatitis B, UTIs
93
# Define
Opportunistic infection
Infection by organisms that take the opportunity presented by a defect in host defense systems to infect the host and cause disease, e.g. herpes simplex virus, cytomegalovirus, and tuberculosis _in AIDS patients_
94
What are examples of opportunistic infections in AIDS patients?
* Herpes simplex virus
* Cytomegalovirus
* *Mycobacterium tuberculosis*
95
# Define
Iatrogenic disease
Adverse consequences of a preventive, diagnostic, or therapeutic regimens or procedures that cause impairment, handicap, disability, or death **in relation to** a physician's professional activity, e.g. hepatitis B infection following blood transfusion
96
# Define
Eradication
Termination of all transmission of infection by the extermination of the infectious agent through surveillance and containment
97
# Define
Elimination
Eradication of a disease from a large geographic region, e.g. polio, measles, leprosy, diphtheria
98
What is an example of an eradicated infection?
Smallpox
99
What are examples of infections that are amenable to elimination
* Measles
* Diphtheria
* Leprosy
* Polio
100
# Define
Case
A person in the population or study group identified as having the particular disease, disorder, or condition under investigation
101
# Define
Index case
The first person with the condition who comes to the attention of public health authorities
102
# Define
Primary case
A person who acquires the disease from an exposure
103
# Define
Secondary case
A person who acquires the disease from an exposure to the primary case
104
What is the secondary attack rate? How is it calculated?
The number of exposed persons developing the disease within the range of the incubation period, following exposure to the primary case
SAR = (# of people developing the disease within the range of incubation period) × 100 / (total # of exposed)
105
# Define
Virulence
The disease evoking power of a microorganism in a given host
(number of deaths/number with disease) × 100
106
# Define
Infectivity
The power of a microorganism to establish infection in a given host
(number infected/number susceptible) × 100
107
# Define
Pathogenicity
(number with clinical disease/number infected) × 100
108
What are the types of influenza viruses?
* Type A
* Type B
* Type C
109
What are the characteristics of type A influenza?
* Affects both humans and animals
* Divided into subtypes based on the presence of two surface proteins: hemagglutinin (H) and neuraminidase (N)
* Two commonly circulating strains: H1N1, H3N2
110
What are the characteristics of type B influenza?
* Predominantly affects humans
* Two lineages: Victoria and Yamagata
111
What are the characteristics of type C influenza?
* Rarely reported in humans
* Cases are usually subclinical
112
How do surface antigens of influenza viruses change?
* Antigenic drift: minor changes associated with annual outbreaks or epidemics. This is why vaccines must be updated yearly
* Antigenic shift: major changes resulting in new subtypes with a new H protein (and sometimes new N). New subtypes may cause pandemics
113
What are the groups recommended to be vaccinated for influenza?
**People at risk of complications**
* Pregnant women (highest priority)
* Children aged 6 months to 5 years
* children aged 6–23 months take priority, then
* children aged 2–5 years
* Elderly people (≥ 65 years)
* People with underlying health conditions (e.g. diabetes, asthma, chronic heart or lung disease, HIV/AIDS)
* International travelers who belong to any of the above groups
**People at high risk of exposure and transmission**
* Healthcare workers
114
What are the components of the trivalent influenza vaccine (TIV)?
* H1N1
* H3N2
* Yamagata **OR** Victoria lineage influenza B
115
What are the components of the quadrivalent influenza vaccine (QIV)?
* H1N1
* H3N2
* Yamagata **AND** Victoria lineage influenza B
116
What is the seasonality pattern of influenza viruses?
* Northern hemisphere: November–March
* Southern hemisphere: May–October
* Tropics: year-round transmission with several peaks
117
How is penumococcus transmitted?
Aerosol spread from person to person
118
What is the typical course of pneumococcal infection?
Local spread to tissues or invasion of the circulatory torrent and hematogenous spread
119
Under which circumstances is pneumococcal colonization possible?
1. Colonization with a pneumococcal strain against which immunity has not been established
2. Alteration of the natural barriers or host immune system
120
What types of diseases can pneumococcus cause?
**Non-invasive**
* Acute otitis media
* Sinusitis
* Conjunctivitis
* Bronchitis
* Pneumonia
**Invasive**
* Bacteremia
* Bacteremic pneumonia/empyema (accumulation of pus in pleura)
* Sepsis
* Meningitis
* Peritonitis
* Arthritis
* Osteomyelitis
121
What are the at-risk groups for pneumococcus?
**Immunocompetent children**
* Chronic pulmonary disease: asthma, bronchopulmonary dysplasia, cystic fibrosis, A1AT deficiency, bronchiectasis
* Chronic heart disease
* Down syndrome
* Diabete mellitus
* Chronic liver disease
* Subarachnoid space fistulas (inflammation of the pleura)
* Children with cochlear implants (hearing aids)
**Children with anatomic or functional asplenia (absence of spleen)**
* Sickle-cell anemia and other hemoglobinopathies
* Congenital or acquired asplenia or splenic dysfunction
**Immunocompromised children**
* HIV/AIDS patients
* Primary immunodeficiency (**except** isolated IgA deficiency)
* Chronic kidney failure and nephritic syndrome
* Diseases that require treatment with immunosuppressant drugs or radiotherapy (e.g. leukemia, lymphoma, bone marrow or organ transplant)
122
Which two at-risk groups have the highest incidence of invasive pneumococcal disease (IPD)?
* HIV/AIDS patients
* Hematological cancer patients
Both have a 20-fold increased risk
123
What characterizes tobacco dependence?
* A physiologic dependence due to nicotine addiction
* A behavioral pattern of using tobacco
124
What is the addictive substance in tobacco?
Nicotine
125
What is the substance that is introduced to the lungs during smoking?
Tar droplets, containing nicotine among other things
126
How much nicotine is usually absorbed systemically from a single cigarette?
1 mg
127
What dose of nicotine per day can facilitate addiction to tobacco products?
5 mg
128
How long does it take for nicotine to reach the brain if inhaled (e.g. by smoking)
15–20 seconds
129
What is the difference in systemic levels of nicotine when orally administered (e.g. from smokeless tobacco) compared to traditional smoking?
Nicotine levels from oral administration rise more gradually and are sustained for longer
130
Where is most of the nicotine absorbed from tobacco metabolized?
Liver
131
What is the typical product of nicotine metabolism?
Cotinine
132
Where is nicotine excreted?
Kidneys
133
Where does nicotine accumulate other than in the kidneys (and urine) and liver?
* Amniotic fluid
* Breast milk
* The blood and urine of nursing infants whose mothers use tobacco
134
What is the half-life of nicotine?
2 hours
135
What are the target organs of nicotine?
* Brain
* Cardiovascular system
* Peripheral nervous system
* Gastrointestinal system
136
What are the daily tasks commonly accompanied by smoking?
* Drinking coffee
* Waking up
* Eating
* Watching television
137
When, in relation to nicotine levels, does a chronic smoker typically smoke their next cigarette?
When their blood nicotine levels fall below a threshold, causing withdrawal symptoms. This threshold changes over the course of the day
138
What is the typical amount of nicotine per day that a chronic smoker consumes?
10–40 mg
139
When is a person with influenza contagious?
Up to 1 day before symptoms begin and 2 weeks after symptoms end
140
What are the modes of influenza vaccination?
* Injection
* Nasal spray
141
How often per year are influenza vaccines updated?
Twice
142
What is the effect of the influenza vaccine on the risk of infection?
Reduces it by half, from 10% to 5%
143
In which groups is the influenza vaccine contraindicated?
* Infants under 6 months
* People with severe egg allergy
* People with history of Guillain–Barré syndrome
