EPIDEMIOLOGY CERTIFICATION
EVALUATION EXAMS BUNDLE 2026
COMPLETE QUESTIONS AND ANSWERS
⩥ measures of disease frequency. Answer: Prevalence
- # cases / total pop
- % with disease at one point in time
- no units
Cumulative incidence
- # new cases / pop at risk
- % who develop disease over given period of time
- no units
Incidence rate
- # new cases / (# persons at risk * time observed)
- number / person-years or number of persons at risk per year
- includes a measure of time
⩥ 3 main sources of epidemic. Answer: 1. point transmission
2. person-to-person transmission
,3. continuous transmission
⩥ why quantify disease?. Answer: -characterize disease patterns and
trends (rising level of obesity in US)
-detect epidemics (tsar's epidemic)
-identify cases for research (especially useful for rare diseases/cancers)
-evaluate prevention and control programs
-project health needs
⩥ 3 ways to quantify disease occurrence. Answer: 1. case counts
(numbers)
2. proportions (ratio: # of cases/some variant of ppl at risk)
3. rates (ratio: # of cases in a given time/people at risk and time) ~
velocity of the disease
⩥ case counts. Answer: -useful for investigating disease outbreaks
(epidemic that occurs suddenly and within a confined geographic area)
-epidemic curve: number of cases (y-axis) against time of consent of
disease (x-axis)
⩥ point source transmission. Answer: an epidemic in which all cases are
infected at the same time, usually from a single source or exposure. ie all
people infected at a picnic ate the same food
,⩥ person-to-person transmission (propagated epidemic). Answer: an
epidemic in which the causal agent is transmitted from person to person,
allowing the epidemic to propagate or spread. (ie influenza)
⩥ continous source transmission. Answer: an epidemic in which the
causal agent (ie polluted drinking water, spoiled food) infects people as
they come into contact with it over an extended period of time. (as in the
case of cholera discovered by John Snow)
ie. multi-state outbreak of Listeriosis linked to Cantaloupes from a farm
in CO
⩥ prevalence. Answer: amount of disease already present in a
population. best used to measure chronic diseases (ie diabetes)
-point prevalence is proportion of disease in a population at a point in
time
-period prevalence is proportion of disease in a population during a
period of time
⩥ cumulative incidence (risk). Answer: the likelihood (risk) that an
individual will develop a disease. commonly used to measure acute
diseases and chronic diseases
, ⩥ incidence rate. Answer: how fast new occurrences of disease arise.
best used to measure acute, short duration diseases and/or chronic
diseases in large populations over longer times
⩥ estimating prevalence from incidence rate. Answer: if a disease is rare
(very low prevalence) then prevalence is approximately equal to the
incidence rate times disease duration
this is because for rare diseases, the rate of incidence will approximately
equal the rate at which people either die or are cured.
Example: Coronary Heart Disease is decreasing in prevalence over time.
Why? Mortality rate of ppl with CHD is going down due to improved
treatments so disease duration has increased. Incidence rate is decreasing
because we are effectively preventing CHD by modifying health
behaviors (known risk factors). Prevalence is approx equal to incidence
rate * disease duration (for rare diseases)
⩥ estimating cumulative incidence from incidence rate. Answer: If
incidence rate is low (IR*time<10%) then cumulative incidence ~
IR*time
if incidence rate is high then cumulative incidence = 1-e^(-IR*time)
EVALUATION EXAMS BUNDLE 2026
COMPLETE QUESTIONS AND ANSWERS
⩥ measures of disease frequency. Answer: Prevalence
- # cases / total pop
- % with disease at one point in time
- no units
Cumulative incidence
- # new cases / pop at risk
- % who develop disease over given period of time
- no units
Incidence rate
- # new cases / (# persons at risk * time observed)
- number / person-years or number of persons at risk per year
- includes a measure of time
⩥ 3 main sources of epidemic. Answer: 1. point transmission
2. person-to-person transmission
,3. continuous transmission
⩥ why quantify disease?. Answer: -characterize disease patterns and
trends (rising level of obesity in US)
-detect epidemics (tsar's epidemic)
-identify cases for research (especially useful for rare diseases/cancers)
-evaluate prevention and control programs
-project health needs
⩥ 3 ways to quantify disease occurrence. Answer: 1. case counts
(numbers)
2. proportions (ratio: # of cases/some variant of ppl at risk)
3. rates (ratio: # of cases in a given time/people at risk and time) ~
velocity of the disease
⩥ case counts. Answer: -useful for investigating disease outbreaks
(epidemic that occurs suddenly and within a confined geographic area)
-epidemic curve: number of cases (y-axis) against time of consent of
disease (x-axis)
⩥ point source transmission. Answer: an epidemic in which all cases are
infected at the same time, usually from a single source or exposure. ie all
people infected at a picnic ate the same food
,⩥ person-to-person transmission (propagated epidemic). Answer: an
epidemic in which the causal agent is transmitted from person to person,
allowing the epidemic to propagate or spread. (ie influenza)
⩥ continous source transmission. Answer: an epidemic in which the
causal agent (ie polluted drinking water, spoiled food) infects people as
they come into contact with it over an extended period of time. (as in the
case of cholera discovered by John Snow)
ie. multi-state outbreak of Listeriosis linked to Cantaloupes from a farm
in CO
⩥ prevalence. Answer: amount of disease already present in a
population. best used to measure chronic diseases (ie diabetes)
-point prevalence is proportion of disease in a population at a point in
time
-period prevalence is proportion of disease in a population during a
period of time
⩥ cumulative incidence (risk). Answer: the likelihood (risk) that an
individual will develop a disease. commonly used to measure acute
diseases and chronic diseases
, ⩥ incidence rate. Answer: how fast new occurrences of disease arise.
best used to measure acute, short duration diseases and/or chronic
diseases in large populations over longer times
⩥ estimating prevalence from incidence rate. Answer: if a disease is rare
(very low prevalence) then prevalence is approximately equal to the
incidence rate times disease duration
this is because for rare diseases, the rate of incidence will approximately
equal the rate at which people either die or are cured.
Example: Coronary Heart Disease is decreasing in prevalence over time.
Why? Mortality rate of ppl with CHD is going down due to improved
treatments so disease duration has increased. Incidence rate is decreasing
because we are effectively preventing CHD by modifying health
behaviors (known risk factors). Prevalence is approx equal to incidence
rate * disease duration (for rare diseases)
⩥ estimating cumulative incidence from incidence rate. Answer: If
incidence rate is low (IR*time<10%) then cumulative incidence ~
IR*time
if incidence rate is high then cumulative incidence = 1-e^(-IR*time)
