Epidemiology

In the definition of epidemiology, "distribution" refers to EXCEPT:

• Who

• When

• Where

• Why

In the definition of epidemiology, "determinants" generally includes EXCEPT:

• Agents

• Causes

• Control measures

• Risk factors

• Sources

Epidemiology, as defined in this lesson, would NOT include which of the following activities?

• Describing the demographic characteristics of persons with acute aflatoxin poisoning in District A

• Prescribing an antibiotic to treat a patient with community-acquired methicillin-resistantStaphylococcus aureus infection

• Comparing the family history, amount of exercise, and eating habits of those with and without newly diagnosed diabetes

• Recommending that a restaurant be closed after implicating it as the source of a hepatitis A outbreak

John Snow's investigation of cholera is considered a model for epidemiologic field investigations because it includes the following EXCEPT:

• Biologically plausible hypothesis

• Comparison of a health outcome among exposed and unexposed groups

• Multivariate statistical model

• Spot map

• Recommendation for public health action

Public health surveillance does NOT include which of the following activity:

• Diagnosing whether a case of encephalitis is actually due to West Nile virus infection

• Soliciting case reports of persons with symptoms compatible with SARs from local hospitals

• Creating graphs of the number of dog bites by week and neighborhood

• Writing a report on trends in seat belt use to share with the state legislature

• All of the above

• None of the above

The hallmark feature of an analytic epidemiologic study is:

• Use of an appropriate comparison group

• Laboratory confirmation of the diagnosis

• Publication in a peer-reviewed journal

• Statistical analysis using logistic regression

A number of passengers on a cruise ship from Puerto Rico to the Panama Canal have recently developed a gastrointestinal illness compatible with norovirus (formerly called Norwalk-like virus). Testing for norovirus is not readily available in any nearby island, and the test takes several days even where available. Assuming you are the epidemiologist called on to board the ship and investigate this possible outbreak, your case definition should include, at a minimum:

• Clinical criteria, plus specification of time, place, and person

• Clinical features, plus the exposure(s) you most suspect

• Suspect cases

• The nationally agreed standard case definition for disease reporting

Compare food histories between persons with Staphylococcus food poisoning and those without

• Distribution

• Determinants

• Application

Compare frequency of brain cancer among anatomists with frequency in general population

• Distribution

• Determinants

• Application

Mark on a map the residences of all children born with birth defects within 2 miles of a hazardous waste site

• Distribution

• Determinants

• Application

Graph the number of cases of congenital syphilis by year for the country

• Distribution

• Determinants

• Application

Recommend that close contacts of a child recently reported with meningococcal meningitis receive Rifampin

• Distribution

• Determinants

• Application

Tabulate the frequency of clinical signs, symptoms, and laboratory findings among children with chickenpox in Cincinnati, Ohio

• Distribution

• Determinants

• Application

Essay entitled “On Airs, Waters, and Places,” suggested that environmental and host factors such as behaviors

• Hippocrates

• John Graunt

• John Snow

first to quantify patterns of birth, death, and disease occurrence, noting disparities between males and females, high infant mortality, urban/rural differences, and seasonal variations

• John Graunt

• John Snow

• William Farr

Father of modern vital statistics and surveillance

• William Farr

• John Snow

• John Graunt

Father of field epidemiology

• John Graunt

• John Snow

• William Farr

Study linking lung cancer to smoking

• Doll and Hill

• John Snow

• Kannel

Reviewing reports of test results for Chlamydia trachomatis from public health clinics

• Public health surveillance

• Field investigation

• Analytic studies

• Evaluation

• Linkages

• Policy development

Meeting with directors of family planning clinics and college health clinics to discuss Chlamydia testing and reporting

• Public health surveillance

• Analytic studies

• Evaluation

• Field investigation

• Linkages

• Policy development

Developing guidelines/criteria about which patients coming to the clinic should be screened (tested) for Chlamydia infection

• Public health surveillance

• Field investigation

• Analytic studies

• Evaluation

• Linkages

• Policy development

Interviewing persons infected with Chlamydia to identify their sex partners

• Public health surveillance

• Field investigation

• Analytic studies

• Evaluation

• Linkages

• Policy development

Conducting an analysis of patient flow at the public health clinic to determine waiting times for clinic patients

• Public health surveillance

• Analytic studies

• Evaluation

• Linkages

• Policy development

• Field investigation

Comparing persons with symptomatic versus asymptomatic Chlamydia infection to identify predictors

• Public health surveillance

• Field investigation

• Evaluation

• Linkages

• Policy development

• Analytic studies

Comparing numbers and rates of illness in a community, rates are preferred for

• Conducting surveillance for communicable diseases

• Deciding how many doses of immune globulin are needed

• Estimating subgroups at highest risk

• Telling physicians which strain of influenza is most prevalent

For the cruise ship scenario described in Question 7, how would you display the time course of the outbreak?

• Endemic curve

• Epidemic curve

• Seasonal trend

• Secular trend

For the cruise ship scenario described in Question 7, if you suspected that the norovirus may have been transmitted by ice made or served aboard ship, how might you NOT display "place"?

• Spot map by assigned dinner seating location

• Spot map by cabin

• Shaded map of United States by state of residence

• Shaded map by whether passenger consumed ship's ice or no

When analyzing surveillance data by age, which of the following age groups is preferred?

• 1-year age groups

• 5-year age groups

• 10-year age groups

• Depends on the disease

A study in which children are randomly assigned to receive either a newly formulated vaccine or the currently available vaccine, and are followed to monitor for side effects and effectiveness of each vaccine, is an example of which type of study?

• Cohort

• Case-control

• Clinical trial

• Cross Sectional

The Iowa Women's Health Study, in which researchers enrolled 41,837 women in 1986 and collected exposure and lifestyle information to assess the relationship between these factors and subsequent occurrence of cancer, is an example of which type(s) of study?

• Cohort

• Case-control

• Clinical trial

• Cross Sectional

British investigators conducted a study to compare measles-mumps-rubella (MMR) vaccine history among 1,294 children with pervasive development disorder (e.g., autism and Asperger's syndrome) and 4,469 children without such disorders. (They found no association.) This is an example of which type(s) of study?

• Cohort

• Case-control

• Clinical trial

• Cross Sectional

A cohort study differs from a case-control study in that:

• Subjects are enrolled or categorized on the basis of their exposure status in a cohort study but not in a case-control study

• Subjects are asked about their exposure status in a cohort study but not in a case-control study

• Cohort studies require many years to conduct, but case-control studies do not

• Cohort studies are conducted to investigate chronic diseases, case-control studies are used for infectious diseases

A key feature of a cross-sectional study EXCEPT:

• It usually provides information on prevalence rather than incidence

• It is limited to health exposures and behaviors rather than health outcomes

• It is more useful for descriptive epidemiology than it is for analytic epidemiology

• It is synonymous with survey

The epidemiologic triad of disease causation refers to

• Agent, host, environment

• Time, place, person

• Source, mode of transmission, susceptible host

• John Snow, Robert Koch, Kenneth Rothman

A reservoir of an infectious agent can be:

• An asymptomatic human

• A symptomatic human

• An animal

• The environment

• All of the above

Indirect transmission includes which of the following EXCEPT?

• Droplet spread

• Mosquito-borne

• Foodborne

• Doorknobs or toilet seats

Disease control measures are generally directed at which of the followingEXXCEPT ?

• Eliminating the reservoir

• Eliminating the vector

• Eliminating the host

• Interrupting mode of transmission

• Reducing host susceptibility

Disease 1: usually 40–50 cases per week; last week, 48 cases

• Endemic

• Outbreak

• Pandemic

• Sporadic

Disease 2: fewer than 10 cases per year; last week, 1 case

• Endemic

• Outbreak

• Pandemic

• Sporadic

Disease 3: usually no more than 2–4 cases per week; last week, 13 cases

• Endemic

• Outbreak

• Pandemic

• Sporadic

A propagated epidemic is usually the result of what type of exposure?

• Point source

• Continuous common source

• Intermittent common source

• Person-to-person

In a state that did not require varicella (chickenpox) vaccination, a boarding school experienced a prolonged outbreak of varicella among its students that began in September and continued through December. To calculate the probability or risk of illness among the students, which denominator would you use?

• Number of susceptible students at the ending of the period (i.e., June)

• Number of susceptible students at the midpoint of the period (late October/early November)

• Number of susceptible students at the beginning of the period (i.e., September)

• Average number of susceptible students during outbreak

Many of the students at the boarding school, including 6 just coming down with varicella, went home during the Thanksgiving break. About 2 weeks later, 4 siblings of these 6 students (out of a total of 10 siblings) developed varicella. The secondary attack rate among siblings was, therefore,:

• 4 ⁄ 6

• 4 ⁄ 10

• 4 ⁄ 16

• 6 ⁄ 10

Investigators enrolled 100 diabetics without eye disease in a cohort (follow-up) study. The results of the first 3 years were as follows:
Year 1: 0 cases of eye disease detected out of 92; 8 lost to follow-up
Year 2: 2 new cases of eye disease detected out of 80; 2 had died; 10 lost to follow-up
Year 3: 3 new cases of eye disease detected out of 63; 2 more had died; 13 more lost to follow-up
The person-time incidence rate is calculated as:

• 5 ⁄ 100

• 5 ⁄ 63

• 5 ⁄ 235

• 5 ⁄ 250

Measure of risk

• Incidence

• Prevalence

Generally preferred for chronic diseases without clear date of onset

• Incidence

• Prevalence

Used in calculation of risk ratio

• Incidence

• Prevalence

Affected by duration of illness

• Incidence

• Prevalence

The best measure of association to use for these data is a/an:

• Food-specific attack rate

• Odds ratio

• Rate ratio

• Risk ratio

The best estimate of the association between wedding cake and illness is:

• 6.1

• 7.7

• 68.4

• 83.7

• 91.7

• 94.3

The attributable proportion for wedding cake is:

• 6.1%

• 7.7%

• 68.4%

• 83.7%

• 91.7%

• 94.3%

What is the incidence of disease during July?

• 3 ⁄ 700

• 4 ⁄ 700

• 5 ⁄ 700

• 8 ⁄ 700

Vaccine efficacy measures are:

• The proportion of vaccinees who do not get the disease

• 1 − the attack rate among vaccinees

• The proportionate reduction in disease among vaccinees

• 1 − disease attributable to the vaccine

To study the causes of an outbreak of aflatoxin poisoning in Africa, investigators conducted a case-control study with 40 case-patients and 80 controls. Among the 40 poisoning victims, 32 reported storing their maize inside rather than outside. Among the 80 controls, 20 stored their maize inside. The resulting odds ratio for the association between inside storage of maize and illness is:

• 3.2

• 5.2

• 12.0

• 33.3

The crude mortality rate in Community A was higher than the crude mortality rate in Community B, but the age-adjusted mortality rate was higher in Community B than in Community A. This indicates that:

• Investigators made a calculation error

• No inferences can be made about the comparative age of the populations from these data

• The population of Community A is, on average, older than that of Community B

• The population of Community B is, on average, older than that of Community A

public health surveillance includes which activities EXCEPT?

• Data collection.

• Data analysis.

• Data interpretation.

• Data dissemination.

• Disease control.

Current public health surveillance targets which of the following?

• Chronic diseases.

• Communicable diseases.

• Health-related behaviors.

• Occupational hazards.

• Presence of viruses in mosquitoes.

• All of the above

Public health surveillance can be described primarily as which of the following?

• A method to monitor occurrences of public health problems.

• A program to control disease outbreaks.

• A system for collecting health-related information.

• A system for monitoring persons who have been exposed to a communicable disease.

Common uses and applications of public health surveillance include which of the following?

• Detecting individual persons with malaria so that they can receive prompt and appropriate treatment.

• Helping public health officials decide how to allocate their disease control resources.

• Identifying changes over time in the proportion of children with elevated blood lead levels in a community.

• Documenting changes in the incidence of varicella (chickenpox), if any, after a law requiring varicella vaccination took effect.

• All of the above

Data collected through which of the following methods is NOT commonly used for surveillance?

• Vital registration.

• Randomized clinical trials.

• Disease notifications.

• Population surveys.

Vital statistics are important sources of data on which of the following?

• Morbidity.

• Mortality.

• Health-related behaviors.

• Injury and disability.

• Outpatient health-care usage.

Key sources of morbidity data include which of the following EXCEPT?

• Environmental monitoring data.

• Hospital discharge data.

• Laboratory results.

• Notifiable disease reports.

The list of diseases that a physician must report to the local health department is typically compiled by the…

• Local health department.

• State health department.

• Centers for Disease Control and Prevention (CDC).

• Council of State and Territorial Epidemiologists (CSTE).

• Medical licensing board.

Based on statistically valid sample.

• Notifiable disease surveillance

• Surveillance for consumer product-related injuries

• Both.

• Neither

Complete, unbiased reporting

• Notifiable disease surveillance

• Surveillance for consumer product-related injuries

• Both.

• Neither.

Evaluating and improving surveillance should address which of the following EXCEPT?

• Purpose and objectives of surveillance.

• Resources needed to conduct surveillance.

• Effectiveness of measures for controlling the disease under surveillance.

• Presence of characteristics of well-conducted surveillance.

Criteria for prioritizing health problems for surveillance include which of the following EXCEPT?

• Incidence of the problem.

• Public concern about the problem.

• Number of previous studies of the problem.

• Social and economic impact of the problem.

Watches for individual cases of disease of public health importance.

• Surveillance based on a specific case definition for a disease (e.g., listeriosis).

• Syndromic surveillance based on symptoms, signs, or other characteristics of a disease, rather than specific clinical or laboratory diagnostic criteria.

• Both.

• Neither

Watches for diseases that might be caused by acts of biologic or chemical terrorism.

• Surveillance based on a specific case definition for a disease (e.g., listeriosis).

• Syndromic surveillance based on symptoms, signs, or other characteristics of a disease, rather than specific clinical or laboratory diagnostic criteria.

• Both.

• Neither

Can watch for disease before a patient seeks care from a health-care provider.

• Surveillance based on a specific case definition for a disease (e.g., listeriosis).

• Syndromic surveillance based on symptoms, signs, or other characteristics of a disease, rather than specific clinical or laboratory diagnostic criteria.

• Both.

• Neither

Requires little effort on the part of the health department.

• Surveillance based on a specific case definition for a disease (e.g., listeriosis).

• Syndromic surveillance based on symptoms, signs, or other characteristics of a disease, rather than specific clinical or laboratory diagnostic criteria.

• Both

• Neither

Routine analysis of notifiable disease surveillance data at the state health department might NOT include looking at the number of cases of a disease reported this week …

• and during the previous 2–4 weeks.

• and the number reported during the comparable weeks of the previous 2–5 years.

• simultaneously by age, race, and sex of the patient.

• by county.

• by county, divided by each county's population (i.e., county rates).

One week, a state health department received substantially more case reports of a disease in one county than had been reported during the previous 2 weeks. No increase was reported in neighboring counties. Possible explanations for this increase include which of the following?

• An outbreak in the county.

• Batch reports.

• Duplicate reports.

• Increase in the county's population.

• Laboratory error.

• All of the above

The primary reason for preparing and distributing periodic surveillance summaries is which of the following?

• Document recent epidemiologic investigations.

• Provide timely information on disease patterns and trends to those who need to know it.

• Provide reprints ofMMWR articles, reports, and recommendations.

• Acknowledge the contributions of those who submitted case reports.

Surveillance detected 23 of 30 actual cases of a disease.

• Predictive value positive.

• Sensitivity.

• Specificity.

• Validity

Of 16 statistically significant aberrations (deviations from baseline) detected by syndromic surveillance, only one represented an actual outbreak of disease.

• Predictive value positive.

• Sensitivity.

• Specificity.

• Validity.

Initiating surveillance for a public health problem or adding a disease to the notifiable disease list is justified for which of the following reason?

• If it is a communicable disease with a high case-fatality rate.

• If the problem is new and systematically collected data are needed to characterize the disease and its impact on the public.

• If a program at CDC has recommended its addition to better understand national trends and patterns.

• all of the above

A state health department decides to strengthen its notifiable disease reporting. The one best action to take is to …

• allow reporting through use of the Internet.

• require more disease-specific forms from local health departments.

• ensure that all persons with a responsibility to report understand the requirements and reasons for reporting and how reports will be used.

• reduce the number of diseases on the list.

What is the likely relationship between mean, median, and mode of the distribution shown in Figure 2.12?

• Mean < median < mode

• Mean = median = mode

• Mean > median > mode

• Mode < mean and median, but cannot tell relationship between mean and median

The mode is the value that:

• Is midway between the lowest and highest value

• Occurs most often

• Has half the observations below it and half above it

• Is statistically closest to all of the values in the distribution

The median is the value that:

• Is midway between the lowest and highest value

• Occurs most often

• Has half the observations below it and half above it

• Is statistically closest to all of the values in the distribution

Is statistically closest to all of the values in the distribution

• Is midway between the lowest and highest value

• Occurs most often

• Has half the observations below it and half above it

• Is statistically closest to all of the values in the distribution

The geometric mean is the value that:

• Is midway between the lowest and highest value on a log scale

• Occurs most often on a log scale

• Has half the observations below it and half above it on a log scale

• Is statistically closest to all of the values in the distribution on a log scale

In epidemiology, the measure of central location generally preferred for summarizing skewed data such as incubation periods is the:

• Mean

• Median

• Midrange

• Mode

The measure of central location generally preferred for additional statistical analysis is the:

• Mean

• Median

• Midrange

• Mode

Which of the following is NOT considered measures of spread?

• Interquartile range

• Percentile

• Range

• Standard deviation

The measure of spread most affected by one extreme value is the:

• Interquartile range

• Range

• Standard deviation

• Mean

The interquartile range covers what proportion of a distribution?

• 25%

• 50%

• 75%

• 100%

The measure of central location most commonly used with the interquartile range is the:

• Arithmetic mean

• Geometric mean

• Median

• Midrange

• Mode

The measure of central location most commonly used with the standard deviation is the:

• Arithmetic mean

• Median

• Midrange

• Mode

The algebraic relationship between the variance and standard deviation is that:

• The standard deviation is the square root of the variance

• The variance is the square root of the standard deviation

• The standard deviation is the variance divided by the square root of n

• The variance is the standard deviation divided by the square root of n

Before calculating a standard deviation, one should ensure that:

• The data are somewhat normally distributed

• The total number of observations is at least 50

• The variable is an interval-scale or ratio-scale variable

• All of the above

Simply by scanning the values in each distribution below, identify the distribution with the largest standard deviation.

• 1, 10, 15, 18, 20, 20, 22, 25, 30, 39

• 1, 3, 8, 10, 20, 20, 30, 32, 37, 39

• 1, 15, 17, 19, 20, 20, 21, 23, 25, 39

• 41, 42, 43, 44, 45, 45, 46, 47, 48, 49

Given the area under a normal curve, which two of the following ranges are the same? (Circle the TWO that are the same.)

• From the 2.5th percentile to the 97.5th percentile

• From the 5th percentile to the 95th percentile

• From the 25th percentile to the 75th percentile

• From 1 standard deviation below the mean to 1 standard deviation above the mean

• None of the above

The primary use of the standard error of the mean is in calculating the:

• confidence interval

• error rate

• standard deviation

• variance

Tables and graphs are NOT important tools for which tasks of an epidemiologist?

• Data collection

• Data summarization (descriptive epidemiology)

• Data analysis

• Data presentation

A table in a report or manuscript should include EXCEPT:

• Title

• Row and column labels

• Footnotes that explain abbreviations, symbols, exclusions

• Source of the data

• Explanation of the key findings

In the following table, the total number of persons with the disease is:
Cases Controls Total
Exposed 22 12 34
Unexposed 3 13 16
Total 25 25 50

• 3

• 22

• 25

• 34

• 50

A table shell is the:

• Box around the outside of a table

• Lines ("skeleton") of a table without the labels or title

• Table with data but without the title, labels or data

• Table with labels and title but without the data

The best time to create table shells is:

• Just before planning a study

• As part of planning the study

• Just after collecting the data

• Just before analyzing the data

• As part of analyzing the data

Recommended methods for creating categories for continuous variables include:

• Basing the categories on the mean and standard deviation

• Dividing the data into categories with similar numbers of observations in each

• Dividing the range into equal class intervals

• Using categories that have been used in national surveillance summary reports

• Using the same categories as your population data are grouped

• All of the above

• None of the above

On an arithmetic-scale line graph, the x-axis and y-axis each should:

• Begin at zero on each axis

• Have labels for the tick marks and each axis

• Use the same tick mark spacing on the two axes

• All of the above

Which of the following shapes of a population pyramid is most consistent with a young population?

• Tall, narrow rectangle

• Short, wide rectangle

• Triangle base down

• Triangle base up

A frequency polygon differs from a line graph because a frequency polygon:

• Displays a frequency distribution; a line graph plots data points

• Can show percentages on the y-axis; a line graph cannot

• Cannot be used to plot data over time

• All of the above

Y-axis shows percentages from 0% to 100%

• Cumulative frequency curve

• Survival curve

• Both

• Neither

Plotted curve usually begins in the upper left corner

• Cumulative frequency curve

• Survival curve

• Both

• Neither

Plotted curve usually begins in the lower left corner

• Cumulative frequency curve

• Survival curve

• Both

• Neither

Horizontal line drawn from 50% tick mark to plotted curve intersects at median

• Cumulative frequency curve

• Survival curve

• Both

• Neither

Which of the following requires more than one variable?

• Frequency distribution

• One-variable table

• Pie chart

• Scatter diagram

• Simple bar chart

Compared with a scatter diagram, a dot plot:

• Is another name for the same type of graph

• Differ because a scatter diagram plots two continuous variables; a dot plot plots one continuous and one categorical variable

• Differ because a scatter diagram plots one continuous and one categorical variable; a dot plot plots two continuous variables

• Plots location of cases on a map

When creating a bar chart, the decision to use vertical or horizontal bars is usually based on:

• The magnitude of the data being graphed and hence the scale of the axis

• Whether the data being graphed represent numbers or percentages

• Whether the creator is an epidemiologist (who almost always use vertical bars)

• Which looks better, such as whether the label fits below the bar

Factors that influence a health department's decision whether or not to conduct a field investigation in response to one or more cases of disease include

• The nature of the disease

• The number of cases

• Resources available

• Health department's traditional attitude toward conducting field investigations

• All of the above

Use the following steps of an outbreak investigation for Question 5:
1. Analyze data by time, place, and person
2. Conduct a case-control study
3. Generate hypotheses
4. Conduct active surveillance for additional cases
5. Verify the diagnosis
6. Confirm that the number of cases exceeds the expected number
7. Talk with laboratorians about specimen collection

For an investigation of an outbreak, what is the logical conceptual order of the steps listed above?

• 1-2-3-4-5-6-7

• 5-6-4-1-2-3-7

• 6-5-3-1-2-7-4

• 6-5-7-4-1-3-2

200 cases of Marburg virus infection in several districts in Angola over several months (usually none)

• Cluster

• Epidemic

• Outbreak

40 cases ofSalmonella Enteritidis in 1 week traced to a single meal served at a cafeteria (usually none)

• Cluster

• Epidemic

• Outbreak

10 cases of cancer diagnosed over 2 years among residents of a single neighborhood (previous data not available)

• Cluster

• Epidemic

• Outbreak

A case definition during an outbreak investigation should NOT specify:

• Clinical features

• Time

• Place

• Person

• Hypothesized exposure

Common methods of identifying additional cases (expanding surveillance) as part of an outbreak investigation include:

• Advising the public through newspapers, TV, radio, and the health department's website to contact the local health department

• Asking case-patients who they were with at the time of exposure (if known)

• Sending a fax to healthcare providers

• Telephoning the infection control practitioners at local hospitals

• All of the above

• None of the above

A case report form devised for an outbreak investigation usually includes which of the following types of information?

• Identifying information

• Demographic information

• Clinical information

• Risk factor information

• Reporter, interviewer, or data abstractor information

• All of the above

• None of the above

A malfunctioning space heater was used each time the outside temperature dropped below freezing

At the Eclipse Restaurant, sodium nitrite was mistaken for table salt in the preparation of breakfast one morning only

Common cold passed from classmate to classmate

Possible explanations for a case that occurs substantially later than the other cases in an outbreak include:

• Similar but unrelated disease

• Secondary case

• Case with unusually long incubation period

• Time of exposure later than others

• Error in recording date

• All of the above

• None of the above

Which of the following may be useful in generating hypotheses in an outbreak setting?

• Review the literature

• Look at the descriptive epidemiology

• Look at the outliers

• Talk with the local health authorities

• Talk with a few of the case-patients

• Talk with subject matter experts

• All of the above

• None of the above

The key feature of an analytic (epidemiologic) study is

• Analysis by time, place, and person

• Calculation of a risk ratio or odds ratio

• Use of Epi Info to analyze the data

• Presence of a comparison group