NR 503 EPI MIDTERM EXAM QUESTION BANK
Which of the following is a condition which may occur during the incubation
period?
Transmission of infection
The incubation period is defined as the interval from receipt of infection to the
time of onset of clinical illness. Accordingly, individuals may transmit infectious
agents during the incubation period as they show no signs of disease that would
enable the isolation of sick individuals by quarantine.
Chicken pox is a highly communicable disease. It may be transmitted by
direct contact with a person infected with the varicella-zoster virus (VZV).
The typical incubation time is between 10 to 20 days. A boy started school 2
weeks after showing symptoms of chicken pox including mild fever, skin rash,
and fluid-filled blisters. One month after the boy returned to school, none of
his classmates had been infected by VZV. The main reason was:
Contact was after infectious period
Subclinical infections were not yet detected
Disease was endemic in the class
The disease is spread by contact with an infected individual who can transmit the
agent (VZV) to immunologically naive persons during the incubation period and
for several days after onset of clinical illness. Since the boy started school 14 days
,after showing signs consistent with chicken pox, it is most likely that he was no
longer infectious.
The ability of a single person to remain free of clinical illness following
exposure to an infectious agent is known as:
Hygiene
Vaccination
Herd immunity
Immunity
Latency
Immunity is the capacity of a single individual to avoid disease susceptibility when
exposed to an infectious agent. Herd immunity is a population characteristic. For
certain diseases, individual immunity can be acquired by vaccination, but this is
not true for all infectious diseases.
Which of the following is characteristic of a single-exposure, common-vehicle
outbreak?
Long latency period before many illnesses develop
There is an exponential increase in secondary cases following initial
exposures
Cases include only those who have been exposed to sick persons
The epidemic curve has a normal distribution when plotted against the
logarithm of time
Wide range in incubation times for sick individuals
Single-exposure, common-vehicle outbreaks involve a sudden, rapid increase in
cases of disease that are limited to persons who share a common exposure.
,Additionally, few secondary cases develop among persons exposed to primary
cases. A histogram of the outbreak can plot the number of cases by time of disease
onset. In single-exposure, common-vehicle outbreaks, a log transformation of the
time of disease onset will often take on the characteristic shape of a normal
distribution (i.e., a bell curve) with the median incubation time found at the peak of
the curve.
What is the diarrhea attack rate in persons who ate both ice cream and pizza?
39/52
21/70
39/67
51/67
none of the above
The attack rate in this example is defined as the number of persons who develop
diarrhea divided by the total number of people at risk. In this example, the at-risk
group is those who have eaten both ice cream and pizza. Of these 52 persons, 39
developed diarrhea.
What is the overall attack rate in persons who did not eat ice cream?
30%
, 33%
35%
44%
58%
(14+9)/(40+30)= 33%
The attack rate is the number of persons with diarrhea (14 + 9) divided by the total
number of persons who did not eat ice cream (40 + 30).
Which of the food items (or combination of items) is most likely to be the
infective item(s)?
Pizza only
Ice cream only
Neither pizza nor ice cream
Both pizza and ice cream
Cannot be assumed from the data show
Among persons eating ice cream, over 70% developed diarrhea regardless of their
pizza consumption (39/52 and 11/15). Among both groups of persons who did not
eat ice cream, each attack rate was equal to or less than 35% (14/40 and 9/30).
Which of the following reasons can explain why a person who did not
consume the infective food item got sick?
They were directly exposed to persons who did eat the infective food item
Diarrhea is a general symptom consistent with a number of illnesses
There may have been an inaccurate recall of which foods were eaten
All of the above
None of the above
Which of the following is a condition which may occur during the incubation
period?
Transmission of infection
The incubation period is defined as the interval from receipt of infection to the
time of onset of clinical illness. Accordingly, individuals may transmit infectious
agents during the incubation period as they show no signs of disease that would
enable the isolation of sick individuals by quarantine.
Chicken pox is a highly communicable disease. It may be transmitted by
direct contact with a person infected with the varicella-zoster virus (VZV).
The typical incubation time is between 10 to 20 days. A boy started school 2
weeks after showing symptoms of chicken pox including mild fever, skin rash,
and fluid-filled blisters. One month after the boy returned to school, none of
his classmates had been infected by VZV. The main reason was:
Contact was after infectious period
Subclinical infections were not yet detected
Disease was endemic in the class
The disease is spread by contact with an infected individual who can transmit the
agent (VZV) to immunologically naive persons during the incubation period and
for several days after onset of clinical illness. Since the boy started school 14 days
,after showing signs consistent with chicken pox, it is most likely that he was no
longer infectious.
The ability of a single person to remain free of clinical illness following
exposure to an infectious agent is known as:
Hygiene
Vaccination
Herd immunity
Immunity
Latency
Immunity is the capacity of a single individual to avoid disease susceptibility when
exposed to an infectious agent. Herd immunity is a population characteristic. For
certain diseases, individual immunity can be acquired by vaccination, but this is
not true for all infectious diseases.
Which of the following is characteristic of a single-exposure, common-vehicle
outbreak?
Long latency period before many illnesses develop
There is an exponential increase in secondary cases following initial
exposures
Cases include only those who have been exposed to sick persons
The epidemic curve has a normal distribution when plotted against the
logarithm of time
Wide range in incubation times for sick individuals
Single-exposure, common-vehicle outbreaks involve a sudden, rapid increase in
cases of disease that are limited to persons who share a common exposure.
,Additionally, few secondary cases develop among persons exposed to primary
cases. A histogram of the outbreak can plot the number of cases by time of disease
onset. In single-exposure, common-vehicle outbreaks, a log transformation of the
time of disease onset will often take on the characteristic shape of a normal
distribution (i.e., a bell curve) with the median incubation time found at the peak of
the curve.
What is the diarrhea attack rate in persons who ate both ice cream and pizza?
39/52
21/70
39/67
51/67
none of the above
The attack rate in this example is defined as the number of persons who develop
diarrhea divided by the total number of people at risk. In this example, the at-risk
group is those who have eaten both ice cream and pizza. Of these 52 persons, 39
developed diarrhea.
What is the overall attack rate in persons who did not eat ice cream?
30%
, 33%
35%
44%
58%
(14+9)/(40+30)= 33%
The attack rate is the number of persons with diarrhea (14 + 9) divided by the total
number of persons who did not eat ice cream (40 + 30).
Which of the food items (or combination of items) is most likely to be the
infective item(s)?
Pizza only
Ice cream only
Neither pizza nor ice cream
Both pizza and ice cream
Cannot be assumed from the data show
Among persons eating ice cream, over 70% developed diarrhea regardless of their
pizza consumption (39/52 and 11/15). Among both groups of persons who did not
eat ice cream, each attack rate was equal to or less than 35% (14/40 and 9/30).
Which of the following reasons can explain why a person who did not
consume the infective food item got sick?
They were directly exposed to persons who did eat the infective food item
Diarrhea is a general symptom consistent with a number of illnesses
There may have been an inaccurate recall of which foods were eaten
All of the above
None of the above
