NR 503 FINAL EXAM QUESTION AND
ANSWERS
(COMPLETE SOLUTIONS AND RESOURCES FOR
THE COURSE EXAM)
Chapters2-4 st
1. Which of the following is a condition which may occur during the incubation peri
st st st st st st st st st st st st st
od?
a. Onset of clinical illness st st st
b. Receipt of infection st st
c. Signs & symptoms of disease st st st st
d. Transmission of infection st st
e. Isolation of disease carrier through quarantine st st st st st
Rationale: The incubation period is defined as the interval from receipt of infection
s t st st st st st st st st st st st s
to the time of onset of clinical illness. Accordingly, individuals may transmit infectio
t st st st st st st st st st st st st
us agents during the incubation period as they show no signs of disease that would ena
st st st st st st st st st st st st st st st
ble the isolation of sick individuals by quarantine.
st st st st st st st
2. Chicken pox is a highly communicable disease. It may be transmitted by direct contac
st st st st st st st st st st st st st
t with a person infected with the varicella-
st st st st st st st
zoster virus (VZV). The typical incubation time is between 10 to 20 days. A boy starte
st st st st st st st st st st st st st st st
d school 2 weeks after showing symptoms of chicken pox including mild fever, skin ras
st st st st st st st st st st st st st st
h, & fluid- st st
filled blisters. One month after the boy returned to school, none of his classmates ha
st st st st st st st st st st st st st st
d been infected by VZV. The main reason was:
st st st st st st st st
a. Herd immunity st
b. All had been immunized prior to the school year st st st st st st st st
c. Contact was after infectious period st st st st
d. Subclinical infections were not yet detected st st st st st
e. Disease was endemic in the class st st st st st
Rationale: The disease is spread by contact with an infected individual who can trans
st st st st st st st st st st st st st
mit the agent (VZV) to immunologically naive persons during the incubation per
s t s t s t s t s t s t s t s t s t st st
iod & for several days after onset of clinical illness. Since the boy started school 14 d
st st st st st st st st st st st st st s t s t s t
ays after showing signs consistent with chicken pox, it is most likely that he was n
s t s t s t s t s t s t s t s t s t st st st st st st
o longer infectious.
st st
3. Which of the following is characteristic of a single-exposure, common-
st st st st st st st st st
vehicle outbreak? st
,a. Long latency period before many illnesses develop
st st st st st st
, b. There is an exponential increase in secondary cases following initial exposures
st st st st st st st st st st
c. Cases include only those who have been exposed to sick persons st st st st st st st st st st
d. The epidemic curve has a normal distribution when plotted against the logarithm of tim
st st st st st st st st st st st st st
e
e. Wide range in incubation times for sick individuals st st st st st st st
Rationale: Single-exposure, common- st st
vehicle outbreaks involve a sudden, rapid increase in cases of disease that are limite
st st st st st s t st st st st st st st
d to persons who share a common exposure. Additionally, few secondary cases devel
st st st st st st st st st st st st
op among persons exposed to primary cases. A histogram of the outbreak can plot
st st st st st s t s t s t s t s t s t s t s t s t
the number of cases by time of disease onset. In single-exposure, common-
s t s t s t s t st st st st st st st
vehicle outbreaks, a log transformation of the time of disease onset will often take on
st st st st st st st st st st st st st st s
the characteristic shape of a normal distribution (i.e., a bell curve) with the median i
t st st st st st st st st st st st st st st
ncubation time found at the peak of the curve. st st st st st st st st
4. What is the diarrhea attack rate in persons who ate both ice cream & pizza?
st st st st st st st st st st st st st st
a. 39/52
b. 21/70
c. 39/67
d. 51/67
e. None of the above st st st
Rationale:
The attack rate in this example is defined as the number of persons who develop diar
st st st st st st st st st st st st st st st
rhea divided by the total number of people at risk. In this example, the at-
st st st st st st st st st st st st st st
risk group is those who have eaten both ice cream & pizza. Of these 52 persons, 39 de
st st st st st st st st st st st st st st st st st
veloped diarrhea. st
5. What is the overall attack rate in persons who did not eat ice cream?
st st st st st st st st st st st st st
a. 30%
b. 33%
c. 35%
d. 44%
e. 58%
Rationale:
Theattackrateisthenumberofpersonswithdiarrhea(14+9)dividedbythe total num
st st st st st st st st st st st s
t st st st st st
ber of persons who did not eat ice cream (40 + 30).
st st st st st st st st st st st
ANSWERS
(COMPLETE SOLUTIONS AND RESOURCES FOR
THE COURSE EXAM)
Chapters2-4 st
1. Which of the following is a condition which may occur during the incubation peri
st st st st st st st st st st st st st
od?
a. Onset of clinical illness st st st
b. Receipt of infection st st
c. Signs & symptoms of disease st st st st
d. Transmission of infection st st
e. Isolation of disease carrier through quarantine st st st st st
Rationale: The incubation period is defined as the interval from receipt of infection
s t st st st st st st st st st st st s
to the time of onset of clinical illness. Accordingly, individuals may transmit infectio
t st st st st st st st st st st st st
us agents during the incubation period as they show no signs of disease that would ena
st st st st st st st st st st st st st st st
ble the isolation of sick individuals by quarantine.
st st st st st st st
2. Chicken pox is a highly communicable disease. It may be transmitted by direct contac
st st st st st st st st st st st st st
t with a person infected with the varicella-
st st st st st st st
zoster virus (VZV). The typical incubation time is between 10 to 20 days. A boy starte
st st st st st st st st st st st st st st st
d school 2 weeks after showing symptoms of chicken pox including mild fever, skin ras
st st st st st st st st st st st st st st
h, & fluid- st st
filled blisters. One month after the boy returned to school, none of his classmates ha
st st st st st st st st st st st st st st
d been infected by VZV. The main reason was:
st st st st st st st st
a. Herd immunity st
b. All had been immunized prior to the school year st st st st st st st st
c. Contact was after infectious period st st st st
d. Subclinical infections were not yet detected st st st st st
e. Disease was endemic in the class st st st st st
Rationale: The disease is spread by contact with an infected individual who can trans
st st st st st st st st st st st st st
mit the agent (VZV) to immunologically naive persons during the incubation per
s t s t s t s t s t s t s t s t s t st st
iod & for several days after onset of clinical illness. Since the boy started school 14 d
st st st st st st st st st st st st st s t s t s t
ays after showing signs consistent with chicken pox, it is most likely that he was n
s t s t s t s t s t s t s t s t s t st st st st st st
o longer infectious.
st st
3. Which of the following is characteristic of a single-exposure, common-
st st st st st st st st st
vehicle outbreak? st
,a. Long latency period before many illnesses develop
st st st st st st
, b. There is an exponential increase in secondary cases following initial exposures
st st st st st st st st st st
c. Cases include only those who have been exposed to sick persons st st st st st st st st st st
d. The epidemic curve has a normal distribution when plotted against the logarithm of tim
st st st st st st st st st st st st st
e
e. Wide range in incubation times for sick individuals st st st st st st st
Rationale: Single-exposure, common- st st
vehicle outbreaks involve a sudden, rapid increase in cases of disease that are limite
st st st st st s t st st st st st st st
d to persons who share a common exposure. Additionally, few secondary cases devel
st st st st st st st st st st st st
op among persons exposed to primary cases. A histogram of the outbreak can plot
st st st st st s t s t s t s t s t s t s t s t s t
the number of cases by time of disease onset. In single-exposure, common-
s t s t s t s t st st st st st st st
vehicle outbreaks, a log transformation of the time of disease onset will often take on
st st st st st st st st st st st st st st s
the characteristic shape of a normal distribution (i.e., a bell curve) with the median i
t st st st st st st st st st st st st st st
ncubation time found at the peak of the curve. st st st st st st st st
4. What is the diarrhea attack rate in persons who ate both ice cream & pizza?
st st st st st st st st st st st st st st
a. 39/52
b. 21/70
c. 39/67
d. 51/67
e. None of the above st st st
Rationale:
The attack rate in this example is defined as the number of persons who develop diar
st st st st st st st st st st st st st st st
rhea divided by the total number of people at risk. In this example, the at-
st st st st st st st st st st st st st st
risk group is those who have eaten both ice cream & pizza. Of these 52 persons, 39 de
st st st st st st st st st st st st st st st st st
veloped diarrhea. st
5. What is the overall attack rate in persons who did not eat ice cream?
st st st st st st st st st st st st st
a. 30%
b. 33%
c. 35%
d. 44%
e. 58%
Rationale:
Theattackrateisthenumberofpersonswithdiarrhea(14+9)dividedbythe total num
st st st st st st st st st st st s
t st st st st st
ber of persons who did not eat ice cream (40 + 30).
st st st st st st st st st st st
