Question 1
Which of the following is a condition which may occur during the incubation period?
Onset of clinical illness
Receipt of infection
Signs and symptoms of disease
Transmission of infection
Isolation of disease carrier through quarantine
That's correct!
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.
, Question 2
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:
Herd immunity
All had been immunized prior to the school year
Contact was after infectious period
Subclinical infections were not yet detected
Disease was endemic in the class
That's correct!
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.
, Question 3
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
That's correct!
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.
, Question 4
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
That's correct!
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.
Which of the following is a condition which may occur during the incubation period?
Onset of clinical illness
Receipt of infection
Signs and symptoms of disease
Transmission of infection
Isolation of disease carrier through quarantine
That's correct!
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.
, Question 2
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:
Herd immunity
All had been immunized prior to the school year
Contact was after infectious period
Subclinical infections were not yet detected
Disease was endemic in the class
That's correct!
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.
, Question 3
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
That's correct!
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.
, Question 4
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
That's correct!
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.
