Question 1

Pathogenic E.coli strain O157:H7 evolved from a non-pathogenic strain as a result of this genetic change.

Accepted Answer

A)   A mutation in a virulence gene.
B)   A mutation that resulted in antibiotic resistance.
C)   The acquisition of virulence genes from Shigella.
D)   The use of antibiotic supplements in animal feeds.
E)   A mutation that resulted in increased capsule production.F) A) and E)
G) B) and E)

Question 2

Vertical transmission of a pathogenic agent occurs from mother to child.

Accepted Answer

A) True 
 B)False

Question 3

How does vertical transmission of a pathogen occur?

Accepted Answer

A)   By an aerosol route.
B)   As a result of an insect bite.
C)   From mother to offspring.
D)   By a sexual route.
E)   By ingesting contaminated water.F) C) and D)
G) A) and E)

Question 4

The emergence of Lyme disease was most likely a result of:

Accepted Answer

A)   an increase in virulence of the spirochete.
B)   a change in human activity that allowed for an increased risk for contact with the pathogen.
C)   a mutation in an existing spirochete that allowed for increase spread between humans.
D)   a rare zoonotic transfer of the spirochete strain to humans.
E)   an increase in the tick population.F) A) and D)
G) A) and E)

Question 5

Which of these is an example of a common-source epidemic?

Accepted Answer

A)   A single case of H1N1 influenza is reported in a small town.
B)   A prison has a higher rate of tuberculosis than is typical.
C)   A number of children show up at school with measles.
D)   Several cases of food poisoning from a wedding.
E)   A local hospital sees cases of several different "staph" infections in a weekF) B) and D)
G) B) and C)

Question 6

When the incidence of a disease occurs at a level higher than expected,it is called a(n)______________.

Accepted Answer

The answer of When the incidence of a disease occurs...

Question 7

This is an example of a pathogen that has become more of a threat because it is increasingly harder to control with antimicrobials.

Accepted Answer

A)   MRSA
B)   E.coli O157:H7
C)   HIV/AIDS
D)   Ebola virus
E)   Measles virusF) B) and C)
G) A) and E)

Question 8

How is the protozoan Plasmodium falciparum transmitted from host to host?

Accepted Answer

A)   an aerosol route
B)   a fomite
C)   contaminated food or water
D)   a vector-borne route
E)   sexual contactF) A) and B)
G) A) and E) D

Question 9

Which of these outcomes is the focus of molecular Koch's postulates?

Accepted Answer

A)   The isolation of the pathogen.
B)   The identification of the pathogen.
C)   The determination of the LD₅₀.
D)   The determination of the ID₅₀.
E)   The identification of virulence factor genes.F) D) and E)
G) C) and E)

Question 10

The Herpes simplex I virus is able to avoid detection by the host immune system through this mechanism.

Accepted Answer

A)   Antigenic variation.
B)   The production of proteases that destroy antibodies.
C)   The establishment of latency in sensory neurons.
D)   The production of cytotoxins that kill macrophages.
E)   The inhibition of B-cells.F) B) and D)
G) A) and C)

Question 11

Pathogens that have the ability to change their surface antigens are better able to do which of the following?

Accepted Answer

A)   acquire nutrients
B)   evade host defenses
C)   attach to host cells
D)   exit the host successfully
E)   enter host cellsF) C) and E)
G) All of the above

Question 12

Endotoxins are toxins that are made in the cell and excreted to the external environment.

Accepted Answer

A) True 
 B)False

Question 13

The ability of Staphylococcus aureus to become antibiotic resistant is referred to as antigenic variation.

Accepted Answer

A) True 
 B)False

Question 14

When the virulence of a pathogen is decreased to such a degree that it no longer can cause disease it is termed a(n)_______________ strain.

Accepted Answer

avirulent or attenuated

Question 15

What is the morbidity rate of a disease?

Accepted Answer

A)   The number of cases of the disease within a specified number of the population.
B)   The number of deaths due to an infectious agent.
C)   The ratio of the number of deaths to the number of individuals with the disease.
D)   The total number of cases of a disease.
E)   The number of deaths within a population.F) A) and E)
G) C) and D)

Question 16

The emergence of HIV/AIDS disease was most likely a result of:

Accepted Answer

A)   an increase in virulence of an existing human retrovirus.
B)   a change in human behavior that allowed the virus to spread.
C)   a mutation in an existing retrovirus that allowed for increased spread between humans.
D)   a rare zoonotic transfer of a retrovirus strain to humans.
E)   an increase in homosexual activity among humans.F) C) and D)
G) All of the above

Question 17

What does a high case-to-infection ratio (CI) indicate?

Accepted Answer

A)   That the disease is usually fatal.
B)   That most people infected by the pathogen will develop the disease.
C)   That most people infected by the pathogen will not develop the disease.
D)   That the disease is usually very mild.
E)   That the pathogen is transmitted by an aerosol route.F) B) and C)
G) A) and E)

Question 18

The replication of a microbial pathogen on or within a host is called a(n)__________________.

Accepted Answer

The answer of The replication of a microbial pathogen on...

Question 19

Term for a clustering of virulence genes on the chromosome of a pathogenic microbe.

Accepted Answer

A)   transposon
B)   pathogenicity island
C)   operon
D)   promoter
E)   enhancer regionF) A) and B)
G) None of the above

Question 20

A pathogen that causes disease in a healthy host when displaced from its usual location in the body could be termed opportunistic.

Accepted Answer

A) True 
 B)False  True

Exam 18: Introduction to Infectious Diseases

Pathogenic E.coli strain O157:H7 evolved from a non-pathogenic strain as a result of this genetic change.

Correct AnswerverifiedShow Answer

Vertical transmission of a pathogenic agent occurs from mother to child.

Correct AnswerverifiedShow Answer

How does vertical transmission of a pathogen occur?

Correct AnswerverifiedShow Answer

The emergence of Lyme disease was most likely a result of:

Correct AnswerverifiedShow Answer

Which of these is an example of a common-source epidemic?

Correct AnswerverifiedShow Answer

When the incidence of a disease occurs at a level higher than expected,it is called a(n)______________.

Correct AnswerverifiedShow Answer

This is an example of a pathogen that has become more of a threat because it is increasingly harder to control with antimicrobials.

Correct AnswerverifiedShow Answer

How is the protozoan Plasmodium falciparum transmitted from host to host?

Correct AnswerverifiedD

Which of these outcomes is the focus of molecular Koch's postulates?

Correct AnswerverifiedShow Answer

The Herpes simplex I virus is able to avoid detection by the host immune system through this mechanism.

Correct AnswerverifiedShow Answer

Pathogens that have the ability to change their surface antigens are better able to do which of the following?

Correct AnswerverifiedShow Answer

Endotoxins are toxins that are made in the cell and excreted to the external environment.

Correct AnswerverifiedShow Answer

The ability of Staphylococcus aureus to become antibiotic resistant is referred to as antigenic variation.

Correct AnswerverifiedShow Answer

When the virulence of a pathogen is decreased to such a degree that it no longer can cause disease it is termed a(n)_______________ strain.

Correct Answerverifiedavirulent or attenuated

What is the morbidity rate of a disease?

Correct AnswerverifiedShow Answer

The emergence of HIV/AIDS disease was most likely a result of:

Correct AnswerverifiedShow Answer

What does a high case-to-infection ratio (CI) indicate?

Correct AnswerverifiedShow Answer

The replication of a microbial pathogen on or within a host is called a(n)__________________.

Correct AnswerverifiedShow Answer

Term for a clustering of virulence genes on the chromosome of a pathogenic microbe.

Correct AnswerverifiedShow Answer

A pathogen that causes disease in a healthy host when displaced from its usual location in the body could be termed opportunistic.

Correct AnswerverifiedTrue

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avirulent or attenuated

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