Q: Calculate the incidence proportion of a disease if 18 new cases occur in a population of 120 during one month. Express your answer as a percentage and select the closest value.

$$\frac{18}{120} \times 100 = 15\%$$

Question 1

Which of the following best describes a mutualistic relationship between two organisms?

Accepted Answer

Both organisms benefit from the relationship.

Question 2

A patient is prescribed antibiotics that eliminate most of her gut bacteria. She subsequently develops a Clostridioides difficile infection. This scenario best illustrates which concept?

Accepted Answer

The microbiome protects against pathogenic infection by outcompeting harmful microbes.

Question 3

Which of the following is NOT a limitation of Koch’s original postulates?

Accepted Answer

All pathogens can be cultured on laboratory media.

Question 4

Which of the following is a sign, rather than a symptom, of infectious disease?

Accepted Answer

Fever of 39°C (102°F)

Question 5

A newborn baby acquires its initial microbiota from which of the following sources?

Accepted Answer

All of the above (birth canal, breastfeeding, contact with mother's skin, environment)

Question 6

Which of the following best describes the role of TReg cells in immune tolerance?

Accepted Answer

They suppress the activity of other T cells to prevent attacks on the microbiome and self-cells.

Question 7

Which of the following is NOT a way the human microbiome protects against infection?

Accepted Answer

Producing compounds that help us digest food.

Question 8

Which of the following is a virulence factor?

Accepted Answer

A bacterial capsule that prevents phagocytosis.

Question 9

A disease that is consistently present in a population with a regular pattern is called:

Accepted Answer

Endemic

Question 10

Calculate the incidence proportion of a disease if 18 new cases occur in a population of 120 during one month. Express your answer as a percentage and select the closest value.

Accepted Answer

$$\frac{18}{120} 	imes 100 = 15\%$$

Question 11

Which of the following best describes a noncommunicable disease?

Accepted Answer

A disease that does not spread from person to person, such as cancer.

Question 12

Which of the following is the most effective way to prevent the spread of disease via direct contact?

Accepted Answer

Hand washing

Question 13

Which of the following is an example of a mechanical vector?

Accepted Answer

A fly lands on raw chicken, then on cooked food, transferring bacteria.

Question 14

Which of the following statements about herd immunity is TRUE?

Accepted Answer

Herd immunity occurs when enough people are immune so that a disease cannot easily spread.

Question 15

Which of the following best describes the difference between vertical and horizontal disease transmission?

Accepted Answer

Vertical transmission occurs between mother and baby; horizontal transmission is any other mode of transmission.

Question 16

A hospital patient develops a urinary tract infection after catheterization. This is an example of:

Accepted Answer

A healthcare-associated (nosocomial) infection

Question 17

Which of the following is NOT a factor contributing to hospital-acquired infections (HAIs)?

Accepted Answer

Some patients are allergic to certain medications.

Question 18

Which of the following best describes the case fatality rate (CFR)?

Accepted Answer

$$	ext{CFR} = \frac{	ext{Number of deaths due to disease}}{	ext{Number of diagnosed cases}} 	imes 100$$

Question 19

Which of the following is the best example of analytical epidemiology?

Accepted Answer

Comparing the rate of lung cancer between smokers and non-smokers.

Question 20

Which of the following is true regarding emerging infectious diseases?

Accepted Answer

They may be caused by novel pathogens, mutations, or changes in human-animal interactions.

Principles of Disease and Epidemiology: Microbiology Study Guide

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