$$ \text{Incidence Rate} = \frac{\text{Number of new cases during a specific period}}{\text{Number of individuals at risk in the population}} $$

Question 1

Which of the following best describes the relationship between normal microbiota and the host in mutualism?

Accepted Answer

Both organisms benefit from the relationship.

Question 2

A patient develops a secondary infection after being treated for influenza. Which of the following best explains this phenomenon?

Accepted Answer

An opportunistic pathogen caused an infection after the primary illness weakened the host.

Question 3

Which of the following is NOT a step in Koch’s postulates?

Accepted Answer

The microorganism must cause a different disease when introduced into a healthy host.

Question 4

A disease that is constantly present in a population is best described as:

Accepted Answer

Endemic

Question 5

Which of the following is an example of vehicle transmission?

Accepted Answer

Drinking contaminated water and contracting cholera

Question 6

Which of the following equations correctly represents the calculation for incidence rate?

Accepted Answer

$$ 	ext{Incidence Rate} = \frac{	ext{Number of new cases during a specific period}}{	ext{Number of individuals at risk in the population}} $$

Question 7

Which of the following best describes a nosocomial infection?

Accepted Answer

An infection acquired while receiving treatment in a healthcare facility

Question 8

A disease that spreads rapidly to many people in a given area in a short time is classified as:

Accepted Answer

Epidemic

Question 9

Which of the following is a predisposing factor that can increase susceptibility to disease?

Accepted Answer

Inherited traits such as the sickle cell gene

Question 10

Which of the following best describes herd immunity?

Accepted Answer

Immunity in most of a population that limits the spread of disease

Question 11

A patient is diagnosed with bacteremia. What does this indicate?

Accepted Answer

Bacteria are present in the blood.

Question 12

Which of the following is a key difference between signs and symptoms of disease?

Accepted Answer

Signs can be measured or observed, while symptoms are felt by the patient.

Question 13

Which of the following is an example of biological vector transmission?

Accepted Answer

A mosquito transmits malaria after the parasite reproduces inside it.

Question 14

Which of the following is a reason why Koch’s postulates cannot always be applied to identify the cause of a disease?

Accepted Answer

Some pathogens cannot be cultured in the laboratory.

Question 15

Which of the following best describes an acute disease?

Accepted Answer

Symptoms develop rapidly but the disease lasts only a short time.

Question 16

Which of the following is the correct formula for calculating relative risk?

Accepted Answer

$$ 	ext{Relative Risk} = \frac{	ext{Incidence rate among exposed}}{	ext{Incidence rate among unexposed}} $$

Question 17

Which of the following is an example of a zoonosis?

Accepted Answer

Rabies transmitted from a dog to a human

Question 18

Which of the following is a major contributing factor to the emergence of new infectious diseases?

Accepted Answer

Genetic recombination in pathogens

Question 19

Which of the following best describes the prodromal period of a disease?

Accepted Answer

A short period after incubation with early, mild symptoms

Question 20

Which of the following is the best example of microbial antagonism?

Accepted Answer

Normal microbiota competing with pathogens for nutrients

Principles of Disease and Epidemiology: Study Guide

Study Guide - Practice Questions