Q: Which equation correctly represents the calculation of disease incidence?

Incidence = $$\frac{\text{Number of new cases}}{\text{Population at risk}}$$

Question 1

Which of the following best describes mutualism in a symbiotic relationship?

Accepted Answer

Both organisms benefit from the relationship.

Question 2

Resident microbiota are typically found throughout a person's life. Which of the following is NOT a reason why transient microbiota cannot persist in the body?

Accepted Answer

They are protected by the host's immune system.

Question 3

Which of the following is an example of an opportunistic pathogen?

Accepted Answer

Normal microbiota causing disease when introduced to an unusual site in the body.

Question 4

Why is absolute commensalism difficult to prove?

Accepted Answer

It is hard to demonstrate that one organism is completely unaffected by the other.

Question 5

Which of the following is a nonliving reservoir for infectious diseases?

Accepted Answer

Soil contaminated by feces or urine.

Question 6

A pregnant woman contracts syphilis. Which portal of entry allows the pathogen to infect the fetus?

Accepted Answer

Placenta

Question 7

Which of the following statements about adhesion is correct?

Accepted Answer

Adhesion is required for microorganisms to establish colonies within the host.

Question 8

Which equation correctly represents the calculation of disease incidence?

Accepted Answer

Incidence = $$\frac{	ext{Number of new cases}}{	ext{Population at risk}}$$

Question 9

Which of the following is a characteristic of exotoxins?

Accepted Answer

They are proteins secreted by living bacterial cells.

Question 10

A patient develops a secondary infection after antibiotic treatment for a primary infection. What is the most likely cause?

Accepted Answer

Opportunistic pathogens thrive after resident microbiota are inhibited.

Question 11

Which stage of infectious disease is characterized by the most severe signs and symptoms?

Accepted Answer

Illness

Question 12

Which of the following is a biological vector for malaria?

Accepted Answer

Anopheles mosquito

Question 13

Which term describes a disease that is easily spread from one host to another?

Accepted Answer

Contagious disease

Question 14

Why is mutated Streptococcus pneumoniae, which cannot make a capsule, unable to cause pneumonia?

Accepted Answer

The capsule is an antiphagocytic factor that prevents phagocytosis by host cells.

Question 15

Which of the following is the most effective way to reduce healthcare-associated infections?

Accepted Answer

Handwashing

Question 16

A disease is classified as acute if:

Accepted Answer

Symptoms develop rapidly and the disease runs its course quickly.

Question 17

Which of the following is NOT a mode of vehicle transmission?

Accepted Answer

Direct contact with an infected person

Question 18

Which equation correctly represents the calculation of disease prevalence?

Accepted Answer

Prevalence = $$\frac{	ext{Total cases}}{	ext{Population at risk}}$$

Question 19

Which of the following is a reason why an acute disease with a high rate of mortality is unlikely to be associated with a pandemic?

Accepted Answer

The disease kills hosts quickly, limiting its spread.

Question 20

Which of the following is a plausible explanation for why not all arthropod vectors are reservoirs?

Accepted Answer

Some vectors only transmit pathogens without maintaining them as a source of infection.

Infection, Infectious Diseases, and Epidemiology – Study Notes

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