Question 1

Refer to the epidemic curves shown in the image. Which type of epidemic is represented by the curve with a sharp peak (dotted line with squares), and what is the most likely explanation for this pattern?

Accepted Answer

Common source epidemic; caused by exposure to a single contaminated source.

Question 2

Based on the epidemic curves, which type of epidemic is characterized by a slower rise and fall in the number of cases (solid line with circles), and what does this indicate about the mode of transmission?

Accepted Answer

Host-to-host epidemic; indicates ongoing person-to-person transmission.

Question 3

If a new infectious disease shows an epidemic curve similar to the solid line in the image, which public health intervention would be most effective in controlling the outbreak?

Accepted Answer

Isolating infected individuals to prevent further person-to-person spread.

Question 4

Which mathematical model best describes the rapid rise and fall of cases in a common source epidemic as shown in the image?

Accepted Answer

$$I(t) = \frac{a}{(t-t_0$)^2 + b$$}$

Question 5

Suppose a contaminated water supply caused the epidemic represented by the dotted line in the image. What is the most important first step in stopping the outbreak?

Accepted Answer

Identifying and removing the contaminated water source.

Question 6

Which of the following best explains why the host-to-host epidemic curve (solid line) is broader and less peaked than the common source epidemic curve (dotted line)?

Accepted Answer

Host-to-host transmission requires repeated contacts over time.

Question 7

If the basic reproduction number $$R_0$$ for a host-to-host epidemic is greater than 1, what does this imply about the epidemic curve?

Accepted Answer

The number of cases will increase, leading to an epidemic.

Question 8

Which of the following scenarios would most likely produce an epidemic curve similar to the common source pattern shown in the image?

Accepted Answer

A contaminated batch of food served at a single event.

Question 9

Given the epidemic curves, which type of epidemic would you expect to see if a pathogen is introduced into a population with no prior immunity and spreads only through direct contact?

Accepted Answer

A gradual increase and decrease in cases over time.

Question 10

If a public health official observes an epidemic curve with a rapid onset and decline, what should they suspect about the source of infection?

Accepted Answer

It is likely a common source outbreak.

Microbiology Lab Practical Study Guide: Epidemics

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