1.)You are studying a population of wild coyotes and notice that every three years there is an epidemic of a bacterial disease. Which of the following best explains this periodic cycling of the disease?

New coyotes are continuously born into the population.

Coyotes are dying from other causes over time.

During an outbreak, the proportion of coyotes who are sick with the disease slowly falls as they recover.

Coyotes from other populations, who have already caught and recovered from the disease, immigrate into the study population.

2.) Two directly transmitted viral diseases have the same critical immunization threshold (pc) even though their effects on the host are different. Which of the following differences between the two diseases could lead to the same critical immunization threshold?

Answers:

One disease has a higher transmission rate and a longer recovery period than the other.

One disease has a lower transmission rate and a longer recovery period than the other.

One disease has a lower transmission rate and a shorter recovery period than the other.

For one disease, the recovery period is long; for the other, no one recovers.

3.)  You are devising a vaccination program for a strain of influenza with an estimated R0 of 2.5. What proportion of a susceptible population do you need to vaccinate to impart herd immunity and prevent an epidemic?

4.)Examine the two graphs on the right, paying close attention to their x and y axis labels. Which statement below is supported by these data?

Both graphs reflect density-dependent disease transmission.

Both graphs reflect frequency-dependent disease transmission.

Disease Q (top) displays density-dependent transmission, while Disease Z (bottom) displays frequency-dependent transmission.

Disease Q (top) displays frequency-dependent transmission, while Disease Z (bottom) displays density-dependent transmission.