(solution) Section 1 1. A new disease has recently been discovered in a

(solution) Section 1 1. A new disease has recently been discovered in a

Question:

The questions are attached in the document below. There are 8 multiple choice questions. 

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Section 1
1. A new disease has recently been discovered in a village, and you have been brought in
to investigate. The disease appears to pass from one person to another when they
shake hands, and it can be cured with antibiotics. What can you say about this
disease?
a. It is a fungal disease that is indirectly transmitted.
b. The pathogen replicates without using host cells' replication machinery, and it is
directly transmitted.
c. It is a viral disease that is directly transmitted.
d. The pathogen replicates without using host cells' replication machinery, and it is
indirectly transmitted.
2. There are about 1,000 susceptible people living in this 1 km 2village. People who catch
the disease stay sick for about 3 days, and you estimate the chance an infected
individual will pass the disease to a susceptible they meet is 0.0002. What is R0 for this
disease?
3. Will the disease spread through the population? Why or why not?
a. No, because R0 < 1.
b. No, because people stay sick for less than 5 days, which is too short a recovery time.
c. Yes, because the population is densely packed into the village at 1,000 people / km 2.
d. Yes, because R0 < 1.
4. A higher population density, faster transmission rate, and longer infectious period
each cause a disease like influenza to spread to more people. Which of the following
statements correctly explain why?
Check all that apply:
a. At high densities, infected individuals encounter more individuals who are also
infected.
b. At high transmission rates, an infected-susceptible encounter is more likely to result
in an infection.
c. With long recovery, an infected individual is contagious longer and can infect more
susceptibles.
Section 2
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?
a. New coyotes are continuously born into the population.
b. Coyotes are dying from other causes over time.
c. During an outbreak, the proportion of coyotes who are sick with the disease
slowly falls as they recover. d. 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?
a. One disease has a higher transmission rate and a longer recovery period than the
other.
b. One disease has a lower transmission rate and a longer recovery period than the
other.
c. One disease has a lower transmission rate and a shorter recovery period than the
other.
d. 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?
a. Both graphs reflect density-dependent disease transmission.
b. Both graphs reflect frequency-dependent disease transmission.
c. Disease Q (top) displays density-dependent transmission, while Disease Z
(bottom) displays frequency-dependent transmission.
d. Disease Q (top) displays frequency-dependent transmission, while Disease Z
(bottom) displays density-dependent transmission.