Lecture 3

Question 1

Single host transmission mechanisms

Answer 1

1. Droplets
2. Direct contact (Sexually transmitted, bites, perinatal)
3. Environmental contamination

Question 2

Abundance population growth

Answer 2

Growth rate is directly proportional to individuals in population

Question 3

What is a problem with this model abundance population growth?

Answer 3

It predicts limitless growth to massive population sizes
-resources eventually run out

Question 4

What is beta in SIR model

Answer 4

Transmission rate per unit

Question 5

What is k in the SIR model

Answer 5

Number of contacts per unit time

Question 6

What is pi

Answer 6

Transmission probability per contact

Question 7

What is N in SIR

Answer 7

Population size

Question 8

In the S’ model why is the transmission rate negative

Answer 8

Loss of susceptibles becomes/moves to infected so (-)

Question 9

How to find the amount of time you remain sick for

Answer 9

1/gamma

Question 10

What is gamma*I in I’ model

Answer 10

Transmission rate of infectious to resistant (get better)

Question 11

What is gamma*I in R’ model

Answer 11

Probability of becoming resistant

Question 12

What does the S’ model

Answer 12

Transmission of S to I

Question 13

What is does the I’ model

Answer 13

Transmission of I to R

Question 14

What does the R’ model

Answer 14

Probability of becoming R

Question 15

What is R0

Answer 15

How many people 1 infected individual will infect

Question 16

How to find R0 (Basic reproduction number)

Answer 16

R0 = (BN) / (1y)

Question 17

How do we know if an epidemic will continue or not continue

Answer 17

R0 > 1 = epidemic continues
R0 < 1 = epidemic dies out

Question 18

How to find herd immunity threshold

Answer 18

1 - 1/R0

Question 19

Total infected is not the same as herd immunity threshold. Why?

Answer 19

Some individuals are still infectious once the herd immunity threshold is hit

Question 20

True or false: As population increases R0 decreases

Answer 20

False
-As population increases R0 increases

Question 21

True or false: As population decreases R0 decreases as well

Answer 21

True

Question 22

Why might culling be used when there is a disease outbreak in animals

Answer 22

R0 depends on population density, so if we lower the animal population the