4.4 . Questions and Tasks
73
LOSS_OF_IMMUNITY = CONVEYOR OUTFLOW
OUTFLOWS:
INFECTION = CONTACT_RATE*SUSCEPTIBLE*INFECTED
CONTACT_RATE = . 0005
MORTALITY_RATE = . 100
4.4. Questions and Tasks
1. a) Assume that individuals infected with the virus have higher contact
rates during the first week of infection than during the subsequent
two weeks. How do the model and its results change with that
assumption?
b) Conduct a sensitivity analysis for your choice of contact rates.
2. How will the results of the model in Section 4.1 change if, alternatively,
individuals are sick for 1, 2, 3, 4, or 5 weeks before temporary immunity
sets in?
3. Change the model so that the offspring of individuals who are immune
during the time of reproduction will themselves be immune at birth, and
always stay immune to the disease. Will the disease ultimately disappear
from the population? How do your results change with changes in your
choice of parameters?
4. a) Introduce a second disease and make individuals more prone to the
second disease if they are already "stressed" by carrying the first
disease.
b) Have the infection with anyone disease increase the likelihood to be
infected with any other disease .
c) What are the impacts of different lengths of immunity for the dynamics of disease outbreaks?
d) Increase mortality rates for stressed individuals and observe the impacts on population dynamics .
5. a) Introduce environmental fluctuations such as an annual temperature
cycle, and assume that disease-induced mortality rates are higher
under extreme environmental conditions. How are the population dynamics related to environmental fluctuations?
b) Assume that the environmental fluctuations become larger through
time. How are the population dynamics related to your assumptions
about the rate of change in environmental fluctuations?
73
LOSS_OF_IMMUNITY = CONVEYOR OUTFLOW
OUTFLOWS:
INFECTION = CONTACT_RATE*SUSCEPTIBLE*INFECTED
CONTACT_RATE = . 0005
MORTALITY_RATE = . 100
4.4. Questions and Tasks
1. a) Assume that individuals infected with the virus have higher contact
rates during the first week of infection than during the subsequent
two weeks. How do the model and its results change with that
assumption?
b) Conduct a sensitivity analysis for your choice of contact rates.
2. How will the results of the model in Section 4.1 change if, alternatively,
individuals are sick for 1, 2, 3, 4, or 5 weeks before temporary immunity
sets in?
3. Change the model so that the offspring of individuals who are immune
during the time of reproduction will themselves be immune at birth, and
always stay immune to the disease. Will the disease ultimately disappear
from the population? How do your results change with changes in your
choice of parameters?
4. a) Introduce a second disease and make individuals more prone to the
second disease if they are already "stressed" by carrying the first
disease.
b) Have the infection with anyone disease increase the likelihood to be
infected with any other disease .
c) What are the impacts of different lengths of immunity for the dynamics of disease outbreaks?
d) Increase mortality rates for stressed individuals and observe the impacts on population dynamics .
5. a) Introduce environmental fluctuations such as an annual temperature
cycle, and assume that disease-induced mortality rates are higher
under extreme environmental conditions. How are the population dynamics related to environmental fluctuations?
b) Assume that the environmental fluctuations become larger through
time. How are the population dynamics related to your assumptions
about the rate of change in environmental fluctuations?