Disaggregate your model to deal with the case of a virus that affects different age
cohort in the population differently. An example for such a disease is chicken pox.
Chicken pox is a highly infectious childhood disease. It is caused by the varicella
zoster virus. This virus can be spread either through direct contact with infected
individuals or through the air. After exposure to the virus, the incubation period
before an individual becomes contagious is approximately seven days. Individuals
are contagious for about seven days during which symptoms including fever and
blisters appear, and then remain sick for an additional fourteen days. Once an
individual recovers he or she develops a natural immunity and is unlikely to get
the disease again.
Later in life, the varicella zoster virus manifests itself in the form of shingles in
about 15 % of the population that contracted chicken pox. Shingles has symptoms
that are similar to chicken pox but strikes mostly individuals over the age of fifty
that are fatigued or under stress. It takes approximately ten days to recover from
shingles and during this time susceptible individuals can contract chicken pox from
those suffering from shingles.
Recently, a vaccine has been approved to immunize people against chicken pox.
The target population for immunization are children, as they comprise the highest
infectious class. What are the effects of chicken pox on a given population and how
do those effects change as immunization takes place? What are the effects of
immunization during childhood on the occurrence of shingles? How does an
immunization policy effect the average age at which a person contracts the disease?
Set up a model to provide answers to these questions. To achieve some realism with
your model, consult the literature for parameter values, such as Edelstein-Keshet
[2], Finger et al. [3], May [4], and Hethcote [5].
Fig. 21.7
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cohort in the population differently. An example for such a disease is chicken pox.
Chicken pox is a highly infectious childhood disease. It is caused by the varicella
zoster virus. This virus can be spread either through direct contact with infected
individuals or through the air. After exposure to the virus, the incubation period
before an individual becomes contagious is approximately seven days. Individuals
are contagious for about seven days during which symptoms including fever and
blisters appear, and then remain sick for an additional fourteen days. Once an
individual recovers he or she develops a natural immunity and is unlikely to get
the disease again.
Later in life, the varicella zoster virus manifests itself in the form of shingles in
about 15 % of the population that contracted chicken pox. Shingles has symptoms
that are similar to chicken pox but strikes mostly individuals over the age of fifty
that are fatigued or under stress. It takes approximately ten days to recover from
shingles and during this time susceptible individuals can contract chicken pox from
those suffering from shingles.
Recently, a vaccine has been approved to immunize people against chicken pox.
The target population for immunization are children, as they comprise the highest
infectious class. What are the effects of chicken pox on a given population and how
do those effects change as immunization takes place? What are the effects of
immunization during childhood on the occurrence of shingles? How does an
immunization policy effect the average age at which a person contracts the disease?
Set up a model to provide answers to these questions. To achieve some realism with
your model, consult the literature for parameter values, such as Edelstein-Keshet
[2], Finger et al. [3], May [4], and Hethcote [5].
Fig. 21.7
174
21 Infectious Diseases