Database Reference
In-Depth Information
OUTFLOWS:
DIE 2
=
(1
−
SURVIVAL RATE 2) * INFECTED 2
SURVIVE 2
SURVIVAL RATE 2 * INFECTED 2
NON IMMUNE(t)
=
=
NON IMMUNE(t
−
dt)
+
(BIRTHS
−
GET SICK) * dt
INIT NON IMMUNE
=
1000000
INFLOWS:
BIRTHS
5000
OUTFLOWS:
GET SICK
=
=
CONTACT RATE * NON IMMUNE * INFECTED
+
CONTACT RATE 1 2 * NON IMMUNE * INFECTED 2
NON IMMUNE 2(t)
=
NON IMMUNE 2(t
−
dt)
+
(BIRTHS 2
−
GET SICK 2) * dt
INIT NON IMMUNE 2
=
1000
INFLOWS:
BIRTHS 2
10
OUTFLOWS:
GET SICK 2
=
=
CONTACT
RATE 2 * INFECTED 2 * NON IMMUNE 2
CONTACT RATE
.000001
CONTACT RATE 1 2
=
=
0.00015
CONTACT
RATE 2
=
.003
SURVIVAL RATE
=
.065
SURVIVAL RATE 2
=
.2
2.5 Epidemic with Vaccination
The model of this section introduces a number of features that make the model more
meaningful. Among these features are
•
the explicit inclusion of birth rates (instead of applying a fixed number of births
each period);
•
death rates that are not only influenced by the disease but that result also from
natural mortality;
•
a vaccination program that allows the population to become immune to the dis-
ease without having to first be sick;
•
mutations in the disease that result in immune people not staying immune for-
ever; and
•
ignorance of a fixed portion of the contagious population. These people are as-
sumed to be unaware that they carry the disease. Consequently, we assume that
ignorance would increase the rate at which the disease gets passed on from the
infective to the susceptible population.
The birth and natural death rates are specified graphically in this model as shown in
Figures 2.13 and 2.14.
