Database Reference
In-Depth Information
1: NUMBER SUSCEPTIB…
2: NUMBER INFECTED
3: NUMBER RECOVERED
4: TOTAL POPULATION
1:
182
2:
4
3:
4:
4
4
4
1:
3
2:
91
3:
3
4:
1
3
3
1
1
1
2
1:
2:
2
2
3:
2
4:
0
0.00
50.00
100.00
150.00
200.00
Days
Untitled
Fig. 12.4
1. What other factor(s) might also contribute to persistence of a disease in a pop-
ulation? (Hint: How might you model an evolving pathogen that can rapidly re-
infect and cause disease in previously exposed individuals?)
2. How would you model migration of new susceptible individuals from a neighbor-
ing population and what impact would migration have on the outbreak dynamics?
SIMPLE POPULATION-DYNAMIC SIR MODEL
NUMBER INFECTED(t)
=
NUMBER INFECTED(t
−
dt)
+
(INFECTING
−
RECOVERING
I DYING) * dt
INIT NUMBER INFECTED
−
=
3
INFLOWS:
INFECTING
=
NUMBER SUSCEPTIBLE * INFECTION RATE
OUTFLOWS:
RECOVERING
=
NUMBER INFECTED * RECOVERY RATE
I DYING
=
DEATH RATE*NUMBER INFECTED
+
DZ MORTALITY RATE*NUMBER INFECTED
NUMBER RECOVERED(t)
=
NUMBER RECOVERED(t
−
dt)
+
(RECOVERING
−
LOSING IMMUNITY
−
R DYING) * dt
INIT NUMBER RECOVERED
=
0
INFLOWS:
RECOVERING
=
NUMBER INFECTED * RECOVERY RATE
OUTFLOWS:
LOSING IMMUNITY
=
NUMBER RECOVERED*IMMUNITY LOSS RATE
R DYING
NUMBER RECOVERED * DEATH RATE
NUMBER SUSCEPTIBLE(t)
=
=
NUMBER SUSCEPTIBLE(t
−
dt)
+
