Database Reference
In-Depth Information
BIRD % RECOVERED
=
BIRD RECOV/TOTAL BIRD POPULATION
BIRD RECOVERY RATE
=
0.05
BITE RATE
150 then 0.20 else 0
IMMUNITY LOSS RATE
=
If time
>
=
0
LARVAL DEATH RATE
=
1.191
MATURATION RATE
=
0.07
MOSQ % INFECTED
=
MOSQ INFECT/TOTAL ADULT MOSQ
MOSQ DEATH RATE
=
If time
>
130 then 0.03 else 0.001
OVIPOSITION RATE
=
0.5
SEROPREVALENCE
=
(BIRD INFECT
+
BIRD RECOV)/
TOTAL BIRD POPULATION
TOTAL ADULT MOSQ
=
MOSQ EXPOS
+
MOSQ INFECT
+
MOSQ SUSCEP
TOTAL BIRD POPULATION
=
BIRD SUSC
+
BIRD RECOV
+
BIRD INFECT
TRANSITION RATE
0.1
TRANSMISSION EFFICACY B TO M
=
=
0.2
TRANSMISSION EFFICACY M TO B
=
0.9
WNV DEATH RATE
=
0.05
12.4 Avian Population Effects and Seasonal Dynamics
12.4.1 Modifications to the Base Model
To further explore the role of host and vector population dynamics in this arboviral
encephalitis system, we add model elements to incorporate host population growth
and to more explicitly model seasonal dynamics. Figures 12.8 and 12.9 demonstrate
the full model structure for the avian and mosquito components, respectively. Start-
ing with the base model as described above, we incorporate a BIRD BIRTHING
flow, which adds new individuals to the population through a simple exponen-
tial growth equation, and a background death rate with flows from each of the
bird stocks, also modeled using the simple exponential population growth model.
BIRTH RATE and DEATH RATE are conservatively estimated for a mixed bird
community as 2.5 offspring per breeding season per individual (0.025 offspring per
day with BIRD BIRTHING restricted to an estimated 3-month breeding season).
BIRD DEATH RATE is set to produce similar peak population sizes each season
for a 3-year simulation. MOSQUITO DEATH RATE is also calibrated to produce
similar peak numbers during each simulated breeding season (Figure 12.10). This
was done so that differences in disease prevalence in both the host and vector across
the simulated seasons can be attributed to differences in disease transmission and
not to major differences in peak populations. We address the role of inter-seasonal
difference in population growth rates in disease transmission in section 12.3.
