Database Reference
In-Depth Information
drive observed patterns in this disease system, some parameters were varied within
the ranges provided by
6
to help clarify interesting patterns that emerge from these
models.
The RECOVERY RATE, for example, was set to 0.05 individuals recovering per
day to generalize the model to the broader avian community. Unlike the American
crow, in which the disease has a high fatality rate
7
, other avian species demonstrate
variable survival
8
. The BITE RATE was set to the high end of the estimated range
for American crows,
6
which is still likely an underestimation of the total bite rate on
a complete avian community. Finally, unlike in the original model, a seasonal “on-
off” switch (using an if-then statement) was added to the BITE RATE, MOSQUITO
DEATH RATE, and OVIPOSITION RATE to qualitatively mimic the basic seasonal
dynamics during which temperature alters annual mosquito activity. Figures 12.5
and 12.6 demonstrate the structure of this base model in STELLA for the host and
vector, respectively.
WNV has been shown to persist in overwintering mosquitoes, and many re-
searchers believe that this contributes to the persistence of the virus through the
Fig. 12.5
7
Yaremych, S., R. Warner, P. Mankin, J. Brawn, A. Raim, and R. Novak. 2004. West Nile Virus
and High Death Rate in American Crows. Emerging Infectious Diseases. 10(4): 709-711.
8
Komar, N., Langevin, S. Hinten, S., Nemeth, N. Edwards, E., and D. Hettler et al. 2003. Ex-
perimental Infection of North American Birds with the New York 1999 strain of West Nile Virus.
Emerging Infectious Diseases. 9: 311-22.
