Database Reference
In-Depth Information
by Bogel, et al. resulted in a proposed method to evaluate populations and rabies
control in the wild.
Anderson, et al. evaluated culling, vaccination, and culling combined with vacci-
nation as control measures for vulpine rabies. Their model revealed that population
dynamics, most notably reproduction, limited the effectiveness of culling alone
49
.
Vaccination of foxes is a commonly chosen control method, but again, has had lim-
ited success, particularly in areas of high animal density and good habitat
50
.Itis
estimated that nearly 100% vaccination is required in areas of good habitat and
greater than 15 foxes per square kilometer
51
.
So vaccine programs (the current preferred method of control) are expensive and
potentially ineffective. The cost-effectiveness of an airdrop, vaccinated bait program
could be increased dramatically by more precise knowledge of the location and rate
of spread of the disease. A modeling process such as this one should be of great
help, assuming proper monitoring of the current status of the disease. The model
presented can describe a reasonable estimate of the location and rate of spread of the
disease front. The model would need to include some additional temporal variability,
such as lags in reporting the appearance of rabid foxes, in the initiation of the vaccine
drop, and between vaccine drop and discovery by the foxes, as well as the effective
life of the bait. The model could be expanded to become effective in this arena if
appropriate data were found.
FOX RABIES MODEL - BASIC MODEL COMPONENT
Adult Density Dependent Mortality
DEATHS ADULT
MIGRATORY CC THEN
DR DD ADULT ELSE DR NAT * ADULT
=
IF CELL POP
>
+
DR HUNT * ADULT
DR DD ADULT
=
IF CELL POP
>
0 THEN DDD * ADULT/CELL POP
+
(DR NAT
+
DR HUNT) * (CELL POP
−
DDD * DT) * ADULT/CELL POP
ELSE 0
Fox Population Dynamics
ADULT(t)
=
ADULT(t
−
dt)
+
(MATURING
+
A EMIGRATING
−
ADULT DYING
−
ADULT SICKENING) * dt
INIT ADULT
=
(MIGRATORY CC * .8)
INFLOWS:
MATURING
=
If (MONTH
=
1) AND (JUVENILE
>
JUVENILE DEATH)
then (JUVENILE
−
JUVENILE DEATH) else 0
A EMIGRATING
=
(ADULT IN
−
ADULT OUT)
49
Anderson et al. 1981.
50
Baer, G.M., M.K. Abelseth, and J.G. Debbie. 1971. American Journal of Epidemiology 93 487-
490. Black, J.G. and K.F. Lawson. 1973. Canadian Veterinary Journal 14 206-211.
51
Anderson et al. (1981).
