Computer Simulated Dynamics of a Rabies-Controlled Fox Population

Abstract

Computer simulation was used to examine the epizootiology of rabies in the red fox (Vulpes fulva). A hypothetical fox population was defined by age, sex, and location of its members. Reproduction and the quality and quantity of animal movements were simulated in accordance with available information. Rabies was the sole mortality source. The annual rabies cycle produced by the computer model was similar to that observed in the U. S. and Ontario, Canada. Its temporal dynamics were primarily determined by the relative number of susceptibles available at different times of year. Population mixing associated with juvenile dispersal had only a nominal influence on the rabies incidence pattern. The simulations suggest that the 3-year rabies cycle reported in Europe and Ontario, Canada could be an inherent consequence of interactions between red fox life history and the rabies transmission mechanism. This, however, is probably not true for the 4to 5-year cycles reported from areas where fox populations are primarily limited by factors other than rabies. The bite transmission mechanism appears to be well adapted to fox populations having low interindividual contact rates. In the simulations, each infective rabid fox needed to contact slightly more than 1.25 percent of the susceptible individuals in the vicinity of its travel path for rabies to become enzootic.

Pattern formation triggered by rare events: lessons from the spread of rabies

“…In contrast to other models that reproduce the wavelike pattern (Preston 1973 ;Anderson et al 1981 ;Ka$ lle! n et al 1985 ;Murray et al 1986 ;Smith & Harris 1991), we have demonstrated the generation of the pattern as an interplay of neighbourhood infection and long-distance dispersal (figure 3).…”

“…Diffusion models proved to be successful in describing the general wave-like structure of the spread of rabies on large spatial scales, whereas individual-based models, including detailed fox behaviour, allowed small-scale descriptions (Preston 1973 ;Anderson et al 1981 ;Ka$ lle! n et al 1985 ;Murray et al 1986 ;Smith & Harris 1991).…”

“…This simplification of the local dynamics allows a detailed analysis of the large-scale patterns triggered by different dispersal strategies. To demonstrate the power of this approach we model the spread of rabies, as the variety of different rabies models that have appeared in the literature (Preston 1973 ;Anderson et al 1981 ;Ka$ lle! n et al 1985 ;Murray et al 1986 ;Smith & Harris 1991 ;Barlow 1995 ;White et al 1995) over recent years allows us to fully evaluate the potential of the suggested approach.…”

Seasonality in spatial organization and dispersal of sympatric jackals (Canis mesomelas and C. adustus): implications for rabies management

“…Foxes disperse up to 50 km (Preston, 1973) and C. mesomelas have been recorded as dispersing up to 120 km (Ferguson et al, 1983). In this study eight of the 10 recorded dispersals for both species of jackal were within the study area.…”

Chance and risk of controlling rabies in large–scale and long–term immunized fox populations

“…To answer the questions posed we adjusted a simulation model (Jeltsch et al 1997), which has originally been developed to investigate the wavy and cyclic pattern formation of rabies epidemics (Preston 1973;Toma & Andral 1977;Steck & Wandeler 1980;Ka« lle¨n et al 1985;Sayers et al 1985;Murray et al 1986;Curk 1991). In the current version of the model we added a new algorithm to describe the e¡ects of large-scale and long-term vaccination of foxes.…”