Assessment of fox control in areas of wildlife rabies

This paper describes a technique for the analysis of the interaction between rabies control measures and the annual turnover of a fox population. The basic conditions are deduced from data on the turnover of a steady fox population, which have been found to be representative for large parts of central Europe. These conditions, together with field data on the critical density for rabies transmission and the recovery of reduced fox populations, provide a model for the prediction and evaluation of various measures of rabies control. The method is simplified by the introduction of a semigraphical procedure using the relative density of a reduced fox population, defined as the ratio of the actual population density to that of a non-reduced population.Simulation of epidemics and control measures over consecutive population cycles shows the limited effect of population control in a rabies-free area and demonstrates the questionable impact of measures that reduce a regular fox population by less than 40%, even when such reduction is effected annually.The method is easy to apply in the field and helps in assessing a number of disease and service indicators, as well as ecological factors in the planning and evaluation of comprehensive rabies control programmes.