Comparison of the efficacy of the antirabies vaccines used for foxes in France.

Three manufactured antirabies vaccine baits made with the SAD B19, SAG 1 or VRG viruses have been used in a large scale programme in France since 1986. All three baits were found to be effective in achieving a significant decrease in the incidence of rabies, or even its local eradication. The VRG vaccine bait was found to be the most efficient, and resulted in rabies elimination in a non-alpine region after only two campaigns. The fact that the VRG-vaccinated bait was significantly better than the others was probably due to the better conservation of this vaccine and the bait casing in the environment even under summer conditions. The stability of the SAG 1 vaccine bait was improved in 1992, and it has since been giving good results. The choice of the pattern of the vaccination periods appeared to be a determining factor: distribution during spring, then autumn, then spring was found to be more efficient than a distribution during autumn, then spring, then autumn. A distribution of VRG bait during the summer of 1992 was far less efficient due to the lower percentage of foxes that take the baits during this period, despite the proven stability of the baits in such conditions.