Efficacy of a baiting system for vaccinating foxes against rabies with vaccinia-rabies recombinant virus

The efficacy of a vaccinia-rabies recombinant virus (10(8) TCID50) contained in a machine-made baiting system has been tested in 22 captive young foxes which were divided into three experimental groups of six and a control group of four foxes. Each fox in groups 1, 2 and 3 were fed one, two and three vaccine-baits, respectively, on successive days. The four unvaccinated foxes were housed separately. As shown by the incorporation of a tetracycline biomarker into their bones, all the baited foxes ingested at least one bait. Thirty days after baiting seroconversion to rabies was observed in 15 (83 per cent) of the foxes and seroconversion to vaccinia in 14 (78 per cent). Sixteen of the 18 (89 per cent) baited foxes resisted a rabies challenge 30 days after baiting. One cub was protected against rabies despite the absence of detectable anti-rabies antibody. The results demonstrate that the bait-sachet system permits a good release of the virus suspension into the mouth.