Vaccination of foxes against rabies using ingested baits

A method for immunizing foxes against rabies was evaluated. Fifteen of 36 red foxes (Vulpes fulva) fed baits impregnated with modified live virus rabies vaccine developed serum rabies neutralizing antibody. The vaccine-bait proved unstable when held at 4 C or 25 C for 96 hours prior to feeding. For safety testing the vaccine virus was administered to opossums (Didelphis virginiana), cotton rats (Sigmodon hispidus), hamsters (Mesocricetus auratus), and chickens (Gallus domesticus) in either liquid or bait form. One of ten cotton rats fed liquid vaccine died of vaccine induced rabies. No animals which ate the vaccine-baits died of vaccine induced rabies.