Post by Johnathan Kiel, DVM, PhD

When I was in veterinary school over 50 years ago, my professor in wildlife diseases decided to vaccinate endangered Bighorn Sheep against Blue Tongue Virus in west Texas to save them from extinction in Texas by aerial drop of midges (Culicoides biting midges,biting gnats) carrying an attenuated virus. It worked but he got in trouble for not getting official approval for the drops. Vaccination with modified live vaccines directly into Bighorn Sheep is now avoided because some revert to pathogenic forms, but unfortunately better vaccination strategies have not been applied to this disease in wildlife, unlike the successful one applied to rabies—a vaccinia virus oral vaccine carrying a rabies immunogenic gene (that is not pathogenic). Such aerial drops of live vaccine in edible biscuits has worked against rabies in wildlife in Texas and elsewhere.