Meeting Abstract
Oral rabies vaccination (ORV) programs in North American have historically been effective in controlling the spread of rabies in raccoon, fox, and coyote populations. However, despite being a major rabies vector, the striped skunk is unresponsive to the vaccination programs utilizing oral rabies baits. Because they are responsive to the vaccine itself, solutions such as changing bait size or varying attractant scent have been proposed, but none have made a substantial effect when implemented. In this study, we explore biomechanical and physiological differences relating to biting, bait handling, oral processing and swallowing between skunks and raccoons that may contribute to differences in oral immunization success. The results of biomechanical models informed by jaw muscle and skeletal structure revealed that fiber architecture in skunks enables the production of high bite forces at large gapes. Bite force studies confirmed these results, with skunks biting just as hard as the raccoons at the same absolute gapes that match the size of the rabies baits utilized in ORV programs. Lastly, fluoroscopy studies revealed that skunk swallow speed may contribute to insufficient coverage of the lymphoid tissue for antibody production. This study represents the first time, to our knowledge, that comparative biomechanics have been used to address differences in vaccination program outcomes within and between species. With renewed interest in oral immunization as a safe, easily administered alternative to traditional vaccines, this study sets a precedent that will be useful to vaccine-bait developers.
