Oral rabies vaccine (ORV) bait uptake by striped skunks: Preliminary results
Aerial delivery of rabies vaccine-laden bait is effective and efficient for large-scale vaccination of wildlife. Oral rabies vaccine (ORV) contained in a sachet (or blister pack) inside baits that serve as the mode of delivery currently are used for orally immunizing foxes, raccoons, and coyotes. The technique remains in the vaccine-development stage for oral immunization of skunks. Since skunks are a major vector of the rabies virus, concurrent development of a bait that is sufficiently attractive to skunks would facilitate an immediate mode of delivery once a vaccine is developed. We ran a palatability experiment with different shapes and flavors of baits to assess uptake by captive skunks. The flavors most preferred were fish and chicken. We also evaluated the fate of the sachet (punctured or not) inside baits, which would assist in assessing the delivery of a vaccine dose. On average, cylindrical-shaped baits had a higher percentage of punctured sachets than did rectangular-shaped baits, and baits with their matrix directly coated onto the sachet had a higher percentage of punctured sachets than did those baits in which the sachet was “held.” We also used sulfadimethoxine, a short-term quantifiable biomarker, as a mock vaccine inside sachets in an attempt to quantify the amount of liquid ingested by skunks after consuming baits of different shape and size. While this information could have been useful for assessing the amount of vaccine delivered via sachet puncture, it could not be determined due to an aversive tasting biomarker. For effective ORV bait uptake by skunks, modifications to current baits should include a smaller size and a meat flavor matrix that is directly coated onto the sachet.