Improving Rabies Vaccine Baits

Abstract

The U.S. Department of Agriculture distributes more than 10 million tetracycline-containing rabies vaccine baits to control the spread of wildlife-vectored rabies to humans, pets, and livestock. To estimate the percent of target species consuming the baits, raccoons were collected in baited areas and teeth were analyzed for the presence of the tetracycline biomarker. Several incidents of low biomarker detection rates prompted an investigation of the stability of the biomarker in the baits. These studies indicated that a portion of the tetracycline was converted to epitetracycline. Additionally, significant quantities of both compounds were trapped in the polymer which is homogeneously distributed throughout the bait. This situation is likely responsible for low biomarker detection rates. To alleviate this problem, we developed an alternative bait matrix which permits increased stability and bioavailability of the tetracycline biomarker. This new bait matrix increased the availability of the tetracycline marker from 25.2 to 87.3% and decreased epitetracycline formation from 12.4 to 3.6%.