5.5.6 How can the bait-uptake in red foxes be determined?

Vaccine baits should contain a biomarker. TC has been used as a biomarker, but in many areas this is no longer used because of concerns that it contributes to antibiotic-resistant strains of bacteria. After a target or non-target animal has consumed bait, TC is embedded in the skeleton tissue of the animal for the rest of its life. This makes it easy to determine bait uptake by detecting TC-specific fluorescences in the tooth (canine tooth) or bone (mandibula, tibea, femur) tissue of red foxes and other bait competitors (see here).

By definition, the bait-uptake is the percentage of red foxes that have consumed bait as a result of bait distribution in a vaccination area. It is worth considering that, if the evaluation of ORV campaigns is based exclusively on bait uptake, vaccination coverage will be overestimated, as not all foxes which have consumed bait will develop a measurable immune response (capsule swallowed, separated, spillage of vaccine, not immunocompetent, induction of cellular immunity, etc.).


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Version 1 - Last updated November 2012