Evaluation of a bait-marking system for badgers
using SDM and RB as biomarkers
Journal
University College Dublin -
Faculty of Veterinary Medicine
Authors
Angela Southey, Paddy Sleeman* and Eamonn Gormley - Department of
Zoology, University College Cork
Abstract
The use of biomarkers play an important
role in the evaluation of bait uptake in field studies assessing oral
vaccine strategies. The technique relies on using non-toxic biomarker
substances incorporated into baits to 'mark' the animals that consume the
baits. In a previous study (Southey and others 2000), we showed that
iophenoxic acid and tetracycline were effective biomarkers for determining
the bait contact status of individual badgers. However, analysis of the
data obtained suggested that they are unsuitable for large-scale use in
vaccine delivery programmes; iophenoxic acid is expensive and blood
samples must be irradiated prior to analysis. In addition, measurement of
uptake of tetracycline only provides a retrospective record of bait uptake
as it is based on post-mortem examination of sectioned teeth samples. In
the present study we evaluated a bait-marking system for badgers
consisting of sulfadimethoxine (SDM) and rhodamine b (RB) as biomarkers.
Biomarked baits were distributed for three consecutive days in five test
territories.
A separate control territory was fed with nonbiomarked baits. The study
was carried out to assess, (1) The effect of SDM and RB on bait
acceptance, (2) The marking capacity of SDM and RB in serum and hair
samples taken from badgers captured after bait distribution. Of the
badgers (n=26) trapped in the test territories, 18 (69%) gave positive
results when tested for both biomarkers. Conversely, none of the badgers
(n=6) trapped in the control territory were biomarker positive. Analysis
of blood serum and hair samples indicated that SDM and RB persisted for up
to or at least 8 days after bait ingestion. These results indicate that
the biomarkers SDM and RB act as reliable systemic markers and have
potential application in field trials to monitor oral vaccine uptake by
badgers.
Keywords
Bait-Marking System for Badgers
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