Bait uptake by wild badgers and its implications for oral vaccination against tuberculosis

This is the final version. Available from Public Library of Science via the DOI in this record.Data Availability: All relevant data are within the paper and its Supporting Information files.The deployment of baits containing vaccines or toxins has been used successfully in the management of wildlife populations, including for disease control. Optimisation of deployment strategies seeks to maximise uptake by the targeted population whilst ensuring cost-effectiveness. Tuberculosis (TB) caused by infection with Mycobacterium bovis affects a broad range of mammalian hosts across the globe, including cattle, wildlife and humans. The control of TB in cattle in the UK and Republic of Ireland is hampered by persistent infection in European badgers (Meles meles). The present study aimed to determine the best strategy for maximising uptake of an oral vaccine by wild badgers, using a surrogate novel bait deployed at 40 badger social groups. Baits contained a blood-borne biomarker (Iophenoxic Acid, IPA) in order to measure consumption in badgers subsequently cage trapped at targeted setts. Evidence for the consumption of bait was found in 83% (199/240) of captured badgers. The probability that badgers had consumed at least one bait (IPA >10 μg ml-1) was significantly higher following deployment in spring than in summer. Lower uptake amongst social groups where more badgers were captured, suggested competition for baits. The probability of bait consumption was significantly higher at groups where main and outlier setts were provided with baits than at those where outliers were present but not baited. Badgers captured 10–14 days post bait feeding had significantly higher levels of bait uptake compared to those caught 24–28 days later. Uptake rates did not vary significantly in relation to badger age and whether bait was placed above ground or down setts. This study suggests that high levels of bait uptake can be achieved in wild badger populations and identifies factors influencing the potential success of different deployment strategies. The implications for the development of an oral badger vaccine are discussed.Natural Environment Research Council (NERC)Animal and Plant Health Agency (APHA

Population Estimation and Trappability of the European Badger (Meles meles): Implications for Tuberculosis Management.

peer-reviewedEstimates of population size and trappability inform vaccine efficacy modelling and are required for adaptive management during prolonged wildlife vaccination campaigns. We present an analysis of mark-recapture data from a badger vaccine (Bacille Calmette–Gue´ rin) study in Ireland. This study is the largest scale (755 km2) mark-recapture study ever undertaken with this species. The study area was divided into three approximately equal–sized zones, each with similar survey and capture effort. A mean badger population size of 671 (SD: 76) was estimated using a closed-subpopulation model (CSpM) based on data from capturing sessions of the entire area and was consistent with a separate multiplicative model. Minimum number alive estimates calculated from the same data were on average 49–51% smaller than the CSpM estimates, but these are considered severely negatively biased when trappability is low. Population densities derived from the CSpM estimates were 0.82–1.06 badgers km22, and broadly consistent with previous reports for an adjacent area. Mean trappability was estimated to be 34–35% per session across the population. By the fifth capture session, 79% of the adult badgers caught had been marked previously. Multivariable modelling suggested significant differences in badger trappability depending on zone, season and age-class. There were more putatively trap-wary badgers identified in the population than trap-happy badgers, but wariness was not related to individual’s sex, zone or season of capture. Live-trapping efficacy can vary significantly amongst sites, seasons, age, or personality, hence monitoring of trappability is recommended as part of an adaptive management regime during large–scale wildlife vaccination programs to counter biases and to improve efficiencies.Department of Agriculture, Food and the MarineTeagasc Walsh Fellowship Programm

Coding of group odor in the subcaudal gland secreation of the European badger Meles meles: chemical composition and pouch microbiota

The fermentation hypothesis predicts that odor profiles of mammals depend partly on the primary gland products excreted by the animal and partly on the composition of the bacterial flora converting these into secondary metabolites. Some mammalian odors, such as shared group odors, however, need to be consistent yet flexible (e.g., to allow for changes in social-group affiliation), and are thus predisposed for microbial mediation. Using terminal restriction fragment (TRF) length polymorphism analyses we analyzed the microbial community in subcaudal-gland secretions of European badgers (Meles meles) in relation to the chemical scent profiles as determined by gas chromatography-mass spectrometry analyses (GCMS) of 66 adults belonging to six different social groups. We found a total of 50 TRFs and 125 different chemical compounds with a subset of four TRFs best explaining the structure in the chemical matrix. Nevertheless, although semiochemical profiles were group specific, microbial profiles were not. In our approach, however, the number of operational taxonomic units exceeded the numbers of TRFs, and thus our analyses were likely limited by the afforded resolution. As it is likely that the variation in metabolic activity is found at the species-, subspecies-, or even strain-level, future high-throughput sequencing can be expected to reveal more subtle differences in the microbial communities between social groups