Mycobacterium bovis (TB) in cattle is a disease with far-reaching economic effects throughout Europe but especially in Great Britain and Ireland. Wildlife reservoirs, in particular the European badger Meles meles, continue to play an important role in the transmission of the disease, although the pathways of transmission are still poorly understood. The badger is an opportunistic feeder that takes advantage of seasonally abundant foods, such as fruits and insect larvae. Badgers might therefore be expected to enter farmyards to exploit grain stores or feed concentrates. This would bring them into close proximity with livestock present in those yards, potentially increasing the likelihood of disease transmission.
This Irish study is the first to have looked at the use of a variety of farmyard types by free-ranging, GPS collared badgers from a medium-density population over a 3 years period.
We found that badgers in our study area avoided all types of farmyards but particularly those where cattle were present.
We investigated the influences of seasonality, social group members and badger gender on these preferences and found that they had no impact on this behaviour.
As our results differ from the findings of studies carried out in high-density badger populations in Great Britain it is probable that different farming practices as well as differences in badger behaviour and ecology must be taken into account when designing measures to control this disease. Increasing our knowledge of the interactions between badgers and cattle in a variety of ecological situations will assist in proactive and general control of the disease in both species.
40 badgers were studied for 3 years using GPS collars which sent data four times per night.
The actual number of badger records in farmyards was compared to the expected number.
Badgers exhibited significant avoidance of farmyards especially on cattle farms.
Seasonality, sex and social group had no impact on badger presence in farmyards
The diet of the Eurasian badger (Meles meles) in the Republic of Ireland was studied by examination of the stomach contents of 686 badgers, collected between March 2005 and September 2006. It was found that the relative importance of different food types, as indicated by their frequency of occurrence and ingested bulk in the diet, fluctuated seasonally. Tipulid larvae (Cl. Insecta, Ord. Tipulidae) dominated the diet in spring; Anura (Cl. Amphibia) and Aculeata (Ord. Hymenoptera) during the summer; and Noctuid larvae (Cl. Insecta, Ord. Noctuidae) in autumn and winter. Thus this type of foraging behaviour supports the contention that badgers are generalist foragers with seasonal food preferences. This feeding behaviour is more similar to that of badgers in Italy and Spain than to badgers in England.
In the UK and Ireland, Bacille Calmette-Guérin (BCG) vaccination of badgers has been suggested as one of a number of strategies to control or even eradicate Mycobacterium bovis infection in badgers. In this manuscript, we present the results of a badger field trial conducted in Ireland and discuss how the novel trial design and analytical
methods allowed the effects of vaccination on protection against infection and, more importantly, on transmission to be estimated. The trial area was divided into three zones North to South (A, B and C) where vaccination coverages of 0, 50 and 100%, respectively, were applied. Badgers were trapped over a 4 year period. Badgers were assigned to either placebo or vaccine treatment, with treatment allocation occurring randomly in
zone B. Blood samples were collected at each capture, and serology was performed in these samples using a chemiluminescent multiplex ELISA system (Enfer test). The analysis aimed to compare new infections occurring in non-infected non-vaccinated badgers to those in non-infected vaccinated ones, while accounting for the zone
in which the badger was trapped and the infection pressure to which this individual badger was exposed. In total, 440 records on subsequent trappings of individual non-infected badgers were available for analysis. Over the study period, 55 new infections occurred in non-vaccinated (out of 239 =23.0%) and 40 in vaccinated (out of 201 =19.9%) badgers. A Generalized Linear Model (GLM) with a cloglog link function was used for analysis. Statistical analysis showed that susceptibility to natural exposure with M. bovis was reduced in vaccinated compared to placebo treated badgers: vaccine efficacy for susceptibility, VES, was 59% (95% CI =6.5%–82%). However, a complete lack of effect from BCG vaccination on the infectivity of vaccinated badgers was observed,
i.e. vaccine efficacy for infectiousness (VEI) was 0%. Further, the basic reproduction ratio as a function of vaccination coverage (p) (i.e. R(p)) was estimated. Given that the prevalence of M. bovis infection in badgers in endemic areas in Ireland is approximately 18%, we estimated the reproduction ratio in the unvaccinated population as R(0) =1.22. Because VES was now known, the reproduction ratio for a fully vaccinated population
was estimated as R(1) =0.50. These results imply that with vaccination coverage in badgers exceeding 30%, eradication of M. bovis in badgers in Ireland is feasible, provided that the current control measures also remain in place.
Assessment of the safety of Bacillus Calmette-Guérin vaccine administered orally to badgers (Meles meles)
European badgers (Meles meles) are a wildlife reservoir for Mycobacterium bovis (M. bovis) in parts of England, Wales and Ireland, constituting a potential source of tuberculosis (TB) infection for cattle. Vaccination of badgers against TB is one of the tools available for helping reduce the prevalence of bovine TB in badgers, made possible by the licensing in 2010 of Bacillus Calmette-Guérin (BCG) vaccine for intramuscular
administration to badgers (BadgerBCG). However, practical limitations associated with administering ban injected vaccine to wild animals make an oral, bait-delivered form of the vaccine highly desirable. Evaluation of the safety of oral BCG to badgers and the environment is a mandatory step on the road to licensing an oral vaccine. This study had the following objectives: (a) to determine whether adverse effects followed the oral administration of BCG vaccine to badgers; (b) to measure the quantity and frequency of BCG excreted in the faeces of vaccinated badgers; and (c) to assess whether there was
evidence of the vaccine spreading to unvaccinated, ‘sentinel’ badgers sharing the same environment as vaccinated animals. We report here that the oral administration per badger of 6.4 109 cfu BCG, followed 14 days later by a single oral dose of 6.4 107 cfu BCG caused no adverse physical effects and the faeces of two of nine vaccinated animals (372 cfu/g and 996 cfu/g, respectively) approximately 48 h after the higher dose of BCG was administered and by one of the nine vaccinated animal (80 cfu/g)
approximately 24 h after receiving the lower dose of BCG. We found no evidence for the transmission of BCG to unvaccinated, sentinel, badgers housed with the vaccinated animals despite the occasional excretion of BCG in faeces.
Badger (Meles meles) disturbances affect oribatid mite (Acari: Oribatida) communities in European temperate forests
Burrowing mammals living in forests are one of the important disturbance factors driving changes in species community and diversity on the forest floor. In the present study we examined the impact of soil mounds createdby badgers (Meles meles) on species richness and the community structure of oribatid mites, which constitute one
of the most numerous components of soil mesofauna. We compare oribatid communities between forest soils disturbed by badgers in 1-year-old mounds and 5-year-old mounds as well as undisturbed forest soil to get an insight into the direction of temporal changes. The study plots were situated in pine forests within the Kampinos Forest (Poland). The soil parameters created by badgers and ecological groups in the oribatid fauna were analysed. The results showed that distinct oribatid communities occur in badger mounds when compared with adjacent undisturbed forest soil. It appeared that badgers have the potential to substantially affect the soil
environment in forest ecosystems and finally influenced mite abundance and community composition. Initial badger disturbance caused a significant decline in the abundance and biodiversity of oribatid mites, but within a few years the oribatid fauna was restored. Our results supported the intermediate disturbance hypothesis. Badger
activity affected the composition of ecological groups of mites, toward surface dwelling, primary decomposers and sexually reproducing species. It can be concluded that badger mounds serve as microhabitats for some soil mites and contribute to the patchiness and heterogeneity of the forest floor. Finally, oribatid community structure proved to be a good indicator of soil disturbance caused by mammal activities involving deep digging in soil and heaping mounds in temperate forests.
Effect of culling and vaccination on bovine tuberculosis infection in European badger (Meles meles) population by spatial simulation modelling
Ab s t r a c t
The control of bovine tuberculosis (bTB) in cattle herds in the Republic of Ireland (ROI) is partially hin-dered by spill-back infection from wild badgers (Meles meles). The aim of this study was to determine therelative effects of interventions (combinations of culling and/or vaccination) on bTB dynamics in an Irishbadger population. A spatial agent-based stochastic simulation model was developed to evaluate theeffect of various control strategies for bovine tuberculosis in badgers: single control strategies (culling,selective culling, vaccination, and vaccine baits), and combined strategies (Test vaccinate/cull (TVC)), splitarea approaches using culling and vaccination, or selective culling and vaccination, and mixed scenarioswhere culling was conducted for five years and followed by vaccination or by a TVC strategy. The effectof each control strategy was evaluated over a 20-year period. Badger control was simulated in 25%, 50%,and 75% area (limited area strategy) or in the entire area (100%, wide area strategy). For endemic bTB,a culling strategy was successful in eradicating bTB from the population only if applied as an area-widestrategy. However, this was achieved only by risking the extinction of the badger population. Selectiveculling strategies (selective culling or TVC) mitigated this negative impact on the badger population’s via-bility. Furthermore, both strategies (selective culling and TVC) allowed the badger population to recovergradually, in compensation for the population reduction following the initial use of removal strategies.The model predicted that vaccination can be effective in reducing bTB prevalence in badgers, when usedin combination with culling strategies (i.e. TVC or other strategies). If fecundity was reduced below itsnatural levels (e.g. by using wildlife contraceptives), the effectiveness of vaccination strategies improved.Split-area simulations highlighted that interventions can have indirect effects (e.g. on population size) innon-treatment areas. Our model suggests that mixed control strategies could maintain infection preva-lence to a low level for a considerable period even with a growing population. The model supported thehypothesis that culling strategies appeared to be the most effective method for the control of bTB in bad-gers using parameters, where available, from ROI, either singly or in combination with other strategies. Inthis model, the success of a vaccination strategy depended partially upon population density and the pro-portion of the population infected, therefore an initial culling program (to reduce density and/or removeinfected badgers) followed by long-term vaccination may be effective in controlling bTB in badgers.