Tuberculosis In Badgers Research Articles

Defining and testing a wildlife intervention framework for exotic disease control

Abstract Outbreaks of disease at the wildlife–livestock interface may require management interventions. Where they involve exotic/non‐endemic pathogens in wildlife, then such plans may need to be rapidly conceived and implemented to prevent further disease spread. However, detailed information on the distribution of infection is likely to be absent, whilst limited resources and tools, and ethical considerations impose constraints on what is possible and proportionate. We describe four considerations to inform decision‐making on whether to intervene. With reference to two recent examples (bovine tuberculosis in badgers in an otherwise disease‐free area, and African swine fever in wild boar in central Europe), we outline six steps to guide implementation. In both examples, a Disease Control Area was defined by determining a minimum infected area (MIA) and a buffer zone based on wildlife ecology and the potential for unrecorded spread of infection. The total area was the subject of management intervention, with the level of infection used to inform adaptive management. The MIA is defined as the minimum area that could contain all infected wildlife, given our current level of information, with a surrounding buffer zone to account for the possibility of further onward spread. In our examples, the zones were defined using a combination of field data and existing knowledge of host spatial organization and movement. The MIA (plus buffer zone) approach provides a framework for optimizing the targeting of resources in a proportionate response to a disease outbreak. Where infected animals occur outside the MIA, our examples show how wildlife management has been adapted. In principle, this approach is suitable for the delivery of disease outbreak control in wildlife, whether through culling, vaccination or other forms of control.

Simulating partial vaccine protection: BCG in badgers

In wildlife disease management there are few diseases for which vaccination is a viable option. The human vaccine BCG has been used for the control of bovine tuberculosis in badgers since 2010 and is expected to increase. Understanding the long-term effects of repeated vaccination campaigns on disease prevalence is vital, but modelling thus far has generally assumed that a vaccine provides perfect protection to a proportion of the population, and that animals exposed to a repeated vaccination have a second independent chance of becoming protected. We held a workshop with experts in the field to obtain consensus over the main pathways for partial protection in the badger, and then simulated these using an established model. The available data supported the possibility that some individuals receive no benefit from the BCG vaccine, others may result in a delayed disease progression and in the remaining animals, vaccine protected the individual from any onward transmission. Simulating these pathways using different levels of overall efficacy demonstrated that partial protection leads to a reduced effect of vaccination, but in all of the identified scenarios it was still possible to eradicate disease in an isolated population with no disease introduction. We also identify those potential vaccination failures that require further investigation to determine which of our proposed pathways is the more likely.

Tuberculosis in badgers where the bovine tuberculosis epidemic is expanding in cattle in England

Bovine tuberculosis (bTB) is an important animal health and economic problem for the cattle industry and a potential zoonotic threat. Wild badgers (Meles meles) play a role on its epidemiology in some areas of high prevalence in cattle, particularly in the UK and Republic of Ireland and increasingly in parts of mainland Europe. However, little is known about the involvement of badgers in areas on the spatial edge of the cattle epidemic, where increasing prevalence in cattle is seen. Here we report the findings of a study of found-dead (mainly road-killed) badgers in six counties on the edge of the English epidemic of bTB in cattle. The overall prevalence of Mycobacterium tuberculosis complex (MTC) infection detected in the study area was 51/610 (8.3%, 95% CI 6.4–11%) with the county-level prevalence ranging from 15 to 4–5%. The MTC spoligotypes of recovered from badgers and cattle varied: in the northern part of the study area spoligotype SB0129 predominated in both cattle and badgers, but elsewhere there was a much wider range of spoligotypes found in badgers than in cattle, in which infection was mostly with the regional cattle spoligotype. The low prevalence of MTC in badgers in much of the study area, and, relative to in cattle, the lower density of sampling, make firm conclusions difficult to draw. However, with the exception of Cheshire (north-west of the study area), little evidence was found to link the expansion of the bTB epidemic in cattle in England to widespread badger infection.

Spatial and Temporal Distribution of Mycobacterium tuberculosis Complex Infection in Eurasian Badger (Meles meles) and Cattle in Asturias, Spain.

Simple SummaryThe aim of the present work was to investigate the prevalence, spatial distribution, and temporal distribution of tuberculosis in 673 free-ranging Eurasian badgers (Meles meles) and cattle from Asturias (Atlantic Spain) during a 13-year follow-up. The study objective was to assess the role of badgers as a reservoir of tuberculosis for cattle and other sympatric wild species in the region. During the follow-up, 27/639 badgers (4.23%) were positive for the Mycobacterium tuberculosis complex based on bacterial isolation, while 160/673 (23.77%) were positive based on P22 ELISA. Badger infection was spatially and temporally associated with cattle herd infection.The present work investigated the prevalence, spatial distribution, and temporal distribution of tuberculosis (TB) in free-ranging Eurasian badgers (Meles meles) and cattle in Asturias (Atlantic Spain) during a 13-year follow-up. The study objective was to assess the role of badgers as a TB reservoir for cattle and other sympatric wild species in the region. Between 2008 and 2020, 673 badgers (98 trapped and 575 killed in road traffic accidents) in Asturias were necropsied, and their tissue samples were cultured for the Mycobacterium tuberculosis complex (MTC) isolation. Serum samples were tested in an in-house indirect P22 ELISA to detect antibodies against the MTC. In parallel, data on MTC isolation and single intradermal tuberculin test results were extracted for cattle that were tested and culled as part of the Spanish National Program for the Eradication of Bovine TB. A total of 27/639 badgers (4.23%) were positive for MTC based on bacterial isolation, while 160/673 badgers (23.77%) were found to be positive with the P22 ELISA. The rate of seropositivity was higher among adult badgers than subadults. Badger TB status was spatially and temporally associated with cattle TB status. Our results cannot determine the direction of possible interspecies transmission, but they are consistent with the idea that the two hosts may exert infection pressure on each other. This study highlights the importance of the wildlife monitoring of infection and disease during epidemiological interventions in order to optimize outcomes.

A Bayesian analysis of a Test and Vaccinate or Remove study to control bovine tuberculosis in badgers (Meles meles).

A novel five year Test and Vaccinate or Remove (TVR) wildlife research intervention project in badgers (Meles meles) commenced in 2014 in a 100km2 area of Northern Ireland. It aimed to increase the evidence base around badgers and bovine TB and help create well-informed and evidence-based strategies to address the issue of cattle-to-cattle spread and spread between cattle and badgers. It involved real-time trap-side testing of captured badgers and vaccinating those that tested negative for bTB (BadgerBCG–BCG Danish 1331) and removal of those that tested bTB positive using the Dual-Path Platform VetTB test (DPP) for cervids (Chembio Diagnostic Systems, Medford, NY USA). Four diagnostic tests were utilised within the study interferon gamma release assay (IGRA), culture (clinical samples and post mortem), DPP using both whole blood and DPP using serum. BCG Sofia (SL222) was used in the final two years because of supply issues with BadgerBCG. Objectives for this study were to evaluate the performance of the DPP in field conditions and whether any trend was apparent in infection prevalence over the study period. A Bayesian latent class model of diagnostic test evaluation in the absence of a gold standard was applied to the data. Temporal variation in the sensitivity of DPP and interferon gamma release assay (IGRA) due to the impact of control measures was investigated using logistic regression and individual variability was assessed. Bayesian latent class analysis estimated DPP with serum to have a sensitivity of 0.58 (95% CrI: 0.40–0.76) and specificity of 0.97 (95% CrI: 0.95–0.98). The DPP with whole blood showed a higher sensitivity (0.69 (95% CrI: 0.48–0.88)) but similar specificity (0.98 (95% Crl: 0.96–0.99)). The change from BCG Danish to BCG Sofia significantly impacted on DPP serum test characteristics. In addition, there was weak evidence of increasing sensitivity of IGRA over time and differences in DPP test sensitivity between adults and cubs. An exponential decline model was an appropriate representation of the infection prevalence over the 5 years, with a starting prevalence of 14% (95% CrI: 0.10–0.20), and an annual reduction of 39.1% (95% CrI: 26.5–50.9). The resulting estimate of infection prevalence in year 5 of the study was 1.9% (95% CrI: 0.8–3.8). These results provide field evidence of a statistically significant reduction in badger TB prevalence supporting a TVR approach to badger intervention. They give confidence in the reliability and reproducibility in the DPP Whole Blood as a real time trap-side diagnostic test for badgers, and describe the effect of vaccination and reduced infection prevalence on test characteristics.

Bioreactor-Grown Bacillus of Calmette and Guérin (BCG) Vaccine Protects Badgers against Virulent Mycobacterium bovis When Administered Orally: Identifying Limitations in Baited Vaccine Delivery.

Bovine tuberculosis (TB) in Great Britain adversely affects animal health and welfare and is a cause of considerable economic loss. The situation is exacerbated by European badgers (Meles meles) acting as a wildlife source of recurrent Mycobacterium bovis infection to cattle. Vaccination of badgers against TB is a possible means to reduce and control bovine TB. The delivery of vaccine in oral bait holds the best prospect for vaccinating badgers over a wide geographical area. There are practical limitations over the volume and concentration of Bacillus of Calmette and Guérin (BCG) that can be prepared for inclusion in bait. The production of BCG in a bioreactor may overcome these issues. We evaluated the efficacy of oral, bioreactor-grown BCG against experimental TB in badgers. We demonstrated repeatable protection through the direct administration of at least 2.0 × 108 colony forming units of BCG to the oral cavity, whereas vaccination via voluntary consumption of bait containing the same preparation of BCG did not result in demonstrable protection at the group-level, although a minority of badgers consuming bait showed immunological responses and protection after challenge equivalent to badgers receiving oral vaccine by direct administration. The need to deliver oral BCG in the context of a palatable and environmentally robust bait appears to introduce such variation in BCG delivery to sites of immune induction in the badger as to render experimental studies variable and inconsistent.

Protective Effect of Oral BCG and Inactivated Mycobacterium bovis Vaccines in European Badgers (Meles meles) Experimentally Infected With M. bovis.

In Europe, badgers (Meles meles) are recognized as major tuberculosis (TB) reservoir hosts with the potential to transmit infection to associated cattle herds. Recent studies in Spain have demonstrated that vaccination with a heat-inactivated Mycobacterium bovis vaccine (HIMB) successfully protects captive wild boar and red deer against progressive disease. The aim of this study was to evaluate the efficacy of two oral vaccines against TB in a badger model: the live-attenuated M. bovis bacillus Calmette-Guérin BCG vaccine (Danish strain) and a HIMB vaccine. Twenty-four badgers were separated in three treatment groups: oral vaccinated with live BCG (108 CFU, n = 5), oral vaccinated with HIMB (107 CFU, n = 7), and unvaccinated controls (n = 12). All badgers were experimentally infected with M. bovis (103 CFU) by the endobronchial route targeting the right middle lung lobe. Throughout the study, clinical, immunological, pathological, and bacteriological parameters of infection were measured. Both vaccines conferred protection against experimental TB in badger, as measured by a reduction of the severity and lesion volumes. Based on these data, HIMB vaccination appears to be a promising TB oral vaccine candidate for badgers in endemic countries.

Purification and Characterisation of Badger IgA and Its Detection in the Context of Tuberculosis.

European badgers are a wildlife reservoir of bovine tuberculosis in parts of Great Britain. Accurate diagnosis of tuberculosis in badgers is important for the development of strategies for the control of the disease. Sensitive serological tests for badger TB are needed for reasons such as cost and simplicity. Assay of mucosal IgA could be useful for diagnosing respiratory pathogens such as Mycobacterium bovis and for monitoring the response to mucosal vaccination. To develop an IgA assay, we purified secretory IgA from badger bile, identifying secretory component (SC), heavy chain (HC) and light chain (LC), at 66, 46 and 27 Kda, respectively, on the basis of size comparison with other species. Monoclonal antibodies (mAbs) were generated to purified IgA. We selected two for ELISA development. The detection limit of the IgA-specific mAbs was found to be approximately 20 ng/mL when titrated against purified badger bile. One monoclonal antibody specific for badger IgA was used to detect IgA in serum and tracheal aspirate with specificity to an immunodominant antigen of M. bovis. An M. bovis infection dose-dependent IgA response was observed in experimentally infected badgers. IgA was also detected by immunohistochemistry in the lungs of bTB-infected badgers. With further characterisation, these represent new reagents for the study of the IgA response in badgers.

Analysis of Lifetime Mortality Trajectories in Wildlife Disease Research: BaSTA and Beyond

Wildlife hosts are important reservoirs of a wide range of human and livestock infections worldwide, and in some instances, wildlife populations are threatened by disease. Yet wildlife diseases are difficult to monitor, and we often lack an understanding of basic epidemiological parameters that might inform disease management and the design of targeted interventions. The impacts of disease on host survival are generally associated with age, yet traditional epidemiological models tend to use simplistic categories of host age. Mortality trajectory analysis provides the opportunity to understand age-specific impacts of disease and uncover epidemiological patterns across complete life histories. Here, we use Bayesian survival trajectory analysis (BaSTA) software to analyse capture-mark-recapture data from a population of wild badgers Meles meles naturally infected with Mycobacterium bovis, the causative agent of tuberculosis in badgers and cattle. We reveal non-constant mortality trajectories, and show that infection exaggerates an age-dependent increase in late-life mortality. This study provides evidence for actuarial senescence in badgers, a species previously believed to display constant mortality throughout life. Our case study demonstrates the application of mortality trajectory analysis in wildlife disease research, but also highlights important limitations. We recommend BaSTA for mortality trajectory analysis in epidemiological research, but also suggest combining approaches that can include diagnostic uncertainty and the movement of hosts between disease states as they age. We recommend future combinations of multi-state and multi-event modelling frameworks for complex systems incorporating age-varying disease states.

Survival of Mycobacterium bovis BCG oral vaccine during transit through a dynamic in vitro model simulating the upper gastrointestinal tract of badgers.

In developing an oral bait BCG vaccine against tuberculosis in badgers we wanted to understand the conditions of the gastrointestinal tract and their impact on vaccine viability. Conditions mimicking stomach and small-intestine caused substantial reduction in BCG viability. We performed in vivo experiments using a telemetric pH monitoring system and used the data to parameterise a dynamic in vitro system (TIM-1) of the stomach and small intestine. Some BCG died in the stomach compartment and through the duodenum and jejunum compartments. BCG survival in the stomach was greatest when bait was absent but by the time BCG reached the jejunum, BCG viability was not significantly affected by the presence of bait. Our data suggest that from a starting quantity of 2.85 ± 0.45 x 108 colony-forming units of BCG around 2 log10 may be killed before delivery to the intestinal lymphoid tissue. There are economic arguments for reducing the dose of BCG to vaccinate badgers orally. Our findings imply this could be achieved if we can protect BCG from the harsh environment of the stomach and duodenum. TIM-1 is a valuable, non-animal model with which to evaluate and optimise formulations to maximise BCG survival in the gastrointestinal tract.

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 an 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 did not affect the social behaviour and feeding habits of the vaccinated animals. BCG was cultured from 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.

Badgers as a potential source of bovine tuberculosis - first studies in Poland.

Since 2009, Poland has been recognized as a country officially free of bovine tuberculosis (BTB). However, new outbreaks are each year quoted. In many countries it has been shown that badgers (Meles meles) are a vector of Mycobacterium bovis/caprae (M.bovis/caprae) and a source of bovine tuberculosis for many domestical species, mainly for cattle. The aim of the presented study was to determine, for the first time in Poland, the occurrence of tuberculosis in badgers in areas where the disease occurs in cattle. Tissue samples were examined by classical microbiology methods, mycobacteria growth indicator tube (MGIT), and real time PCR. A total of 155 samples from 31 badgers were examined. In any case Mycobacterium bovis/caprae infection has not been diagnosed. This indicates that badgers probably are not a vector of bovine tuberculosis in Poland.

Model of Selective and Non-Selective Management of Badgers (Meles meles) to Control Bovine Tuberculosis in Badgers and Cattle.

Bovine tuberculosis (bTB) causes substantial economic losses to cattle farmers and taxpayers in the British Isles. Disease management in cattle is complicated by the role of the European badger (Meles meles) as a host of the infection. Proactive, non-selective culling of badgers can reduce the incidence of disease in cattle but may also have negative effects in the area surrounding culls that have been associated with social perturbation of badger populations. The selective removal of infected badgers would, in principle, reduce the number culled, but the effects of selective culling on social perturbation and disease outcomes are unclear. We used an established model to simulate non-selective badger culling, non-selective badger vaccination and a selective trap and vaccinate or remove (TVR) approach to badger management in two distinct areas: South West England and Northern Ireland. TVR was simulated with and without social perturbation in effect. The lower badger density in Northern Ireland caused no qualitative change in the effect of management strategies on badgers, although the absolute number of infected badgers was lower in all cases. However, probably due to differing herd density in Northern Ireland, the simulated badger management strategies caused greater variation in subsequent cattle bTB incidence. Selective culling in the model reduced the number of badgers killed by about 83% but this only led to an overall benefit for cattle TB incidence if there was no social perturbation of badgers. We conclude that the likely benefit of selective culling will be dependent on the social responses of badgers to intervention but that other population factors including badger and cattle density had little effect on the relative benefits of selective culling compared to other methods, and that this may also be the case for disease management in other wild host populations.

Behaviour of European badgers and non-target species towards candidate baits for oral delivery of a tuberculosis vaccine

In the UK and the Republic of Ireland, the European badger (Meles meles) is a maintenance host for Mycobacterium bovis, and may transmit the infection to cattle causing bovine tuberculosis (TB). Vaccination of badgers using an injectable Bacillus Calmette-Guerin (BCG) vaccine is undertaken in some areas of the UK with the intention of interrupting this transmission, and vaccination research is underway in Ireland. An oral badger TB vaccine is also under development. We investigated the behaviour of badgers and non-target wildlife species towards three candidate baits being considered for delivering BCG to badgers orally. Bait preference was investigated by recording removal rates of baits and through the use of video surveillance at 16 badger setts. We found high variation in rates of bait removal by badgers among setts but no significant differences in removal rates among bait types or in preference behaviour from video footage. Variation in bait removal among setts correlated with the number of nights on which badgers were seen at the sett, with most baits being removed where badgers were seen on >50% of nights during the ten-day study period. Relatively few baits were removed at setts with low levels of recorded badger activity. Monitoring badger activity prior to bait deployment may therefore be useful in increasing bait uptake and vaccine coverage. Bait removal by badgers increased over the ten-day study period, suggesting initial neophobic behaviour at some setts and that a period of ‘pre-feeding’ may be required prior to vaccine deployment. Our results indicate that all three candidate baits are attractive to badgers. Removal of baits by non-target wildlife species was generally low, but varied among bait types, with smaller baits in packaging less likely to be removed. Enclosing baits in packaging is likely to deter non-target species, although in some cases non-target species did remove up to 13% of packaged baits.

Effect of culling and vaccination on bovine tuberculosis infection in a European badger (Meles meles) population by spatial simulation modelling

The control of bovine tuberculosis (bTB) in cattle herds in the Republic of Ireland (ROI) is partially hindered by spill-back infection from wild badgers (Meles meles). The aim of this study was to determine the relative effects of interventions (combinations of culling and/or vaccination) on bTB dynamics in an Irish badger population. A spatial agent-based stochastic simulation model was developed to evaluate the effect 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)), split area approaches using culling and vaccination, or selective culling and vaccination, and mixed scenarios where culling was conducted for five years and followed by vaccination or by a TVC strategy. The effect of 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-wide strategy. However, this was achieved only by risking the extinction of the badger population. Selective culling strategies (selective culling or TVC) mitigated this negative impact on the badger population’s viability. Furthermore, both strategies (selective culling and TVC) allowed the badger population to recover gradually, 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 used in combination with culling strategies (i.e. TVC or other strategies). If fecundity was reduced below its natural 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) in non-treatment areas. Our model suggests that mixed control strategies could maintain infection prevalence to a low level for a considerable period even with a growing population. The model supported the hypothesis that culling strategies appeared to be the most effective method for the control of bTB in badgers using parameters, where available, from ROI, either singly or in combination with other strategies. In this model, the success of a vaccination strategy depended partially upon population density and the proportion of the population infected, therefore an initial culling program (to reduce density and/or remove infected badgers) followed by long-term vaccination may be effective in controlling bTB in badgers.

Coupling models of cattle and farms with models of badgers for predicting the dynamics of bovine tuberculosis (TB)

Bovine TB is a major problem for the agricultural industry in several countries. TB can be contracted and spread by species other than cattle and this can cause a problem for disease control. In the UK and Ireland, badgers are a recognised reservoir of infection and there has been substantial discussion about potential control strategies. We present a coupling of individual based models of bovine TB in badgers and cattle, which aims to capture the key details of the natural history of the disease and of both species at approximately county scale. The model is spatially explicit it follows a very large number of cattle and badgers on a different grid size for each species and includes also winter housing. We show that the model can replicate the reported dynamics of both cattle and badger populations as well as the increasing prevalence of the disease in cattle. Parameter space used as input in simulations was swept out using Latin hypercube sampling and sensitivity analysis to model outputs was conducted using mixed effect models. By exploring a large and computationally intensive parameter space we show that of the available control strategies it is the frequency of TB testing and whether or not winter housing is practised that have the most significant effects on the number of infected cattle, with the effect of winter housing becoming stronger as farm size increases. Whether badgers were culled or not explained about 5%, while the accuracy of the test employed to detect infected cattle explained less than 3% of the variance in the number of infected cattle.

The role of badgers in the epidemiology of Mycobacterium bovis infection (tuberculosis) in cattle in the United Kingdom and the Republic of Ireland: current perspectives on control strategies.

Bovine tuberculosis (TB), caused by infection with Mycobacterium bovis, is a persistent problem in cattle herds in Ireland and the United Kingdom, resulting in hardship for affected farmers and substantial ongoing national exchequer expenditure. There is irrefutable scientific evidence that badgers are a reservoir of M. bovis infection and are implicated in the transmission of infection to cattle. A range of options for the control of TB in badgers is currently available or under development including culling of badgers, vaccination of badgers and cattle, and improved biosecurity to limit contact between the two species. It is unlikely that the eradication of TB from cattle will be achieved without the reservoir of M. bovis infection in badgers being controlled. The chances of success will, however, improve with greater knowledge of the disease in both species and an understanding of the epidemiological drivers of the transmission of infection between badgers and cattle.

Vaccination against tuberculosis in badgers and cattle: an overview of the challenges, developments and current research priorities in Great Britain

Bovine tuberculosis (TB) is a significant threat to the cattle industry in England and Wales. It is widely acknowledged that a combination of measures targeting both cattle and wildlife will...

Badgers and bovine tuberculosis

What is tuberculosis in badgers? Tuberculosis in European badgers Meles meles is caused by Mycobacterium bovis, the same pathogen that causes bovine tuberculosis in cattle. Pasteurization of cows’ milk and childhood vaccination have greatly reduced human cases of bovine tuberculosis infection in the developed world, though it remains a public health challenge in many developing countries. In parts of the UK and Ireland, where bovine tuberculosis is a large and growing animal health problem, badgers are a wildlife reservoir and an important source of infection for cattle.

Modelling the impact of vaccination on tuberculosis in badgers

Tuberculosis (TB) in livestock, caused by Mycobacterium bovis, persists in many countries. In Britain, efforts to control TB through the culling of badgers (Meles meles), the principal wildlife host, have so far been unsuccessful, and there is significant interest in vaccination of badgers as an alternative or complementary strategy [corrected]. Using a simulation model, we show that where TB is self-contained within the badger population and there are no external sources of infection, limited-duration vaccination at a high level of efficacy can reduce or even eradicate TB from the badger population. However, where sources of external infection persist, benefits in TB reduction in badgers can only be achieved by ongoing, annual vaccination. Vaccination is likely to be most effective as part of an integrated disease management strategy incorporating a number of different approaches across the entire host community.