The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Richard J Delahay - One of the best experts on this subject based on the ideXlab platform.
-
Predicting Badger visits to farm yards and making predictions available to farmers
2019Co-Authors: Andrew Robertson, Richard J Delahay, Joanna Judge, G. J. Wilson, Ian J. Vernon, Robbie A McdonaldAbstract:The use of agricultural resources or environments by wildlife may result in opportunities for transmission of infections amongst wild animals, livestock and humans. Targeted use of biosecurity measures may therefore reduce disease risks, although this requires practical knowledge of where such measures would be most effective, and effective means of communicating risks so that stakeholders can make informed decisions about such investment. In parts of Europe, the European Badger Meles meles may act as a wildlife reservoir for Mycobacterium bovis, the causative agent of bovine tuberculosis, and Badger visits to farmyards may provide potential opportunities for transmission of M. bovis to cattle. Biosecurity measures are effective in reducing Badger activity in farmyards, although it is unclear which farms should be targeted with such measures. We used cameras to monitor Badger activity in 155 farmyards in south west England and Wales, and related variations in the presence and frequency of Badger visits to farm characteristics. Badgers were recorded on camera in 40% of farmyards monitored. However, the frequency of visits was highly variable, with Badgers recorded on >50% of nights in only 10% of farms. The presence of Badgers in farmyards was positively associated with the density of Badger setts, the number of feed stores and the number of cattle sheds, and negatively associated with the distance to the nearest active Badger sett, the presence of a house/dwelling and the number of cattle housed on the farm. The frequency of visits was negatively associated with the distance to the nearest active Badger sett and the number of cattle housed. Models predicted the presence/absence of Badgers in farmyards with 73% accuracy (62% sensitivity, 81% specificity, using a cut off value of 0.265). Models could not distinguish between farms with low/high frequency of visits, although farms predicted as having Badgers present typically had a higher frequency of visits than those that were not. We developed and present an interactive web based application: the Badger Farm Assessment Tool (BFAT), to allow users to enter the characteristics of a farm and generate a relative risk score describing the likelihood of Badger visits.
-
Bait uptake by wild Badgers and its implications for oral vaccination against tuberculosis
2018Co-Authors: Stephen P. Carter, Robbie A Mcdonald, Andrew Robertson, Kate L. Palphramand, Mark A. Chambers, Richard J DelahayAbstract: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.
-
Model of Selective and Non-Selective Management of Badgers (Meles meles) to Control Bovine Tuberculosis in Badgers and Cattle.
'Public Library of Science (PLoS)', 2018Co-Authors: Gc Smith, Richard J Delahay, Ra Mcdonald, Budgey RAbstract:This is the author accepted manuscript. The final version is available from Public Library of Science via the DOI in this record.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.Funding organisations were: 1. Department for Food, Environment and Rural Affairs, and 2. Department of Agriculture and Rural Development Northern Ireland. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
-
model of selective and non selective management of Badgers meles meles to control bovine tuberculosis in Badgers and cattle
PLOS ONE, 2016Co-Authors: G C Smith, Richard J Delahay, Robbie A Mcdonald, Richard BudgeyAbstract: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.
-
density and abundance of Badger social groups in england and wales in 2011 2013
Scientific Reports, 2015Co-Authors: Johanna Judge, Richard J Delahay, Gavin J Wilson, Roy Macarthur, Robbie A McdonaldAbstract:In the United Kingdom, European Badgers Meles meles are a protected species and an important wildlife reservoir of bovine tuberculosis. We conducted a survey of Badger dens (main setts) in 1614 1 km squares across England and Wales, between November 2011 and March 2013. Using main setts as a proxy for Badger social groups, the estimated mean density of Badger social groups in England and Wales was 0.485 km−2 (95% confidence interval 0.449–0.521) and the estimated abundance of social groups was 71,600 (66,400–76,900). In the 25 years since the first survey in 1985–88, the annual rate of increase in the estimated number of Badger social groups was 2.6% (2.2–2.9%), equating to an 88% (70–105%) increase across England and Wales. In England, we estimate there has been an increase of 103% (83–123%) in Badger social groups, while in Wales there has been little change (−25 to +49%).
Christl A Donnelly - One of the best experts on this subject based on the ideXlab platform.
-
ranging behaviour of Badgers meles meles vaccinated with bacillus calmette guerin
Journal of Applied Ecology, 2017Co-Authors: Rosie Woodroffe, Christl A Donnelly, Cally Ham, Seth Y B Jackson, Kelly Moyes, Kayna Chapman, Naomi G Stratton, Samantha J CartwrightAbstract:Summary Because biological systems are complex, management interventions occasionally have unintended adverse consequences. For example, attempts to control bovine tuberculosis (TB) by culling Badgers Meles meles have, under some circumstances, inadvertently increased cattle TB risks. Such harmful effects occur because culling profoundly alters Badger movement behaviour, increasing pathogen transmission both between Badgers and from Badgers to cattle. It has recently been suggested that another TB management tool, Badger vaccination with Bacillus Calmette Guerin, might provoke similar behavioural changes and hence similar harmful effects for cattle. We therefore took advantage of an existing project, which monitored 54 GPS-collared Badgers across four study sites in southwest Britain, to explore whether vaccination, or live trapping to administer vaccine, influenced Badger movement behaviour. We detected no significant effects of either vaccination or trapping on Badgers’ monthly home range size, nightly distance travelled, or frequency of trespassing in neighbouring territories. The estimated effect of vaccination on Badger home range size [2% reduction, 95% confidence interval (CI) 18% reduction – 17% increase] was statistically non-significant, but significantly smaller than that associated with both widespread (180% increase, 95% CI 70–362% increase; P < 0·001) and localised Badger culling (74% increase, 95% CI 4–191% increase; P = 0·038). Synthesis and applications. In contrast with culling, live trapping and vaccinating Badgers did not measurably alter their movement behaviour, fuelling optimism that vaccination might contribute positively to cattle tuberculosis control. Our study illustrates how existing monitoring can be exploited to assess potentially adverse effects of wildlife management.
-
Badgers prefer cattle pasture but avoid cattle implications for bovine tuberculosis control
Ecology Letters, 2016Co-Authors: Rosie Woodroffe, Christl A Donnelly, Seth Y B Jackson, Kelly Moyes, Kayna Chapman, Naomi G Stratton, Samantha J CartwrightAbstract:Effective management of infectious disease relies upon understanding mechanisms of pathogen transmission. In particular, while models of disease dynamics usually assume transmission through direct contact, transmission through environmental contamination can cause different dynamics. We used Global Positioning System (GPS) collars and proximity-sensing contact-collars to explore opportunities for transmission of Mycobacterium bovis [causal agent of bovine tuberculosis] between cattle and Badgers (Meles meles). Cattle pasture was Badgers’ most preferred habitat. Nevertheless, although collared cattle spent 2914 collar-nights in the home ranges of contact-collared Badgers, and 5380 collar-nights in the home ranges of GPS-collared Badgers, we detected no direct contacts between the two species. Simultaneous GPS-tracking revealed that Badgers preferred land > 50 m from cattle. Very infrequent direct contact indicates that Badger-to-cattle and cattle-to-Badger M. bovis transmission may typically occur through contamination of the two species’ shared environment. This information should help to inform tuberculosis control by guiding both modelling and farm management.
-
exploration of the power of routine surveillance data to assess the impacts of industry led Badger culling on bovine tuberculosis incidence in cattle herds
Veterinary Record, 2015Co-Authors: Christl A Donnelly, Ana I Bento, A V Goodchild, S H DownsAbstract:In the UK, Badgers (Meles meles) are a well-known reservoir of infection, and there has been lively debate about whether Badger culling should play a role within the British Government's strategy to control and eventually eradicate tuberculosis (TB) in cattle. The key source of information on the potential for Badger culling to reduce cattle TB in high-cattle-TB-incidence areas remains the Randomised Badger Culling Trial (RBCT). In late 2013, two pilot areas were subjected to industry-led Badger culls. These culls differed importantly from RBCT culling in that free-ranging as well as cage-trapped Badgers were shot, and culling took place over a longer time period. Their impacts will be harder to evaluate because culling was not randomised between comparable areas for subsequent comparisons of culling versus no culling. However, the authors present calculations that explore the power of routine surveillance data to assess the impacts of industry-led Badger culling on cattle TB incidence. The rollout of industry-led culling as a component of a national cattle TB control policy would be controversial. The best possible estimates of the effects of such culling on confirmed cattle TB incidence should be made available to inform all stakeholders and policy-makers.
-
Badger responses to small scale culling may compromise targeted control of bovine tuberculosis
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Jon Bielby, Christl A Donnelly, Terry Burke, Lisa C Pope, Rosie WoodroffeAbstract:Where wildlife disease requires management, culling is frequently considered but not always effective. In the British Isles, control of cattle tuberculosis (TB) is hindered by infection in wild Badger (Meles meles) populations. Large-scale Badger culling can reduce the incidence of confirmed cattle TB, but these benefits are undermined by culling-induced changes in Badger behavior (termed perturbation), which can increase transmission among Badgers and from Badgers to cattle. Test–vaccinate/remove (TVR) is a novel approach that entails testing individual Badgers for infection, vaccinating test-negative animals, and killing test-positive animals. Imperfect capture success, diagnostic sensitivity, and vaccine effectiveness mean that TVR would be expected to leave some infected and some susceptible Badgers in the population. Existing simulation models predict that TVR could reduce cattle TB if such small-scale culling causes no perturbation, but could increase cattle TB if considerable perturbation occurs. Using data from a long-term study, we show that past small-scale culling was significantly associated with four metrics of perturbation in Badgers: expanded ranging, more frequent immigration, lower genetic relatedness, and elevated prevalence of Mycobacterium bovis, the causative agent of TB. Though we could not reject the hypothesis that culling up to three Badgers per social group might avoid perturbation, we also could not reject the hypothesis that killing a single Badger prompted detectable perturbation. When considered alongside existing model predictions, our findings suggest that implementation of TVR, scheduled for 2014, risks exacerbating the TB problem rather than controlling it. Ongoing illegal Badger culling is likewise expected to increase cattle TB risks.
-
localized reactive Badger culling increases risk of bovine tuberculosis in nearby cattle herds
Biology Letters, 2012Co-Authors: Flavie Vial, Christl A DonnellyAbstract:Human and livestock diseases can be difficult to control where infection persists in wildlife populations. Control of bovine tuberculosis (bTB) in British cattle is complicated by the maintenance of Mycobacterium bovis (the causative agent of bTB) in Badgers, acting as reservoirs of infection. Although over 20 000 Badgers were culled to control bTB between 1975 and 1997, the incidence of bTB in cattle has substantially increased in parts of Great Britain in recent decades. Our case-control study, involving 1208 cattle herds, provides further evidence of the detrimental effect of localized reactive Badger culling in response to the disclosure of a confirmed bTB herd breakdown in cattle. The presence of any reactive Badger culling activity and increased numbers of Badgers culled in the vicinity of a herd were associated with significantly increased bTB risk, even after adjusting for other important local risk factors. Such findings may partly explain why some earlier localized approaches to bTB control were ineffective.
Rosie Woodroffe - One of the best experts on this subject based on the ideXlab platform.
-
ranging behaviour of Badgers meles meles vaccinated with bacillus calmette guerin
Journal of Applied Ecology, 2017Co-Authors: Rosie Woodroffe, Christl A Donnelly, Cally Ham, Seth Y B Jackson, Kelly Moyes, Kayna Chapman, Naomi G Stratton, Samantha J CartwrightAbstract:Summary Because biological systems are complex, management interventions occasionally have unintended adverse consequences. For example, attempts to control bovine tuberculosis (TB) by culling Badgers Meles meles have, under some circumstances, inadvertently increased cattle TB risks. Such harmful effects occur because culling profoundly alters Badger movement behaviour, increasing pathogen transmission both between Badgers and from Badgers to cattle. It has recently been suggested that another TB management tool, Badger vaccination with Bacillus Calmette Guerin, might provoke similar behavioural changes and hence similar harmful effects for cattle. We therefore took advantage of an existing project, which monitored 54 GPS-collared Badgers across four study sites in southwest Britain, to explore whether vaccination, or live trapping to administer vaccine, influenced Badger movement behaviour. We detected no significant effects of either vaccination or trapping on Badgers’ monthly home range size, nightly distance travelled, or frequency of trespassing in neighbouring territories. The estimated effect of vaccination on Badger home range size [2% reduction, 95% confidence interval (CI) 18% reduction – 17% increase] was statistically non-significant, but significantly smaller than that associated with both widespread (180% increase, 95% CI 70–362% increase; P < 0·001) and localised Badger culling (74% increase, 95% CI 4–191% increase; P = 0·038). Synthesis and applications. In contrast with culling, live trapping and vaccinating Badgers did not measurably alter their movement behaviour, fuelling optimism that vaccination might contribute positively to cattle tuberculosis control. Our study illustrates how existing monitoring can be exploited to assess potentially adverse effects of wildlife management.
-
Badgers prefer cattle pasture but avoid cattle implications for bovine tuberculosis control
Ecology Letters, 2016Co-Authors: Rosie Woodroffe, Christl A Donnelly, Seth Y B Jackson, Kelly Moyes, Kayna Chapman, Naomi G Stratton, Samantha J CartwrightAbstract:Effective management of infectious disease relies upon understanding mechanisms of pathogen transmission. In particular, while models of disease dynamics usually assume transmission through direct contact, transmission through environmental contamination can cause different dynamics. We used Global Positioning System (GPS) collars and proximity-sensing contact-collars to explore opportunities for transmission of Mycobacterium bovis [causal agent of bovine tuberculosis] between cattle and Badgers (Meles meles). Cattle pasture was Badgers’ most preferred habitat. Nevertheless, although collared cattle spent 2914 collar-nights in the home ranges of contact-collared Badgers, and 5380 collar-nights in the home ranges of GPS-collared Badgers, we detected no direct contacts between the two species. Simultaneous GPS-tracking revealed that Badgers preferred land > 50 m from cattle. Very infrequent direct contact indicates that Badger-to-cattle and cattle-to-Badger M. bovis transmission may typically occur through contamination of the two species’ shared environment. This information should help to inform tuberculosis control by guiding both modelling and farm management.
-
Badger responses to small scale culling may compromise targeted control of bovine tuberculosis
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Jon Bielby, Christl A Donnelly, Terry Burke, Lisa C Pope, Rosie WoodroffeAbstract:Where wildlife disease requires management, culling is frequently considered but not always effective. In the British Isles, control of cattle tuberculosis (TB) is hindered by infection in wild Badger (Meles meles) populations. Large-scale Badger culling can reduce the incidence of confirmed cattle TB, but these benefits are undermined by culling-induced changes in Badger behavior (termed perturbation), which can increase transmission among Badgers and from Badgers to cattle. Test–vaccinate/remove (TVR) is a novel approach that entails testing individual Badgers for infection, vaccinating test-negative animals, and killing test-positive animals. Imperfect capture success, diagnostic sensitivity, and vaccine effectiveness mean that TVR would be expected to leave some infected and some susceptible Badgers in the population. Existing simulation models predict that TVR could reduce cattle TB if such small-scale culling causes no perturbation, but could increase cattle TB if considerable perturbation occurs. Using data from a long-term study, we show that past small-scale culling was significantly associated with four metrics of perturbation in Badgers: expanded ranging, more frequent immigration, lower genetic relatedness, and elevated prevalence of Mycobacterium bovis, the causative agent of TB. Though we could not reject the hypothesis that culling up to three Badgers per social group might avoid perturbation, we also could not reject the hypothesis that killing a single Badger prompted detectable perturbation. When considered alongside existing model predictions, our findings suggest that implementation of TVR, scheduled for 2014, risks exacerbating the TB problem rather than controlling it. Ongoing illegal Badger culling is likewise expected to increase cattle TB risks.
-
social group size affects mycobacterium bovis infection in european Badgers meles meles
Journal of Animal Ecology, 2009Co-Authors: Rosie Woodroffe, C L Cheeseman, Terry Burke, Christl A Donnelly, D R Cox, G Gettinby, John F Bourne, Gao Wei, Roger K Butlin, Peter GilksAbstract:1. In most social animals, the prevalence of directly transmitted pathogens increases in larger groups and at higher population densities. Such patterns are predicted by models of Mycobacterium bovis infection in European Badgers (Meles meles). 2. We investigated the relationship between Badger abundance and M. bovis prevalence, using data on 2696 adult Badgers in 10 populations sampled at the start of the Randomized Badger Culling Trial. 3. M. bovis prevalence was consistently higher at low Badger densities and in small social groups. M. bovis prevalence was also higher among Badgers whose genetic profiles suggested that they had immigrated into their assigned social groups. 4. The association between high M. bovis prevalence and small Badger group size appeared not to have been caused by previous small-scale culling in study areas, which had been suspended, on average, 5 years before the start of the current study. 5. The observed pattern of prevalence might occur through Badgers in smaller groups interacting more frequently with members of neighbouring groups; detailed behavioural data are needed to test this hypothesis. Likewise, longitudinal data are needed to determine whether the size of infected groups might be suppressed by disease-related mortality. 6. Although M. bovis prevalence was lower at high population densities, the absolute number of infected Badgers was higher. However, this does not necessarily mean that the risk of M. bovis transmission to cattle is highest at high Badger densities, since transmission risk depends on Badger behaviour as well as on Badger density.
-
bovine tuberculosis in cattle and Badgers in localized culling areas
Journal of Wildlife Diseases, 2009Co-Authors: Rosie Woodroffe, C L Cheeseman, Helen E. Jenkins, Christl A Donnelly, John F Bourne, Peter Gilks, Thomas W Johnston, Andrea Le M Fevre, R S CliftonhadleyAbstract:Bovine tuberculosis (TB) is a zoonotic disease that can have serious consequences for cattle farming and, potentially, for public health. In Britain, failure to control bovine TB has been linked to persistent infection of European Badger (Meles meles) populations. However, culling of Badgers in the vicinity of recent TB outbreaks in cattle has failed to reduce the overall incidence of cattle TB. Using data from a large-scale study conducted in 1998-2005, we show that Badgers collected on such localized culls had elevated prevalence of Mycobacterium bovis, the causative agent of bovine TB, suggesting that infections in cattle and Badgers were indeed associated. Moreover, there was a high degree of similarity in the M. bovis strain types isolated from cattle and associated Badgers. This similarity between strain types appeared to be unaffected by time lags between the detection of infection in cattle and culling of Badgers, or by the presence of purchased cattle that might have acquired infection elsewhere. However, localized culling appeared to prompt an increase in the prevalence of M. bovis infection in Badgers, probably by disrupting ranging and territorial behavior and hence increasing intraspecific transmission rates. This elevated prevalence among Badgers could offset the benefits, for cattle, of reduced Badger densities and may help to explain the failure of localized culling to reduce cattle TB incidence.
C L Cheeseman - One of the best experts on this subject based on the ideXlab platform.
-
long term temporal trends and estimated transmission rates for mycobacterium bovis infection in an undisturbed high density Badger meles meles population
Epidemiology and Infection, 2013Co-Authors: Richard J Delahay, Neil J Walker, C L Cheeseman, Alexandra J Tomlinson, R S Cliftonhadley, G S Smith, D Wilkinson, Mark A. ChambersAbstract:We describe epidemiological trends in Mycobacterium bovis infection in an undisturbed wild Badger (Meles meles) population. Data were derived from the capture, clinical sampling and serological testing of 1803 Badgers over 9945 capture events spanning 24 years. Incidence and prevalence increased over time, exhibiting no simple relationship with host density. Potential explanations are presented for a marked increase in the frequency of positive serological test results. Transmission rates (R0) estimated from empirical data were consistent with modelled estimates and robust to changes in test sensitivity and the spatial extent of the population at risk. The risk of a positive culture or serological test result increased with Badger age, and varied seasonally. Evidence consistent with progressive disease was found in cubs. This study demonstrates the value of long-term data and the repeated application of imperfect diagnostic tests as indices of infection to reveal epidemiological trends in M. bovis infection in Badgers.
-
culling induced changes in Badger meles meles behaviour social organisation and the epidemiology of bovine tuberculosis
PLOS ONE, 2011Co-Authors: Philip Riordan, Richard J Delahay, C L Cheeseman, Paul J Johnson, David W MacdonaldAbstract:In the UK, attempts since the 1970s to control the incidence of bovine tuberculosis (bTB) in cattle by culling a wildlife host, the European Badger (Meles meles), have produced equivocal results. Culling-induced social perturbation of Badger populations may lead to unexpected outcomes. We test predictions from the ‘perturbation hypothesis’, determining the impact of culling operations on Badger populations, movement of surviving individuals and the influence on the epidemiology of bTB in Badgers using data dervied from two study areas within the UK Government's Randomised Badger Culling Trial (RBCT). Culling operations did not remove all individuals from setts, with between 34–43% of Badgers removed from targeted social groups. After culling, bTB prevalence increased in Badger social groups neighbouring removals, particularly amongst cubs. Seventy individual adult Badgers were fitted with radio-collars, yielding 8,311 locational fixes from both sites between November 2001 and December 2003. Home range areas of animals surviving within removed groups increased by 43.5% in response to culling. Overlap between summer ranges of individuals from Neighbouring social groups in the treatment population increased by 73.3% in response to culling. The movement rate of individuals between social groups was low, but increased after culling, in Removed and Neighbouring social groups. Increased bTB prevalence in Neighbouring groups was associated with Badger movements both into and out of these groups, although none of the moving individuals themselves tested positive for bTB. Significant increases in both the frequency of individual Badger movements between groups and the emergence of bTB were observed in response to culling. However, no direct evidence was found to link the two phenomena. We hypothesise that the social disruption caused by culling may not only increase direct contact and thus disease transmission between surviving Badgers, but may also increase social stress within the surviving population, causing immunosuppression and enhancing the expression of disease.
-
social group size affects mycobacterium bovis infection in european Badgers meles meles
Journal of Animal Ecology, 2009Co-Authors: Rosie Woodroffe, C L Cheeseman, Terry Burke, Christl A Donnelly, D R Cox, G Gettinby, John F Bourne, Gao Wei, Roger K Butlin, Peter GilksAbstract:1. In most social animals, the prevalence of directly transmitted pathogens increases in larger groups and at higher population densities. Such patterns are predicted by models of Mycobacterium bovis infection in European Badgers (Meles meles). 2. We investigated the relationship between Badger abundance and M. bovis prevalence, using data on 2696 adult Badgers in 10 populations sampled at the start of the Randomized Badger Culling Trial. 3. M. bovis prevalence was consistently higher at low Badger densities and in small social groups. M. bovis prevalence was also higher among Badgers whose genetic profiles suggested that they had immigrated into their assigned social groups. 4. The association between high M. bovis prevalence and small Badger group size appeared not to have been caused by previous small-scale culling in study areas, which had been suspended, on average, 5 years before the start of the current study. 5. The observed pattern of prevalence might occur through Badgers in smaller groups interacting more frequently with members of neighbouring groups; detailed behavioural data are needed to test this hypothesis. Likewise, longitudinal data are needed to determine whether the size of infected groups might be suppressed by disease-related mortality. 6. Although M. bovis prevalence was lower at high population densities, the absolute number of infected Badgers was higher. However, this does not necessarily mean that the risk of M. bovis transmission to cattle is highest at high Badger densities, since transmission risk depends on Badger behaviour as well as on Badger density.
-
bovine tuberculosis in cattle and Badgers in localized culling areas
Journal of Wildlife Diseases, 2009Co-Authors: Rosie Woodroffe, C L Cheeseman, Helen E. Jenkins, Christl A Donnelly, John F Bourne, Peter Gilks, Thomas W Johnston, Andrea Le M Fevre, R S CliftonhadleyAbstract:Bovine tuberculosis (TB) is a zoonotic disease that can have serious consequences for cattle farming and, potentially, for public health. In Britain, failure to control bovine TB has been linked to persistent infection of European Badger (Meles meles) populations. However, culling of Badgers in the vicinity of recent TB outbreaks in cattle has failed to reduce the overall incidence of cattle TB. Using data from a large-scale study conducted in 1998-2005, we show that Badgers collected on such localized culls had elevated prevalence of Mycobacterium bovis, the causative agent of bovine TB, suggesting that infections in cattle and Badgers were indeed associated. Moreover, there was a high degree of similarity in the M. bovis strain types isolated from cattle and associated Badgers. This similarity between strain types appeared to be unaffected by time lags between the detection of infection in cattle and culling of Badgers, or by the presence of purchased cattle that might have acquired infection elsewhere. However, localized culling appeared to prompt an increase in the prevalence of M. bovis infection in Badgers, probably by disrupting ranging and territorial behavior and hence increasing intraspecific transmission rates. This elevated prevalence among Badgers could offset the benefits, for cattle, of reduced Badger densities and may help to explain the failure of localized culling to reduce cattle TB incidence.
-
genetic evidence that culling increases Badger movement implications for the spread of bovine tuberculosis
Molecular Ecology, 2007Co-Authors: Lisa C Pope, Richard J Delahay, C L Cheeseman, Rosie Woodroffe, Roger K Butlin, Gavin J Wilson, Kristien Erven, Chris M Conyers, Tanya Franklin, Terry BurkeAbstract:The Eurasian Badger (Meles meles) has been implicated in the transmission of bovine tuberculosis (TB, caused by Mycobacterium bovis) to cattle. However, evidence suggests that attempts to reduce the spread of TB among cattle in Britain by culling Badgers have mixed effects. A large-scale field experiment (the randomized Badger culling trial, RBCT) showed that widespread proactive Badger culling reduced the incidence of TB in cattle within culled areas but that TB incidence increased in adjoining areas. Additionally, localized reactive Badger culling increased the incidence of TB in cattle. It has been suggested that culling-induced perturbation of Badger social structure may increase individual movements and elevate the risk of disease transmission between Badgers and cattle. Field studies support this hypothesis, by demonstrating increases in Badger group ranges and the prevalence of TB infection in Badgers following culling. However, more evidence on the effect of culling on Badger movements is needed in order to predict the epidemiological consequences of this control strategy. Here, analysis of the genetic signatures of Badger populations in the RBCT revealed increased dispersal following culling. While standard tests provided evidence for greater dispersal after culling, a novel method indicated that this was due to medium- and long-distance dispersal, in addition to previously reported increases in home-range size. Our results also indicated that, on average, Badgers infected with M. bovis moved significantly farther than did uninfected Badgers. A disease control strategy that included culling would need to take account of the potentially negative epidemiological consequences of increased Badger dispersal.
G Gettinby - One of the best experts on this subject based on the ideXlab platform.
-
social group size affects mycobacterium bovis infection in european Badgers meles meles
Journal of Animal Ecology, 2009Co-Authors: Rosie Woodroffe, C L Cheeseman, Terry Burke, Christl A Donnelly, D R Cox, G Gettinby, John F Bourne, Gao Wei, Roger K Butlin, Peter GilksAbstract:1. In most social animals, the prevalence of directly transmitted pathogens increases in larger groups and at higher population densities. Such patterns are predicted by models of Mycobacterium bovis infection in European Badgers (Meles meles). 2. We investigated the relationship between Badger abundance and M. bovis prevalence, using data on 2696 adult Badgers in 10 populations sampled at the start of the Randomized Badger Culling Trial. 3. M. bovis prevalence was consistently higher at low Badger densities and in small social groups. M. bovis prevalence was also higher among Badgers whose genetic profiles suggested that they had immigrated into their assigned social groups. 4. The association between high M. bovis prevalence and small Badger group size appeared not to have been caused by previous small-scale culling in study areas, which had been suspended, on average, 5 years before the start of the current study. 5. The observed pattern of prevalence might occur through Badgers in smaller groups interacting more frequently with members of neighbouring groups; detailed behavioural data are needed to test this hypothesis. Likewise, longitudinal data are needed to determine whether the size of infected groups might be suppressed by disease-related mortality. 6. Although M. bovis prevalence was lower at high population densities, the absolute number of infected Badgers was higher. However, this does not necessarily mean that the risk of M. bovis transmission to cattle is highest at high Badger densities, since transmission risk depends on Badger behaviour as well as on Badger density.
-
the prevalence distribution and severity of detectable pathological lesions in Badgers naturally infected with mycobacterium bovis
Epidemiology and Infection, 2008Co-Authors: Helen E. Jenkins, R S Cliftonhadley, Christl A Donnelly, W T Johnston, F J Bourne, D R Cox, G Gettinby, J P Mcinerney, W I Morrison, Gavin WatkinsAbstract:The Randomized Badger Culling Trial (RBCT) began in 1998 to determine the impact of Badger culling in controlling bovine tuberculosis in cattle. A total of 1166 Badgers (14% of total) proactively culled during the RBCT were found to be tuberculous, offering a unique opportunity to study the pathology caused by Mycobacterium bovis in a large sample of Badgers. Of these, 39% of adults (~6% of all adults culled) had visible lesions (detectable at necropsy) of bovine tuberculosis; cubs had a lower prevalence of infection (9%) but a higher percentage of tuberculous cubs (55·5%) had visible lesions. Only ~1% of adult Badgers had extensive, severe pathology. Tuberculous Badgers with recorded bite wounds (~5%) had a higher prevalence of visible lesions and a different distribution of lesions, suggesting transmission via bite wounds. However, the predominance of lesions in the respiratory tract indicates that most transmission occurs by the respiratory route.
-
effects of culling on spatial associations of mycobacterium bovis infections in Badgers and cattle
Journal of Applied Ecology, 2007Co-Authors: Helen E. Jenkins, C L Cheeseman, Rosie Woodroffe, R S Cliftonhadley, Christl A Donnelly, W T Johnston, F J Bourne, D R Cox, G Gettinby, Peter GilksAbstract:Bovine tuberculosis (TB), caused by Mycobacterium bovis, has serious consequences for Britain's cattle industry. European Badgers (Meles meles) can transmit infection to cattle, and for many years the British government culled Badgers in a series of attempts to reduce cattle infections. We investigated the impact of Badger culling on the spatial distribution of M. bovis infection in Badger and cattle populations in replicated areas in England. M. bovis infection was significantly clustered within Badger populations, but clustering was reduced when culls were repeated across wide areas. A significant spatial association between M. bovis infections in Badgers and cattle herds likewise declined across successive culls. These patterns are consistent with evidence that Badgers are less territorial and range more widely in culled areas, allowing transmission to occur over greater distances. Prior to culling, M. bovis infections were clustered within cattle populations. Where Badger culling was localised, and in unculled areas just outside widespread culling areas, cattle infections became less spatially clustered as Badger culling was repeated. This is consistent with expanded Badger ranging observed in these areas. In contrast, clustering of infection in cattle persisted over time on lands where Badgers were repeatedly culled over wide areas. While this lack of a temporal trend must be interpreted with caution, it might reflect persistent infection within, and continued transmission between, cattle herds in areas where transmission from Badgers to cattle had been reduced by Badger culling. Continued spatial association of infections in cattle and Badgers in such areas might partly reflect transmission from cattle. Synthesis and applications: Our findings confirm that Badger culling can prompt spatial spread of M. bovis infection, a phenomenon likely to undermine the utility of this approach as a disease control measure. Possible evidence of transmission from cattle, both to other cattle and to Badgers, suggests that improved cattle controls might yield multiple benefits for TB management.
-
Effects of culling on Badger abundance: implications for tuberculosis control
Journal of Zoology, 2007Co-Authors: R. Woodroffe, C L Cheeseman, W T Johnston, F J Bourne, D R Cox, G Gettinby, P. Gilks, A. M. Le Fevre, C. A. Donnelly, J P McinerneyAbstract:Culling is often considered as a tool for controlling wildlife diseases that can also infect people or livestock. Culling European Badgers Meles meles can cause both positive and negative effects on the incidence of bovine tuberculosis (TB) in cattle. One factor likely to influence the outcome of different Badger culling strategies for cattle TB is the reduction in Badger population density achieved. However, this reduction is difficult to measure because Badgers, being nocturnal and fossorial, are difficult to count. Here, we use indices of Badger abundance to measure the population impacts of two culling strategies tested in Britain. The densities of Badger setts and latrines recorded before culling were correlated with the densities of Badgers captured on initial culls, suggesting that both were indices of actual Badger abundance. Widespread 'proactive' culling was associated with a 73% reduction in the density of Badger latrines, a 69% reduction in the density of active burrows and a 73% reduction in the density of road killed Badgers. This population reduction was achieved by a coordinated effort entailing widespread and repeated trapping over several years. However, this strategy caused only modest reductions in cattle TB incidence in culled areas and elevated incidence in neighbouring unculled areas. Localized 'reactive' culling caused a 26% reduction in latrine density, a 32% reduction in active burrow density and a 10% reduction in the density of road killed Badgers, but apparently increased the incidence of cattle TB. These results indicate that the relationship between Badger population reduction and TB transmission to cattle is strongly non linear, probably because culling prompts changes in Badger behaviour that influence transmission rates. These findings raise serious questions about the capacity of Badger culling to contribute to the control of cattle TB in Britain
-
culling and cattle controls influence tuberculosis risk for Badgers
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Rosie Woodroffe, Richard J Delahay, C L Cheeseman, Helen E. Jenkins, R S Cliftonhadley, Christl A Donnelly, D R Cox, John F Bourne, Thomas W Johnston, G GettinbyAbstract:Human and livestock diseases can be difficult to control where infection persists in wildlife populations. In Britain, European Badgers (Meles meles) are implicated in transmitting Mycobacterium bovis, the causative agent of bovine tuberculosis (TB), to cattle. Badger culling has therefore been a component of British TB control policy for many years. However, large-scale field trials have recently shown that Badger culling has the capacity to cause both increases and decreases in cattle TB incidence. Here, we show that repeated Badger culling in the same area is associated with increasing prevalence of M. bovis infection in Badgers, especially where landscape features allow Badgers from neighboring land to recolonize culled areas. This impact on prevalence in Badgers might reduce the beneficial effects of culling on cattle TB incidence, and could contribute to the detrimental effects that have been observed. Additionally, we show that suspension of cattle TB controls during a nationwide epidemic of foot and mouth disease, which substantially delayed removal of TB-affected cattle, was associated with a widespread increase in the prevalence of M. bovis infection in Badgers. This pattern suggests that infection may be transmitted from cattle to Badgers, as well as vice versa. Clearly, disease control measures aimed at either host species may have unintended consequences for transmission, both within and between species. Our findings highlight the need for policymakers to consider multiple transmission routes when managing multihost pathogens.
