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1.
In France, several surveillance programmes have been carried out to monitor the presence of bovine tuberculosis (bTB) in badgers in regions where cattle or wildlife show high bTB prevalence (Seine-Maritime, Côte d’Or, Dordogne/Charente). Diagnostic methods include post-mortem examination, polymerase chain reaction (PCR) and/or microbiological culture. The frequency of visible lesions was significantly higher in Dordogne/Charente (14/283, 4.9 %) than in Côte d’Or (19/1146, 1.7 %) and Seine-Maritime (2/160, 1.25 %) (Fisher’s exact test, p?<?0.001). Lesions were mainly located in cephalic and thoracic lymph nodes with one badger showing generalised tuberculosis. Near infected cattle farms or pastures, Mycobacterium bovis was detected using the culture method in roughly 1 % (1/103) of the badgers sampled in Seine-Maritime and in 5.6 % (49/878) of the badgers sampled in Côte d’Or. In Dordogne/Charente, the prevalence determined by PCR was 13.3 % (29/218). M. bovis was not found in badgers trapped in areas where there are no infected cattle. Spoligotyping and multiple locus variable number tandem repeat analysis showed that all M. bovis strains isolated from badgers were of the same genotype as those isolated from cattle in the vicinity, demonstrating an epidemiological link between both species. These are the first cases of bTB in badgers reported in France. Further surveys and research are needed to investigate the role badgers play in the epidemiology of bTB.  相似文献   

2.
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.  相似文献   

3.

Background

Badgers are involved in the transmission to cattle of bovine tuberculosis (TB), a serious problem for the UK farming industry. Cross-sectional studies have shown an association between bite wounds and TB infection in badgers which may have implications for M. bovis transmission and control, although the sequence of these two events is unclear. Transmission during aggressive encounters could potentially reduce the effectiveness of policies which increase the average range of a badger and thus its opportunities for interaction with other social groups.

Methods

Data were obtained on badgers captured during a long term study at Woodchester Park, UK (1998–2006). Many badgers had multiple observations. At each observation, the badger was assigned a “state” depending on presence of bite wounds and/or TB infection. Hence each badger had a “transition” from the previous state to the current state. We calculated the numbers of each type of transition and the time spent in each state. Transition rates were calculated for each transition category, dividing the number of such transitions by the total time at risk. We compared the rate of bite wound acquisition in infected badgers with that for uninfected badgers and the rate of positive M.bovis test results in bitten badgers with that in unbitten badgers.

Results

The rate of bite wound acquisition in infected badgers (0.291 per year) was 2.09 (95% CI: 1.41, 3.08) times that in uninfected badgers (0.139 per year). The rate of positive M.bovis test results in bitten badgers (0.097 per year) was 2.45 (95% CI: 1.29, 4.65) times that in unbitten badgers (0.040 per year).

Conclusions

We found strong evidence of both potential sequences of events consistent with transmission via bite wounds and distinctive behaviour in infected badgers. The complex relationship between behaviour and infection must be considered when planning TB control strategies.  相似文献   

4.
Forty-five badgers representing five social groups were removed from an area in Staffordshire where tuberculosis had occurred in cattle. Prior to removal, the tuberculosis status of the badger population was investigated by screening faeces samples, collected at fortnightly intervals, and badger social-group territories were determined by bait-marking. Samples for cultural and biological examination were taken from the live badgers before euthanasia and detailed post-mortem examination. The adult badger population density was 6-2/km2 and Mycobacterium bovis was isolated from samples taken post mortem from eight (17-8%) badgers. The results are reviewed in relation to previous findings.  相似文献   

5.
A long-term research programme has been underway in Ireland to evaluate the usefulness of badger vaccination as part of the national bTB (bovine tuberculosis) control strategy. This culminated in a field trial which commenced in county Kilkenny in 2009 to determine the effects of badger vaccination on Mycobacterium bovis transmission in badgers under field conditions. In the present study, we sought to optimise the characteristics of a multiplex chemiluminescent assay for detection of M. bovis infection in live badgers. Our goal was to maximise specificity, and therefore statistical power, during evaluation of the badger vaccine trial data. In addition, we also aimed to explore the effects of vaccination on test characteristics. For the test optimisation, we ran a stepwise logistic regression with analytical weights on the converted Relative Light Units (RLU) obtained from testing blood samples from 215 badgers captured as part of culling operations by the national Department of Agriculture, Food and the Marine (DAFM). The optimised test was applied to two other datasets obtained from two captive badger studies (Study 1 and Study 2), and the sensitivity and specificity of the test was attained separately for vaccinated and non-vaccinated badgers. During optimisation, test sensitivity was maximised (30.77%), while retaining specificity at 99.99%. When the optimised test was then applied to the captive badger studies data, we observed that test characteristics did not vary greatly between vaccinated and non-vaccinated badgers. However, a different time lag between infection and a positive test result was observed in vaccinated and non-vaccinated badgers. We propose that the optimized multiplex immunoassay be used to analyse the vaccine trial data. In relation to the difference in the time lag observed for vaccinated and non-vaccinated badgers, we also present a strategy to enable the test to be used during trial evaluation.  相似文献   

6.
Behavioural investigations into the transmission of bovine tuberculosis (Mycobacterium bovis) between badgers and cattle suggest that badger activity in farm buildings may incur a significant risk of cross-infection. However, measures to exclude badgers from buildings have not been systematically field-tested. In the present study, remote surveillance and radio-tracking were used to monitor the effect of electric fencing manipulations on the frequency of badger incursions into feed stores and cattle housing, and on badger ranging behaviour. Electric fencing was effective in preventing access to the farm buildings where it was installed and also significantly reduced incursions into unfenced buildings. Badger home range and core activity areas tended to increase in size when the fencing was installed, although they did not extend beyond the boundaries of the relevant social group territories. We discuss the logistical constraints of using electric fencing in this context and conclude that it is a potentially useful method of reducing contact between badgers and cattle, within farm buildings and yards.  相似文献   

7.
In Great Britain and Ireland, badgers (Meles meles) are a wildlife reservoir of Mycobacterium bovis and implicated in bovine tuberculosis transmission to domestic cattle. The route of disease transmission is unknown with direct, so‐called “nose‐to‐nose,” contact between hosts being extremely rare. Camera traps were deployed for 64,464 hr on 34 farms to quantify cattle and badger visitation rates in space and time at six farm locations. Badger presence never coincided with cattle presence at the same time, with badger and cattle detection at the same location but at different times being negatively correlated. Badgers were never recorded within farmyards during the present study. Badgers utilized cattle water troughs in fields, but detections were infrequent (equivalent to one badger observed drinking every 87 days). Cattle presence at badger‐associated locations, for example, setts and latrines, were three times more frequent than badger presence at cattle‐associated locations, for example, water troughs. Preventing cattle access to badger setts and latrines and restricting badger access to cattle water troughs may potentially reduce interspecific bTB transmission through reduced indirect contact.  相似文献   

8.
Bovine tuberculosis is a disease of historical importance to human health in the UK that remains a major animal health and economic issue. Control of the disease in cattle is complicated by the presence of a reservoir species, the Eurasian badger. In spite of uncertainty in the degree to which cattle disease results from transmission from badgers, and opposition from environmental groups, culling of badgers has been licenced in two large areas in England. Methods to limit culls to smaller areas that target badgers infected with TB whilst minimising the number of uninfected badgers culled is therefore of considerable interest. Here, we use historical data from a large-scale field trial of badger culling to assess two alternative hypothetical methods of targeting TB-infected badgers based on the distribution of cattle TB incidents: (i) a simple circular ‘ring cull’; and (ii) geographic profiling, a novel technique for spatial targeting of infectious disease control that predicts the locations of sources of infection based on the distribution of linked cases. Our results showed that both methods required coverage of very large areas to ensure a substantial proportion of infected badgers were removed, and would result in many uninfected badgers being culled. Geographic profiling, which accounts for clustering of infections in badger and cattle populations, produced a small but non-significant increase in the proportion of setts with TB-infected compared to uninfected badgers included in a cull. It also provided no overall improvement at targeting setts with infected badgers compared to the ring cull. Cattle TB incidents in this study were therefore insufficiently clustered around TB-infected badger setts to design an efficient spatially targeted cull; and this analysis provided no evidence to support a move towards spatially targeted badger culling policies for bovine TB control.  相似文献   

9.
In Ireland, the badger Meles meles L is a reservoir species for Mycobacterium bovis and, as such, contributes to the maintenance of bovine tuberculosis in cattle. A previous estimate of the badger population in the Republic was 200,000 badgers. In the current study, we obtained data on badger numbers from a large-scale badger removal project (the Four-Area project). The removal areas of the Four-Area Project were surrounded by barriers (either water or buffer areas where removals were also conducted) to prevent badger immigration. Within these areas, a grid of 0.25 km2 was created within which we knew the badger numbers and habitat types (based on Corine data). Associations between badger numbers and habitat type were investigated using negative binomial modeling. Extrapolations from the model yielded an estimated badger population in the Republic of approximately 84,000 badgers. The implications of these findings are discussed.  相似文献   

10.
Landscape epidemiology analyses how environmental characteristics influence pathogen transmission between hosts of one or several species, by inducing constraints on space use by hosts, and/or on pathogen survival in the environment. Here, we analysed how environmental variables could be associated with the Mycobacterium bovis concomitant infection in both cattle and badgers, in an area of south-western France. We defined circular spatial units (500 and 1000 m radiuses) centred on 113 setts of trapped badgers and including cattle pastures. The characteristics of spatial units where only one species had been found infected were compared with the ones where both cattle and badgers had been found infected. A multivariate logistic model was used to analyse the association between concomitant infection in both species and three groups of variables describing landscape, animal population and terrain features of spatial units. The terrain ruggedness index of pastures and the percentage of sand in their soil were positively associated with the odds of concomitant infection in cattle and badgers in the spatial units. The number of neighbouring badger groups was negatively associated with the odds of concomitant infection (spatial units of 1000 m radius), whereas the number of crop parcels was positively associated with the odds of concomitant infection (spatial units of 500 m radius). These results suggest that terrain features, badger population structure and food availability may influence the spread of M. bovis infection between badgers and cattle, leading to concomitant infection of both species.  相似文献   

11.
European badgers (Meles meles) in Ireland and the UK are a reservoir for Mycobacterium bovis, the causative agent of bovine tuberculosis (TB). A number of interventions have been evaluated in attempts to control bovine TB within badger populations, and many of which rely on the capture of badgers. One strategy being implemented within Ireland is intramuscular vaccination using Bacillus Calmette-Guérin (BCG), as an alternative to badger culling. The success of vaccination as a disease control strategy depends on the ability to capture badgers and administer vaccines; thus, trapping success is crucial to effectively vaccinate the population (maximize vaccine coverage). A field vaccine trial was conducted in County Kilkenny, Ireland, from 2010–2013. We used data from this trial to evaluate the association between weather (precipitation and temperature data), badger sett characteristics, and badger trapping success. Approximately 10% of capture efforts resulted in a badger capture. Our results indicate that badger captures were the highest in drizzle, rain, and heavy rain weather conditions, and when minimum temperatures ranged from 3–8 °C. Badger captures were the highest at main setts (large burrow systems), and when sett activity scores were high (qualitative classes 4 or 5). Using local precipitation and temperature data in conjunction with observed sett characteristics provides wildlife managers with guidelines to optimize trapping success. Implementing capture operations under optimal conditions should increase the trapping success of badgers and allow for increased delivery of vaccines to manage bovine TB.  相似文献   

12.
Multi-host pathogens are particularly difficult to control, especially when at least one of the hosts acts as a hidden reservoir. Deep sequencing of densely sampled pathogens has the potential to transform this understanding, but requires analytical approaches that jointly consider epidemiological and genetic data to best address this problem. While there has been considerable success in analyses of single species systems, the hidden reservoir problem is relatively under-studied. A well-known exemplar of this problem is bovine Tuberculosis, a disease found in British and Irish cattle caused by Mycobacterium bovis, where the Eurasian badger has long been believed to act as a reservoir but remains of poorly quantified importance except in very specific locations. As a result, the effort that should be directed at controlling disease in badgers is unclear. Here, we analyse densely collected epidemiological and genetic data from a cattle population but do not explicitly consider any data from badgers. We use a simulation modelling approach to show that, in our system, a model that exploits available cattle demographic and herd-to-herd movement data, but only considers the ability of a hidden reservoir to generate pathogen diversity, can be used to choose between different epidemiological scenarios. In our analysis, a model where the reservoir does not generate any diversity but contributes to new infections at a local farm scale are significantly preferred over models which generate diversity and/or spread disease at broader spatial scales. While we cannot directly attribute the role of the reservoir to badgers based on this analysis alone, the result supports the hypothesis that under current cattle control regimes, infected cattle alone cannot sustain M. bovis circulation. Given the observed close phylogenetic relationship for the bacteria taken from cattle and badgers sampled near to each other, the most parsimonious hypothesis is that the reservoir is the infected badger population. More broadly, our approach demonstrates that carefully constructed bespoke models can exploit the combination of genetic and epidemiological data to overcome issues of extreme data bias, and uncover important general characteristics of transmission in multi-host pathogen systems.  相似文献   

13.
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.  相似文献   

14.

Background

Bovine tuberculosis caused by Mycobacterium bovis is a serious and economically important disease of cattle. Badgers have been implicated in the transmission and maintenance of the disease in the UK since the 1970s. Recent studies have provided substantial evidence of widespread and frequent visits by badgers to farm buildings during which there is the potential for close direct contact with cattle and contamination of cattle feed.

Methodology

Here we evaluated the effectiveness of simple exclusion measures in improving farm biosecurity and preventing badger visits to farm buildings. In the first phase of the study, 32 farms were surveyed using motion-triggered infrared cameras on potential entrances to farm buildings to determine the background level of badger visits experienced by each farm. In the second phase, they were divided into four treatment groups; “Control”, “Feed Storage”, “Cattle Housing” and “Both”, whereby no exclusion measures were installed, exclusion measures were installed on feed storage areas only, cattle housing only or both feed storage and cattle housing, respectively. Badger exclusion measures included sheet metal gates, adjustable metal panels for gates, sheet metal fencing, feed bins and electric fencing. Cameras were deployed for at least 365 nights in each phase on each farm.

Results

Badger visits to farm buildings occurred on 19 of the 32 farms in phase one. In phase two, the simple exclusion measures were 100% effective in preventing badger entry into farm buildings, as long as they were appropriately deployed. Furthermore, the installation of exclusion measures also reduced the level of badger visits to the rest of the farmyard. The findings of the present study clearly demonstrate how relatively simple practical measures can substantially reduce the likelihood of badger visits to buildings and reduce some of the potential for contact and disease transmission between badgers and cattle.  相似文献   

15.
Mycobacterium tuberculosis complex (MTBC) comprises closely related species responsible for human and animal tuberculosis (TB). Efficient species determination is useful for epidemiological purposes, especially for the elucidation of the zoonotic contribution. In Algeria, data on MTBC genotypes are largely unknown. In this study, we aimed to investigate the occurrence and diversity of MTBC genotypes causing human and bovine TB in Northern Algeria. During a two-year sampling period (2017–2019) in two regions of Northern Algeria, we observed an overall prevalence of 6.5% of tuberculosis (TB) among slaughtered cattle, which is higher than previous Algerian data yet comparable to neighboring countries. A total of 296 Mycobacterium tuberculosis complex (MTBC) isolates were genotyped by spoligotyping: 181 from tissues with TB-like lesions collected from 181 cattle carcasses and 115 from TB patients. In human isolates, we identified 107 M. tuberculosis, seven M. bovis and one “M. pinnipedii-like”, while for bovine samples, 174 isolates were identified as M. bovis, three as M. caprae, three as “M. pinnipedii-like” and one as “M. microti-like”. The majority of isolates (89.2%) belonged to 72 different known Shared International Types (SIT) or M. bovis spoligotypes (SB), while we also identified seven new SB profiles (SB2695 to SB2701). Twenty-eight of the SB profiles were new to Algeria. Our data suggest zoonotic transmission in Sétif, where significantly more TB was observed among cattle (20%) compared to the slaughterhouses from the three other regions (5.4%–7.3%) (p < 0.0001), with the isolation of the same M. bovis genotypes from TB patients. The present study showed a high genetic diversity of MTBC isolated from human and cattle in Northern Algeria. Even though relatively small in terms of numbers, our data suggest the zoonotic transmission of TB from cattle to humans, suggesting the need for stronger eradication strategies for bovine TB.  相似文献   

16.
Whole genome sequencing (WGS) technology holds great promise as a tool for the forensic epidemiology of bacterial pathogens. It is likely to be particularly useful for studying the transmission dynamics of an observed epidemic involving a largely unsampled ‘reservoir’ host, as for bovine tuberculosis (bTB) in British and Irish cattle and badgers. BTB is caused by Mycobacterium bovis, a member of the M. tuberculosis complex that also includes the aetiological agent for human TB. In this study, we identified a spatio-temporally linked group of 26 cattle and 4 badgers infected with the same Variable Number Tandem Repeat (VNTR) type of M. bovis. Single-nucleotide polymorphisms (SNPs) between sequences identified differences that were consistent with bacterial lineages being persistent on or near farms for several years, despite multiple clear whole herd tests in the interim. Comparing WGS data to mathematical models showed good correlations between genetic divergence and spatial distance, but poor correspondence to the network of cattle movements or within-herd contacts. Badger isolates showed between zero and four SNP differences from the nearest cattle isolate, providing evidence for recent transmissions between the two hosts. This is the first direct genetic evidence of M. bovis persistence on farms over multiple outbreaks with a continued, ongoing interaction with local badgers. However, despite unprecedented resolution, directionality of transmission cannot be inferred at this stage. Despite the often notoriously long timescales between time of infection and time of sampling for TB, our results suggest that WGS data alone can provide insights into TB epidemiology even where detailed contact data are not available, and that more extensive sampling and analysis will allow for quantification of the extent and direction of transmission between cattle and badgers.  相似文献   

17.
18.
The spatial distribution of urine and faecal scent marks of badgersMeles meles (Linnaeus, 1758) at low population density (mean±SE across 4 social groups was 5.73±0.735 badgers/km2) in south-western England were quantified. Eighteen badger latrines (greater than one dung pit containing faeces), 74 single defecations not in pits and 21 faeces in single pits were located in spring when badgers were defending well-defined territories. Woodland was selected, and arable land avoided, for latrine sites. Pasture and built-up land was selected for single defecations not in pits whereas faeces in single pits were distributed randomly across habitat types. Faecal scent marks were strongly associated with the edge of pastoral fields rather than the middle. Forty-six and 51 urinations were located in spring and summer, respectively. Urine was deposited randomly across habitat types but was concentrated at the linear features surrounding the main setts. This is the first reported use of high levels of single defecations and urinations in badger scent marking strategies in the UK. These results are discussed in relation to the potential for transmission of bovine tuberculosisMycobacterium bovis from badger excreta to cattle.  相似文献   

19.

Background

The control of bovine tuberculosis (bTB) remains a priority on the public health agenda in Great Britain, after launching in 1998 the Randomised Badger Culling Trial (RBCT) to evaluate the effectiveness of badger (Meles meles) culling as a control strategy. Our study complements previous analyses of the RBCT data (focusing on treatment effects) by presenting analyses of herd-level risks factors associated with the probability of a confirmed bTB breakdown in herds within each treatment: repeated widespread proactive culling, localized reactive culling and no culling (survey-only).

Methodology/Principal Findings

New cases of bTB breakdowns were monitored inside the RBCT areas from the end of the first proactive badger cull to one year after the last proactive cull. The risk of a herd bTB breakdown was modeled using logistic regression and proportional hazard models adjusting for local farm-level risk factors. Inside survey-only and reactive areas, increased numbers of active badger setts and cattle herds within 1500 m of a farm were associated with an increased bTB risk. Inside proactive areas, the number of M. bovis positive badgers initially culled within 1500 m of a farm was the strongest predictor of the risk of a confirmed bTB breakdown.

Conclusions/Significance

The use of herd-based models provide insights into how local cattle and badger populations affect the bTB breakdown risks of individual cattle herds in the absence of and in the presence of badger culling. These measures of local bTB risks could be integrated into a risk-based herd testing programme to improve the targeting of interventions aimed at reducing the risks of bTB transmission.  相似文献   

20.
Bovine tuberculosis (BTB) is a multi-species infection that commonly affects cattle and badgers in Great Britain. Despite years of study, the impact of badgers on BTB incidence in cattle is poorly understood. Using a two-host transmission model of BTB in cattle and badgers, we find that published data and parameter estimates are most consistent with a system at the threshold of control. The most consistent explanation for data obtained from cattle and badger populations includes within-host reproduction numbers close to 1 and between-host reproduction numbers of approximately 0.05. In terms of controlling infection in cattle, reducing cattle-to-cattle transmission is essential. In some regions, even large reductions in badger prevalence can have a modest impact on cattle infection and a multi-stranded approach is necessary that also targets badger-to-cattle transmission directly. The new perspective highlighted by this two-host approach provides insight into the control of BTB in Great Britain.  相似文献   

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