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Bovine Tuberculosis (bovine + tuberculosis)
Selected AbstractsThe spatial distribution of badgers, setts and latrines: the risk for intra-specific and badger-livestock disease transmissionECOGRAPHY, Issue 4 2008Monika Böhm The spatial distribution of wildlife hosts and the associated environmental distribution of their excretory products are important factors associated with the risk of disease transmission between wildlife and livestock. At a landscape scale, heterogeneous distribution of a wildlife host will create regional hot spots for disease risk, while at the farm level, distributional patterns of wildlife excretory products as well as habitat use are of primary importance to the assessment of disease risk to livestock. In the UK, badgers have been implicated in the transmission of bovine tuberculosis to cattle. In this study, we focus on the spatial and social organization and habitat use of badgers as well as the distributions of their excretions at latrine and sett sites to assess intra- and inter-species (badger,cattle) disease risk. Across the study site, badger latrines and setts were found in prominent clusters, at distances of up to 250 and 200 m respectively. This was partly due to small-scale clustering of latrines around sett sites, so that disease risk may be higher within the vicinity of setts. The clustered distribution suggests that sites of high risk for TB transmission may be localised within farms. Exclusion of cattle from the few sett and latrine sites within their grazing pasture is therefore likely to provide an effective way of reducing the risk of disease transmission. We also found evidence of social sub-division within badger social groups based on differences in the use of main and outlier setts. This may contribute to localised clusters of infection within the badger population, resulting in heterogeneous patterns of environmental disease risk to the wider host community. A greater understanding of variation in host behaviour and its implications for patterns of disease will allow the development of more targeted and effective management strategies for wildlife disease in group-living hosts. [source] Cytotoxic T-cell responses to Mycobacterium bovis during experimental infection of cattle with bovine tuberculosisIMMUNOLOGY, Issue 2 2003Margot A. Skinner Summary Cytotoxic T-cell responses are thought to play a significant role in the host defence against mycobacterial infections. Little is understood about such responses of cattle to Mycobacterium bovis, the causative agent of bovine tuberculosis. The work described in this report demonstrates the activity of cytotoxic cells during experimental infection of cattle with M. bovis. The cytotoxic cells were found to have the ability to specifically lyse macrophages infected with M. bovis and were detected in peripheral blood lymphocytes after in vitro re-exposure to M. bovis. Cytotoxic activity was detected 4 weeks after experimental infection with M. bovis; a similar level of activity was maintained during the infection and it was mediated by both WC1+,, and CD8+ T cells. In addition, inhibition of the growth of M. bovis within infected macrophages was detected when they were exposed to cultures containing M. bovis -specific cytotoxic cells. The ability to detect cytotoxic cells after infection of cattle with M. bovis will allow their activity to be measured during vaccination trials. Correlation of cytotoxic activity with disease outcome may aid in the design of new vaccines and vaccination strategies. [source] Gamma,delta T cell subsets are differentially associated with granuloma development and organization in a bovine model of mycobacterial diseaseINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 6 2009Brandon L. Plattner Summary The characteristic lesion in bovine tuberculosis is well-organized respiratory granulomas. This is typically associated with a strong T-helper 1 biased cell-mediated immune response and eventual containment of the infection. In bovine paratuberculosis, the classic lesion is unorganized granulomatous intestinal inflammation. Clinical paratuberculosis is associated with a T-helper 2 biased humoral immune response and eventual death because of inability of the host to contain the infection. Recent reports have suggested that gamma,delta (,,) T cells play a significant role in granuloma development and/or maintenance during initial stages of infection and may influence the subsequent adaptive immune response. The objective of this study was to use an in vivo bovine model to evaluate ,, T cells during the early host immune response to mycobacterial infection. We used immunofluorescent staining, hyperspectral microscopy, and computerized assisted morphometry to evaluate staining and distribution of ,, T cells during development of organized and unorganized granulomas. Our data suggest that bovine ,, T cell subsets are differentially recruited to early infection sites, and may be instrumental during the initial antimycobacterial host immune response as well as for granuloma organization. [source] Comparative study on the consequences of culling badgers (Meles meles) on biometrics, population dynamics and movementJOURNAL OF ANIMAL ECOLOGY, Issue 4 2000F. A. M. Tuyttens 1.,Capture,mark,recapture data were used to describe the process of recovery from a typical badger removal operation (BRO) at North Nibley, Gloucestershire, UK, which was carried out as part of the government's strategy to control bovine tuberculosis. Data on biometrics, demographics and movement from this low-density disturbed population were compared with those of two nearby high-density undisturbed populations (Wytham Woods and Woodchester Park, UK) in order to study fundamental principles of population dynamics and density-dependence. 2.,Badgers moved more between social groups at North Nibley than in the other study areas, particularly in the immediate aftermath of the removal operation. 3.,Recolonization of the vacated habitat occurred in the first instance by young females. 4.,Although in the first year after the BRO no cubs had been reared in any of the culled groups, and although the shortage of sexually mature boars may have limited the reproductive output of sows in the following year, the population took only 3 years to recover to its (already lowered) preremoval density. 5.,Losses from the adult (and cub) population due to mortality or emigration were smaller at North Nibley than at the other sites. 6.,There was much evidence that during 1995 and 1996 density-dependent effects constrained the reproductive output of the high-density populations, and some support for the hypothesis that badgers exhibit the non-linear ,large mammal' type of functional response to density. 7.,Badgers at North Nibley were younger, heavier and in better condition than badgers at Wytham Woods and Woodchester Park. 8.,We argue that the disease dynamics are likely to be different in disturbed compared with undisturbed badger populations, and that this could affect the effectiveness of BROs. [source] Effects of culling on badger Meles meles spatial organization: implications for the control of bovine tuberculosisJOURNAL OF APPLIED ECOLOGY, Issue 1 2006ROSIE WOODROFFE Summary 1The incidence of bovine tuberculosis (TB) in British cattle has risen markedly over the last two decades. Failure to control the disease in cattle has been linked to the persistence of a reservoir of infection in European badgers Meles meles, a nationally protected species. Although badger culling has formed a component of British TB control policy for many years, a recent large-scale randomized field experiment found that TB incidence in cattle was no lower in areas subject to localized badger culling than in nearby areas where no experimental culls occurred. Indeed, analyses indicated that cattle incidence was higher in culled areas. 2One hypothesis advanced to explain this pattern is that localized culling disrupted badgers' territorial behaviour, potentially increasing the rate of contact between cattle and infected badgers. This study evaluated this hypothesis by investigating badger activity and spatial organization in 13 study areas subjected to different levels of culling. Badger home ranges were mapped by feeding colour-marked baits at badger dens and measuring the geographical area in which colour-marked faeces were retrieved. 3Badger home ranges were consistently larger in culling areas. Moreover, in areas not subjected to culling, home range sizes increased with proximity to the culling area boundary. Patterns of overlap between home ranges were also influenced by culling. 4Synthesis and applications. This study demonstrates that culling badgers profoundly alters their spatial organization as well as their population density. These changes have the potential to influence contact rates between cattle and badgers, both where culls occur and on adjoining land. These results may help to explain why localized badger culling appears to have failed to control cattle TB, and should be taken into account in determining what role, if any, badger culling should play in future control strategies. [source] The effects of reducing population density on contact rates between brushtail possums: implications for transmission of bovine tuberculosisJOURNAL OF APPLIED ECOLOGY, Issue 5 2002Dave Ramsey Summary 1Interactions during mating are thought to be an important mechanism for transmission of tuberculosis (Tb) Mycobacterium bovis in the brushtail possum Trichosurus vulpecula . However, little information is available on the frequency of contacts between males and females in oestrus during the breeding season, and the relationship between mating contacts and population density. 2We used radio-telemetry to record contacts between male and oestrous and non-oestrous female possums, and determined paternity of offspring using DNA analysis. This was repeated following the removal of c . 70% of the resident possums to determine the effect of reducing density on the contact rate. 3We could not detect any significant differences in the contact rate between oestrous and non-oestrous females and males, either before or after the density reduction, even when paternity was positively identified from DNA analysis. This suggests that actual mating contacts could not be distinguished from other agonistic or affiliative contact behaviours. 4Despite this, the relationships between male,female and male,male contact rates and population density were non-linear convex-up, implying that the contact rate during the breeding season did not decrease in proportion to reductions in density. This appeared to be driven by the enlargement of male ranges and a corresponding increase in male overlap of female ranges following the density reduction. 5The form of the contact rate function will influence predictions of disease spread in epidemiological models for Tb in wildlife. This has major implications for the development of tactical approaches to disease management based on such models. [source] A model of bovine tuberculosis in the badger Melesmeles: an evaluation of control strategiesJOURNAL OF APPLIED ECOLOGY, Issue 3 2001G.C. Smith Summary 1,An individual-based stochastic simulation model was used to investigate the control of bovine tuberculosis (TB) in the European badger Meles meles. Nearly all population and epidemiological parameters were derived from one study site, and the transmission of TB from badgers to cattle was included. The latter is an essential step if reactive badger control strategies are to be modelled. 2,The model appeared to underestimate slightly the rate of population recovery following widespread culling. This may have been due to simulating an isolated population with no immigration and no compensatory increase in fecundity. This should not affect the relative efficacy of each control strategy, but does require further investigation. 3,Of the historical methods of badger control, gassing and the ,clean ring' strategies were the most effective at reducing disease prevalence in the badger and cattle herd breakdown rates. These results agree with those of earlier models. 4,The proactive badger removal operation as part of the current field trial should cause a dramatic decrease in the number of cattle herd breakdowns, but also has the greatest effect on the badger population size. 5,The proactive use of a live test to detect TB, followed by vaccination, appears to reduce substantially cattle herd breakdowns and disease prevalence in the badger. 6,Three combined control strategies gave the best initial reduction in cattle herd breakdown rate and disease prevalence in the badger: (i) a proactive cull followed by reactive test and cull; (ii) a continued vaccination and proactive test and cull; and (iii) a continuous proactive test and cull. 7,The results of simulation models suggest that badger vaccination is a very good method of TB control. This is at odds with simple models and requires further investigation. [source] Death on the farm: Culling badgers in North Pembrokeshire (Respond to this article at http://www.therai.org.uk/at/debate)ANTHROPOLOGY TODAY, Issue 2 2010Pat Caplan The Welsh Assembly Government has recently announced its intention to cull all badgers from North Pembrokeshire on the grounds that they are vectors of bovine tuberculosis. This article considers some local reactions to this news, ranging from those who support the cull wholeheartedly to those who argue against it, and some of the reasons why people adopt different standpoints. The article considers a range of issues which help explain why people think as they do; these include perception of risk, ethnicity, ideas about animals and wildlife, the selective uses of both scientific literature and emotion, and finally some of the local and regional politics involved. [source] Vaccination of neonatal calves with Mycobacterium bovis BCG induces protection against intranasal challenge with virulent M. bovisCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2005J. C. Hope Summary Vaccination of neonates with Mycobacterium bovis bacillus Calmette,Guérin (BCG) may be a strategy that overcomes reduced vaccine efficacy associated with exposure to environmental mycobacteria in humans and cattle. Preliminary comparisons indicated that 2-week-old calves produced an immune response to vaccination at least as intense as that observed in adults. Subsequently, five gnotobiotic hysterotomy derived calves aged 1 day were inoculated with BCG and 3 months later were challenged intranasally with virulent M. bovis. The number of tissues with lesions and the pathological extent of these lesions was reduced significantly in vaccinates. Furthermore, lesions were evident in the lung or associated chest lymph nodes of four of five controls but none of five vaccinates. BCG vaccination reduced significantly the level of bacterial colonization. However, lesions in the head associated lymph nodes were observed in three of five BCG-vaccinated cattle. Levels of interferon gamma (IFN-,) detected by enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISPOT) in individual vaccinated animals at challenge did not correlate with subsequent resistance and in general immune responses post-challenge were lower in vaccinated calves. Low IL-10 responses were evident but IL-4 was not detected. Responses to ESAT-6 and/or CFP-10 were evident in four of four control calves that had lesions. Two of the BCG vaccinates with lesions did not produce a response to ESAT-6 and CFP-10, indicating that these antigens did not distinguish vaccinated immune animals from vaccinated animals with lesions. Overall, vaccination of neonatal calves with BCG induced significant protection against disease and has potential as a strategy for the reduction of the incidence of bovine tuberculosis. [source] | |||||||||||||