A study of tuberculosis in road traffic-killed badgers on the edge of the British bovine TB epidemic area

The role of badgers in the geographic expansion of the bovine tuberculosis (bTB) epidemic in England is unknown: indeed there have been few published studies of bTB in badgers outside of the Southwest of England where the infection is now endemic in cattle. Cheshire is now on the edge of the expanding area of England in which bTB is considered endemic in cattle. Previous studies, over a decade ago when bovine infection was rare in Cheshire, found no or only few infected badgers in the south eastern area of the county. In this study, carried out in 2014, road-killed badgers were collected through a network of local stakeholders (farmers, veterinarians, wildlife groups, government agencies), and Mycobacterium bovis was isolated from 21% (20/94) badger carcasses. Furthermore, there was strong evidence for co-localisation of M. bovis SB0129 (genotype 25) infection in both badgers and cattle herds at a county scale. While these findings suggest that both badgers and cattle are part of the same geographically expanding epidemic, the direction of any cross-species transmission and the drivers of this expansion cannot be determined. The study also demonstrated the utility of using road-killed badgers collected by stakeholders as a means of wildlife TB surveillance

Failure to detect tuberculosis in Black lechwe antelopes (Kobus leche smithemani) in Zambia

<p>Abstract</p> <p>Background</p> <p>Two types of lechwe antelopes exclusively exist in their natural ecosystems in Zambia; the Black lechwe (<it>Kobus leche smithemani</it>) and the Kafue lechwe (<it>Kobus leche kafuensis</it>). Despite inhabiting similar ecosystems, tuberculosis has been reported in Kafue lechwe without its documentation in Black lechwe antelopes. However, the past few decades have seen a drastic decline in both lechwe populations. Whereas studies have postulated that infectious diseases such as tuberculosis are having a negative impact on the Kafue lechwe population, no information is available on Black lechwe antelopes. Thus this study was conducted to investigate tuberculosis in Black lechwe antelopes of the Bangweulu swamps in comparison with the Kafue lechwe antelopes of Lochinvar.</p> <p>Findings</p> <p>A total of 44 lechwe antelopes (Black (<it>n </it>= 30): Kafue (<it>n </it>= 14) were sampled from Bangweulu and Lochinvar respectively. A positive case was defined with findings of gross lesions with Ziehl Nielsen and culture confirmation. Out of the 14 animals examined in Lochinvar, 21.4% [95% CI: 15.4, 44.4%] had necropsy lesions consistent with tuberculosis. The corresponding samples from 30 Black lechwe of Bangweulu yielded negative results on all the three tests.</p> <p>Conclusions</p> <p>Current findings from this study intimate the possible absence of tuberculosis in Black lechwe antelopes whilst confirming the presence of tuberculosis in Kafue lechwe of the Kafue basin. The absence of tuberculosis in the Black lechwe suggests that the observed population decline may not be caused by tuberculosis. However, without detailed molecular epidemiological studies it is not possible to determine the association of <it>M. bovis </it>infection in sympatric animal populations. The possible role of transmission of tuberculosis between wildlife and cattle is discussed herein. <b>Findings</b></p

Protection against Tuberculosis in Eurasian Wild Boar Vaccinated with Heat-Inactivated Mycobacterium bovis

Tuberculosis (TB) caused by Mycobacterium bovis and closely related members of the Mycobacterium tuberculosis complex continues to affect humans and animals worldwide and its control requires vaccination of wildlife reservoir species such as Eurasian wild boar (Sus scrofa). Vaccination efforts for TB control in wildlife have been based primarily on oral live BCG formulations. However, this is the first report of the use of oral inactivated vaccines for controlling TB in wildlife. In this study, four groups of 5 wild boar each were vaccinated with inactivated M. bovis by the oral and intramuscular routes, vaccinated with oral BCG or left unvaccinated as controls. All groups were later challenged with a field strain of M. bovis. The results of the IFN-gamma response, serum antibody levels, M. bovis culture, TB lesion scores, and the expression of C3 and MUT genes were compared between these four groups. The results suggested that vaccination with heat-inactivated M. bovis or BCG protect wild boar from TB. These results also encouraged testing combinations of BCG and inactivated M. bovis to vaccinate wild boar against TB. Vaccine formulations using heat-inactivated M. bovis for TB control in wildlife would have the advantage of being environmentally safe and more stable under field conditions when compared to live BCG vaccines. The antibody response and MUT expression levels can help differentiating between vaccinated and infected wild boar and as correlates of protective response in vaccinated animals. These results suggest that vaccine studies in free-living wild boar are now possible to reveal the full potential of protecting against TB using oral M. bovis inactivated and BCG vaccines

Widespread environmental contamination with Mycobacterium tuberculosis complex revealed by a molecular detection protocol

Environmental contamination with Mycobacterium tuberculosis complex (MTC) has been considered crucial for bovine tuberculosis persistence in multi-host-pathogen systems. However, MTC contamination has been difficult to detect due to methodological issues. In an attempt to overcome this limitation we developed an improved protocol for the detection of MTC DNA. MTC DNA concentration was estimated by the Most Probable Number (MPN) method. Making use of this protocol we showed that MTC contamination is widespread in different types of environmental samples from the Iberian Peninsula, which supports indirect transmission as a contributing mechanism for the maintenance of bovine tuberculosis in this multi-host-pathogen system. The proportion of MTC DNA positive samples was higher in the bovine tuberculosis-infected than in presumed negative area (0.32 and 0.18, respectively). Detection varied with the type of environmental sample and was more frequent in sediment from dams and less frequent in water also from dams (0.22 and 0.05, respectively). The proportion of MTC-positive samples was significantly higher in spring (p<0.001), but MTC DNA concentration per sample was higher in autumn and lower in summer. The average MTC DNA concentration in positive samples was 0.82 MPN/g (CI95 0.70-0.98 MPN/g). We were further able to amplify a DNA sequence specific of Mycobacterium bovis/caprae in 4 environmental samples from the bTB-infected area

Performance of Proximity Loggers in Recording Intra- and Inter-Species Interactions: A Laboratory and Field-Based Validation Study

Knowledge of the way in which animals interact through social networks can help to address questions surrounding the ecological and evolutionary consequences of social organisation, and to understand and manage the spread of infectious diseases. Automated proximity loggers are increasingly being used to record interactions between animals, but the accuracy and reliability of the collected data remain largely un-assessed. Here we use laboratory and observational field data to assess the performance of these devices fitted to a herd of 32 beef cattle (Bos taurus) and nine groups of badgers (Meles meles, n  = 77) living in the surrounding woods. The distances at which loggers detected each other were found to decrease over time, potentially related to diminishing battery power that may be a function of temperature. Loggers were highly accurate in recording the identification of contacted conspecifics, but less reliable at determining contact duration. There was a tendency for extended interactions to be recorded as a series of shorter contacts. We show how data can be manipulated to correct this discrepancy and accurately reflect observed interaction patterns by combining records between any two loggers that occur within a 1 to 2 minute amalgamation window, and then removing any remaining 1 second records. We make universally applicable recommendations for the effective use of proximity loggers, to improve the validity of data arising from future studies

Formulation of a mmaA4 Gene Deletion Mutant of Mycobacterium bovis BCG in Cationic Liposomes Significantly Enhances Protection against Tuberculosis

A new vaccination strategy is urgently needed for improved control of the global tuberculosis (TB) epidemic. Using a mouse aerosol Mycobacterium tuberculosis challenge model, we investigated the protective efficacy of a mmaA4 gene deletion mutant of Mycobacterium bovis BCG (ΔmmaA4BCG) formulated in dimethyl dioctadecyl ammonium bromide (DDA) – D(+) trehalose 6,6 dibenenate (TDB) (DDA/TDB) adjuvant. In previous studies, deletion of the mmaA4 gene was shown to reduce the suppression of IL-12 production often seen after mycobacterial infections. While the non-adjuvanted ΔmmaA4BCG strain did not protect mice substantially better than conventional BCG against a tuberculous challenge in four protection experiments, the protective responses induced by the ΔmmaA4BCG vaccine formulated in DDA/TDB adjuvant was consistently increased relative to nonadjuvanted BCG controls. Furthermore, the ΔmmaA4BCG-DDA/TDB vaccine induced significantly higher frequencies of multifunctional (MFT) CD4 T cells expressing both IFNγ and TNFα (double positive) or IFNγ, TNFα and IL-2 (triple positive) than CD4 T cells derived from mice vaccinated with BCG. These MFT cells were characterized by having higher IFNγ and TNFα median fluorescence intensity (MFI) values than monofunctional CD4 T cells. Interestingly, both BCG/adjuvant and ΔmmaA4BCG/adjuvant formulations induced significantly higher frequencies of CD4 T cells expressing TNFα and IL-2 than nonadjuvanted BCG or ΔmmaA4BCG vaccines indicating that BCG/adjuvant mixtures may be more effective at inducing central memory T cells. Importantly, when either conventional BCG or the mutant were formulated in adjuvant and administered to SCID mice or immunocompromised mice depleted of IFNγ, significantly lower vaccine-derived mycobacterial CFU were detected relative to immunodeficient mice injected with non-adjuvanted BCG. Overall, these data suggest that immunization with the ΔmmaA4BCG/adjuvant formulation may be an effective, safe, and relatively inexpensive alternative to vaccination with conventional BCG

Predation Risk Shapes Social Networks in Fission-Fusion Populations

Predation risk is often associated with group formation in prey, but recent advances in methods for analysing the social structure of animal societies make it possible to quantify the effects of risk on the complex dynamics of spatial and temporal organisation. In this paper we use social network analysis to investigate the impact of variation in predation risk on the social structure of guppy shoals and the frequency and duration of shoal splitting (fission) and merging (fusion) events. Our analyses revealed that variation in the level of predation risk was associated with divergent social dynamics, with fish in high-risk populations displaying a greater number of associations with overall greater strength and connectedness than those from low-risk sites. Temporal patterns of organisation also differed according to predation risk, with fission events more likely to occur over two short time periods (5 minutes and 20 minutes) in low-predation fish and over longer time scales (>1.5 hours) in high-predation fish. Our findings suggest that predation risk influences the fine-scale social structure of prey populations and that the temporal aspects of organisation play a key role in defining social systems

Universal Plant DNA Barcode Loci May Not Work in Complex Groups: A Case Study with Indian Berberis Species

BACKGROUND: The concept of DNA barcoding for species identification has gained considerable momentum in animals because of fairly successful species identification using cytochrome oxidase I (COI). In plants, matK and rbcL have been proposed as standard barcodes. However, barcoding in complex genera is a challenging task. METHODOLOGY AND PRINCIPAL FINDINGS: We investigated the species discriminatory power of four reportedly most promising plant DNA barcoding loci (one from nuclear genome--ITS, and three from plastid genome--trnH-psbA, rbcL and matK) in species of Indian Berberis L. (Berberidaceae) and two other genera, Ficus L. (Moraceae) and Gossypium L. (Malvaceae). Berberis species were delineated using morphological characters. These characters resulted in a well resolved species tree. Applying both nucleotide distance and nucleotide character-based approaches, we found that none of the loci, either singly or in combinations, could discriminate the species of Berberis. ITS resolved all the tested species of Ficus and Gossypium and trnH-psbA resolved 82% of the tested species in Ficus. The highly regarded matK and rbcL could not resolve all the species. Finally, we employed amplified fragment length polymorphism test in species of Berberis to determine their relationships. Using ten primer pair combinations in AFLP, the data demonstrated incomplete species resolution. Further, AFLP analysis showed that there was a tendency of the Berberis accessions to cluster according to their geographic origin rather than species affiliation. CONCLUSIONS/SIGNIFICANCE: We reconfirm the earlier reports that the concept of universal barcode in plants may not work in a number of genera. Our results also suggest that the matK and rbcL, recommended as universal barcode loci for plants, may not work in all the genera of land plants. Morphological, geographical and molecular data analyses of Indian species of Berberis suggest probable reticulate evolution and thus barcode markers may not work in this case

Culling-Induced Changes in Badger (Meles meles) Behaviour, Social Organisation and the Epidemiology of Bovine Tuberculosis

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

The influence of refuge sharing on social behaviour in the lizard Tiliqua rugosa

Refuge sharing by otherwise solitary individuals during periods of inactivity is an integral part of social behaviour and has been suggested to be the precursor to more complex social behaviour. We compared social association patterns of active versus inactive sheltering individuals in the social Australian sleepy lizard, Tiliqua rugosa, to empirically test the hypothesis that refuge sharing facilitates social associations while individuals are active. We fitted 18 neighbouring lizards with Global Positioning System (GPS) recorders to continuously monitor social associations among all individuals, based on location records taken every 10 min for 3 months. Based on these spatial data, we constructed three weighted, undirected social networks. Two networks were based on empirical association data (one for active and one for inactive lizards in their refuges), and a third null model network was based on hypothetical random refuge sharing. We found patterns opposite to the predictions of our hypothesis. Most importantly, association strength was higher in active than in inactive sheltering lizards. That is, individual lizards were more likely to associate with other lizards while active than while inactive and in shelters. Thus, refuge sharing did not lead to increased frequencies of social associations while lizards were active, and we did not find any evidence that refuge sharing was a precursor to sleepy lizard social behaviour. Our study of an unusually social reptile provides both quantitative data on the relationship between refuge sharing and social associations during periods of activity and further insights into the evolution of social behaviour in vertebrates