Epidemiology Of Bovine Tuberculosis Research Articles

The challenge of estimating wildlife populations at scale: the case of the European badger (Meles meles) in Ireland

Estimating population size in space and time is essential for applied ecology and wildlife management purposes; however, making accurate and precise estimates at large scales is highly challenging. An example is the European badger (Meles meles), a widespread and abundant mammal in Ireland. Due to their role in the epidemiology of bovine tuberculosis, the species has been culled in agriculturally dominant landscapes with the intention of reducing spillback infection to local cattle populations. Despite several studies using different approaches having estimated badger populations at different time points and scales, there remains considerable uncertainty regarding the current population and its future trajectory. To explore this uncertainty, we use published data and expert opinion to estimate a snapshot of probable badger population size using a Monte Carlo approach, incorporating variation in three key components: social group numbers, group size, and culling efficacy. Using this approach, we estimate what the badger population in Ireland would be with/without culling, assuming a steady-state population at carrying capacity, and discuss the limitations of our current understanding. The mean estimate for the badger population size was 63,188 (5–95th percentile, 48,037–79,315). Population estimates were sensitive to the assumption of mean group size across landscape type. Assuming a cessation of culling (in favour of vaccination, for example) in agricultural areas, the mean estimated population size was 92,096 (5–95th percentile, 67,188–118,881). Despite significant research being conducted on badgers, estimates on population size at a national level in Ireland are only approximate, which is reflected in the large uncertainty in the estimates from this study and inconsistencies between recording of data parameters in previous studies. Focusing on carefully estimating group size, factors impacting its variation, in addition to understanding the dynamics of repopulation post-culling, could be a fruitful component to concentrate on to improve the precision of future estimates.

Whole Genome Sequence Analysis of Mycobacterium bovis Cattle Isolates, Algeria.

Mycobacterium bovis (M. bovis), a Mycobacterium tuberculosis complex species responsible for tuberculosis in cattle and zoonotic tuberculosis in humans, is present in Algeria. In Algeria however, the M. bovis population structure is unknown, limiting understanding of the sources and transmission of bovine tuberculosis. In this study, we identified the whole genome sequence (WGS) of 13 M. bovis strains isolated from animals exhibiting lesions compatible with tuberculosis, which were slaughtered and inspected in five slaughterhouses in Algeria. We found that six isolates were grouped together with reference clinical strains of M. bovis genotype-Unknown2. One isolate was related to M. bovis genotype-Unknown7, one isolate was related to M. bovis genotype-Unknown4, three isolates belonged to M. bovis genotype-Europe 2 and there was one new clone for two M. bovis isolates. Two isolates from Blida exhibited no pairwise differences in single nucleotide polymorphisms. None of these 13 isolates were closely related to four zoonotic M. bovis isolates previously characterized in Algeria. In Algeria, the epidemiology of bovine tuberculosis in cattle is partly driven by cross border movements of animals and animal products.

Epidemiology of Bovine Tuberculosis and Its Zoonotic Implication in Addis Ababa Milkshed, Central Ethiopia

Bovine tuberculosis (bTB) continues to be one of the most widely distributed chronic infectious diseases of zoonotic importance, which causes a significant economic loss in animal production. A cross-sectional study was conducted to estimate the prevalence of bTB and its associated risk factors and type the Mycobacterium bovis isolated in central Ethiopia. A total of 65 dairy farms and 654 cattle were tested for bTB using a single intradermal comparative cervical tuberculin (SICCT) test. Data on farm management, animal-related characteristics, and the owner's knowledge of the zoonotic importance of bTB were collected using a structured questionnaire. In addition, a total of 16 animals from different farms were identified for postmortem examination. Lowenstein Jensen (LJ) culture was also conducted, and spoligotyping was used to type the M. bovis strains isolated. Chi-square test and logistic regression models were used to analyze the herd- and animal-level risk factors. Herd- and animal-level prevalence rates of bTB were 58.5% (95% CI: 46.2%−69.2%) and 39.3% (95% CI: 35.5%−43.5%), respectively. At the herd level, poor farm management was the predictor for bTB positivity (p < 0.05). Animal breed, poor BCS, farm type, and poor farm management conditions were significant predictors of bTB positivity (p < 0.05) at an individual animal level. All animals identified for postmortem examination were found to have gross TB-like lesions. A total of 14 M. bovis strains were identified from 12 animals that were positive for LJ culture. The strain with the largest number of clusters (five isolates) was SB1176, followed by SB0134 (three isolates), SB0192 (two isolates), and SB2233 (two isolates), and two new strains, each consisting of only one isolate. The majority (58.5%) of the respondents did not know the zoonotic importance of bTB. The result of this study showed a high prevalence of bTB in the Addis Ababa milkshed and a low level of consciousness of the owners on its transmission to humans. Therefore, the launching of acceptable control measures of bTB and the creation of public awareness about its zoonotic transmission and prevention measures are required.

Characterization of potential superspreader farms for bovine tuberculosis: A review.

BackgroundVariation in host attributes that influence their contact rates and infectiousness can lead some individuals to make disproportionate contributions to the spread of infections. Understanding the roles of such ‘superspreaders’ can be crucial in deciding where to direct disease surveillance and controls to greatest effect. In the epidemiology of bovine tuberculosis (bTB) in Great Britain, it has been suggested that a minority of cattle farms or herds might make disproportionate contributions to the spread of Mycobacterium bovis, and hence might be considered ‘superspreader farms’.Objectives and MethodsWe review the literature to identify the characteristics of farms that have the potential to contribute to exceptional values in the three main components of the farm reproductive number ‐ Rf: contact rate, infectiousness and duration of infectiousness, and therefore might characterize potential superspreader farms for bovine tuberculosis in Great Britain.ResultsFarms exhibit marked heterogeneity in contact rates arising from between‐farm trading of cattle. A minority of farms act as trading hubs that greatly augment connections within cattle trading networks. Herd infectiousness might be increased by high within‐herd transmission or the presence of supershedding individuals, or infectiousness might be prolonged due to undetected infections or by repeated local transmission, via wildlife or fomites.ConclusionsTargeting control methods on putative superspreader farms might yield disproportionate benefits in controlling endemic bovine tuberculosis in Great Britain. However, real‐time identification of any such farms, and integration of controls with industry practices, present analytical, operational and policy challenges.

No energetic cost of tuberculosis infection in European badgers (Meles meles).

Energy availability and energy use directly influence an organism's life history, fitness and ecological function. In wild animals, abiotic factors such as ambient temperature, season and rainfall, and biotic factors such as body mass, age, social group size and disease status, all potentially influence energy balance. Relatively few studies have examined the effects of disease on the energy expenditure of wild animals. Such studies could further our understanding of factors influencing the transmission of zoonotic diseases. The European badger (Meles meles) is a medium-sized carnivore that occurs in mixed-sex, familial groups across much of its range. In the UK, they are a protected species but are also involved in the epidemiology of bovine tuberculosis (TB) in cattle. We measured the daily energy expenditure (DEE) and resting metabolic rate (RMR) of wild badgers and related this to their TB infection status and a range of other interacting factors including season, group size, disease status, sex, age, body mass and body fat. Individuals were larger and fatter when they were older, and fatter during the winter. Males were also heavier than females during the summer. In addition, individuals from smaller groups that were exposed to TB tended to have lower body mass. There were no direct effects of disease status on DEE or RMR; however, there was a significant interaction whereby DEE increased with body mass in small groups but decreased with body mass in large groups. Results are consistent with the costs of TB infection being met by compensatory mechanisms enabling badgers to survive for extended periods without exhibiting measurable energetic consequences.

To be or not to be (confirmed through bacteriology): spatial epidemiology of bovine tuberculosis in a low prevalence region in Spain

To be or not to be (confirmed through bacteriology): spatial epidemiology of bovine tuberculosis in a low prevalence region in Spain

Mycobacterium bovis Infection of Red Fox, France

Mycobacterium bovis infection in wild red foxes was found in southern France, where livestock and other wildlife species are infected. Foxes frequently interact with cattle but have been underestimated as a reservoir of M. bovis. Our results suggest a possible role of the red fox in the epidemiology of bovine tuberculosis.

Transmission of tuberculosis caused by Mycobacterium caprae between dairy sheep and goats

Increasing number of caprine tuberculosis (TB) reports grant the consideration of this zoonosis as an emerging disease that can play a role in the epidemiology of bovine TB in endemic areas. An outbreak of TB was detected in a caprine/ovine dairy mixed herd. Tuberculin skin test positive goats and ewes were euthanized and subsequent postmortem investigations were performed. Mycobacterium caprae (spoligotype profile SB0157) was isolated from tuberculous lesions detected in both sheep and goats. Our findings evidenced the direct transmission of the infection between both species elucidating that not only goats but also sheep may act as domestic reservoirs of TB compromising the eradication of TB in cattle. The results have implications for animal TB epidemiology and public health risk management.

Modelling the role of multi-transmission routes in the epidemiology of bovine tuberculosis in cattle and buffalo populations

A mathematical model that describes the transmission dynamics of bovine tuberculosis (BTB) in both buffalo and cattle populations is proposed. The model incorporates cross-infection and contaminated environment transmission routes. A full analysis of the model is undertaken. The reproduction number of the entire model is comprised of cross-infection and contaminated parameters. This underscores the importance of including both cross-infection and contaminated environment transmission routes. Crucially our simulations suggest that the disease has a more devastating effect on cattle populations than on buffalo populations when all transmission routes are involved. This has important implications for agriculture and tourism.

An outbreak of bovine tuberculosis in a fallow deer herd (Dama dama) in Sicily

Wild ruminants have an important role in the epidemiology of bovine tuberculosis (bTB). This study describes an outbreak of bovine tuberculosis occurring in a fallow deer herd in Sicily. In 2012 a Sicilian herd of 47 animals was referred for cachexia. Pathological examination of 2 dead animals revealed disseminated granulomas predominantly involving the skin and subcutaneous tissues. Tissue samples were submitted for histological analysis, bacteriological culture, and biomolecular assay. PCR analysis identified Mycobacterium strains. Genotyping by spoligotyping and MIRU-VNTR profiles identified Mycobacterium bovis spoligotype SB0120 in both animals. In 2014, bTB skin testing of 28 fallow deer from the same group was positive in 4 and inconclusive in another 4. All 8 positive/inconclusive reactors were euthanized. Disseminated granulomatous lesions were noted in 6 of these animals, 3 of which (2 positive and 1 negative to skin tests) also presented cutaneous lesions. M. bovis spoligotype SB0120 was identified from all animals in which tuberculous-like lesions were observed, including 2 negative reactors. Many of the animals involved in this outbreak presented diffuse skin lesions, a potential route of transmission of M. bovis infection. Given the epidemiological role wildlife play in the maintenance of bTB infection and its potential risk for humans, a comprehensive monitoring plan for this zoonosis in wildlife species in Sicily is needed.

First approach to molecular epidemiology of bovine tuberculosis in Colombia

ABSTRACT Objective. To investigate the presence of Mycobacterium bovis and other Mycobacterium species in samples of cattle and buffalo in Colombia, to start the molecular characterization of M. bovis in the country. Material and methods. 492 samples were collected from herds identified with the presence of infected animals through the PPD, by the Group of Bovine Tuberculosis ICA Colombian Agricultural Institute in eight departments of Colombia. Lymph nodes of head, thorax and abdomen, gross lesions of tissues with tuberculosis, nasal swabs, milk, blood and fresh cheeses were included. Samples were subjected to detection of Mycobacterium bovis and other mycobacteria by conventional microbiological analysis and PCR-6110 and spoligotyping molecular assays. Results. In the samples analyzed especially in lymph nodes, Mycobacterium bovis was demonstrated with genotypes reported and not previously reported in the world, as well as M. tuberculosis in Antioquia, Cundinamarca, Boyacá and Magdalena departments. Conclusions. In Colombia there are at least 7 genotypes of M. bovis that are infected and sick cattle and buffalo from four different departments becoming serious threat to public health.RESUMEN Objetivo. Investigar la presencia de Mycobacterium bovis y otras especies de Mycobacterium en muestras de ganado bovino y búfalino en Colombia e iniciar la caracterización molecular de M. bovis en el país. Materiales y métodos. 492 muestras fueron recogidas de hatos identificados con presencia de animales infectados a través de la prueba de PPD, por el Grupo de Tuberculosis Bovina del Instituto Colombiano Agropecuario ICA en ocho departamentos de Colombia. Se incluyeron ganglios linfáticos de cabeza, tórax y abdomen, tejidos con lesiones macroscópicas de tuberculosis, hisopos nasales, leche, sangre y quesos frescos. Las muestras se sometieron a investigación de Mycobacterium bovis y otras micobacterias mediante el análisis microbiológico convencional y pruebas moleculares de PCR-IS6110 y spoligotyping. Resultados. En las muestras analizadas especialmente en los ganglios linfáticos, se evidenció Mycobacterium bovis con genotipos reportados y no reportados previamente en el mundo, así como M. tuberculosis en los departamentos de Antioquia, Cundinamarca, Magdalena y Boyacá. Conclusiones. En Colombia existen al menos 7 genotipos de M. bovis que se encuentran infectando y enfermando a bovinos y bufalinos de cuatro diferentes departamentos del país constituyéndose en seria amenaza para la salud pública.

Molecular Epidemiology of Bovine Tuberculosis in Cattle and its Public Health Implications in Gambella Region, Ethiopia

A cross sectional study was conducted from December 2014 to May 2015 in Gambella town municipal abattoir and health centers to investigate the prevalence of bovine tuberculosis, isolation and molecular characterization of its causative agents, and to assess its public health implications in Gambella, Ethiopia. Postmortem examination, bacteriological culturing, RD deletion typing, and spoligotyping were used for investigation. The overall prevalence of bovine tuberculosis in cattle was 13.2% (66/500) on the basis of detailed postmortem examination. Statistical significant difference was observed in the prevalence of bovine tuberculosis among different body conditioned animals (χ2 = 39.105, P=0.000 and breeds (χ2 = 24.996, P=0.000). Molecular characterization of 11 mycobacterial isolates from human patients using RD9 deletion typing showed that all were M. tuberculosis , and further spoligotyping of the isolates revealed that SIT289, SIT134, SIT1634, SIT142 and one new strain (not found in the spoligotype databases). Of these M. tuberculosis strains identified, SIT 289 and SIT134 were found in cluster with 45.5% (5/11) cluster rate. Lineage of the human isolates indicated that 27.3% (3/11) were in Euro-American, and 9.1% (1/11) Indo-oceanic family in TB-insight database. Interestingly, one isolate from animal taken from mediastinal lymph node was confirmed to be M. tuberculosis using RD4 deletion typing and spoligotyping, in which the isolate was identified as SIT523 with Indo-oceanic lineage family. Awareness of cattle owners for bovine tuberculosis was found insufficient (22%), and the results also revealed the presence of potential risk factor for zoonotic transmission. In conclusion, isolation of M. tuberculosis in cattle, and occurrence of various strains of M. tuberculosis in the communities warrants further systematic investigation on the transmission of the disease in Gambella region of Ethiopia.

Isolation and Phylogenetic Characterization of Streptococcus halichoeri from a European Badger (Meles meles) with Pyogranulomatous Pleuropneumonia

Clinical and pathological studies in European badgers (Meles meles) are limited. Badgers play a significant role in the epidemiology of bovine tuberculosis (TB) in some countries and an accurate diagnosis is needed for this infection. However, the lesions of bovine TB are similar to those associated with other pathogens, making pathological diagnosis difficult. In the present study, Streptococcus halichoeri was isolated from a European badger with pyogranulomatous pleuropneumonia and suspected of having tuberculosis. TB and other pathogens able to induce similar lesions were ruled out. Comparative 16S rRNA and rpoB gene sequencing studies showed an identity of 99.51% and 98.28%, respectively, with S. halichoeri. This report represents the third description of this bacterium and the first in an animal species other than the grey seal (Halichoerus grypus). It also shows that S. halichoeri can be associated with a pathological process characterized by granulomatous inflammation and resembling tuberculosis.

English

A cross-sectional study was conducted at Butajira Municipality abattoir from December, 2009 to April 2010 to investigate the epidemiology of bovine tuberculosis (bTB) in Butajira, Southern Ethiopia. Postmortem examination, mycobacterial culturing and multiplex genus typing techniques were used. An overall prevalence of 9% (40/446) of the animals examined harbor gross tuberculous lesions up on detailed post-mortem examination. Statistically significant difference was observed in the prevalence of bTB between different age groups (χ2 = 11.441, p= 0.003) and body condition scoring (χ2 = 10.384, p = 0.006). Higher prevalence of bTB was observed in older animals and animals with poor body condition. Bacteriological culture of the 40 samples gave growth on 13 with 9 of them acid fast Bacilli (AFB) positive. Genus typing of the AFB positive isolates by multiplex polymerase chain reaction (m-PCR) revealed seven non-tuberculous mycobacterium (NTM) and 1 Mycobacterium tuberculosis complex (MTBC) isolates. Further characterization of the isolates at specific species and investigation of the disease is recommended for controlling it in livestock and safeguard public health. Key words: Abattoir, bovine tuberculosis, Butajira, multiplex genus typing, epidemiology, Ethiopia, postmortem examination, prevalence.

Multi-locus variable-number tandem repeat analysis (MLVA) reveals heterogeneity of Mycobacterium bovis strains and multiple genotype infections of cattle in Ethiopia

Bovine tuberculosis (BTB) remains a major threat to animal and human health, and obstructs international and inter-regional livestock trade in Ethiopia. Many aspects of epidemiology of BTB and its causative agent, Mycobacterium bovis (M. bovis) are not well known. Aims of the study were to elucidate molecular characteristics of M. bovis strains using MLVA typing method. Further aim was to determine infection pressure associated with occurrence of multiple genotypes in individual infected cattle. Data and samples were collected in the period July 2006–January 2007 in cattle slaughtered at five representative abattoirs across the country. Molecular investigation of the isolates was carried out using multilocus variable-number tandem-repeat analysis (MLVA) of 28 variable numbers of tandem repeat (VNTR) loci, and the results were compared to spoligotyping. This study is believed to contribute to the knowledge of molecular genetics and epidemiology of M. bovis in Ethiopia and elsewhere with similar BTB epidemic situation and livestock production settings. Four-hundred and six tissue samples from 337 carcasses revealing gross pathologic lesions compatible with BTB were collected from five abattoirs. Fifty-eight isolates obtained from cultured samples were subjected to region of difference (RD) analysis and MLVA typing. RD confirmed all isolates as being M. bovis. MLVA revealed a high heterogeneity of M. bovis (19 genotypes) and the discriminatory power of MLVA was higher than for spoligotyping (Hunter–Gaston Diversity Index (HGDI) 0.92 vs. 0.82). Adoption of the nine VNTR loci with ⩾3 alleles provided good differentiation between the isolates. However, differentiation was optimized when MLVA was combined with spoligotyping (HGDI=0.99). MLVA confirmed infections with multiple genotypes in 38.5% (10/26) of individual animals. In conclusion, the usefulness of MLVA for genotyping M. bovis in high prevalence settings was demonstrated. BTB in Ethiopia is caused by heterogeneous populations of M. bovis and individual carcasses were often infected with different genotypes, indicating a high infection pressure perhaps related to the absence of protective immunity conferred by infection.

Age-dependent patterns of bovine tuberculosis in cattle

Bovine tuberculosis (BTB) is an important livestock disease, seriously impacting cattle industries in both industrialised and pre-industrialised countries. Like TB in other mammals, infection is life long and, if undiagnosed, may progress to disease years after exposure. The risk of disease in humans is highly age-dependent, however in cattle, age-dependent risks have yet to be quantified, largely due to insufficient data and limited diagnostics. Here, we estimate age-specific reactor rates in Great Britain by combining herd-level testing data with spatial movement data from the Cattle Tracing System (CTS). Using a catalytic model, we find strong age dependencies in infection risk and that the probability of detecting infection increases with age. Between 2004 and 2009, infection incidence in cattle fluctuated around 1%. Age-specific incidence increased monotonically until 24–36 months, with cattle aged between 12 and 36 months experiencing the highest rates of infection. Beef and dairy cattle under 24 months experienced similar infection risks, however major differences occurred in older ages. The average reproductive number in cattle was greater than 1 for the years 2004–2009. These methods reveal a consistent pattern of BTB rates with age, across different population structures and testing patterns. The results provide practical insights into BTB epidemiology and control, suggesting that targeting a mass control programme at cattle between 12 and 36 months could be beneficial.

Impact of culling on relative abundance of the European badger (Meles meles) in Ireland

The European Badger (Meles meles) has been implicated in the epidemiology of bovine tuberculosis in cattle populations in the Republic of Ireland. Badger populations have been subject to a culling regime in areas with chronic histories of bTB cattle herd breakdowns. Removal data from 2004 to 2010 were used to model the impact of culling on populations in areas under capture. Additionally, changes in field signs of badger activity were used as an index of abundance to support, or otherwise, the outcomes of the removal models. Significant reductions in standardised badger captures over time were found across three large study areas (total area, 1,355 km2). Assuming that all inactive setts were vacant, an overall linear trend model suggested that badger captures had decreased by 78 % for setts with 6 years of repeated capturing operations. Given the uncertainty associated with the relationship between sett activity and badger presence, we repeated the linear modelling using two ‘what if’ scenarios. Assuming that individual badgers were missed on 10 % or 20 % of occasions at inactive setts, the estimated decline over 6 years is lowered to 71 % or 64 %, respectively. The decline profile consisted of a steep initial decrease in captures within the first 2 years, followed by a more gradual decrease thereafter. The number of active openings at setts (burrows) declined significantly in all three areas; but the magnitude of this decline varied significantly amongst study areas (41–82 %). There was a significant increase in the probability of setts becoming dormant with time. The removal programme was more intense (mean, 0.45 badgers culled km−2 year−1) than previous experimental badger removals in Ireland but some captures may be attributed to immigrant badgers as no attempt was made to limit inward dispersal from areas not under management. Results from this study suggest that significant reductions in badger density occurred in the areas where management had taken place. Since other non-culled badger populations in Northern Ireland and Britain exhibited stable population trends, we attribute the reduction in relative abundance to the culling regime. Further studies of the dynamics of this reduction are required to quantify how it is counteracted by immigration from populations outside of culled areas.

Histological and immunohistochemical characterisation of Mycobacterium bovis induced granulomas in naturally infected Fallow deer (Dama dama)

Mycobacterium bovis infections in fallow deer have been reported in different countries and play an important role in the epidemiology of bovine tuberculosis (bTB), together with other deer species. There is little knowledge of the pathogenesis of bTB in fallow deer. The aim of this study was to perform a histopathological characterisation of the granulomas induced by M. bovis in this species and the immunohistochemical distribution of different cell subsets (CD3+, CD79+, macrophages) and chemical mediators (iNOS, TNF-α, IFN-γ) in the different developmental stages of granulomas. Stage I/II granulomas showed a marked presence of macrophages (MAC387+) expressing high iNOS levels while stage III/IV granulomas showed a decrease in the number of these cells forming a rim surrounding the necrotic foci. This was correlated with the presence of IFN-γ expressing cell counts, much higher in stage I/II than in stage III/IV. The number of B cells increased alongside the developmental stage of the granuloma, and interestingly the expression of TNF-α was very low in all the stages. This characterisation of the lesions and the local immune response may be helpful as basic knowledge in the attempts to increase the vaccine efficacy as well as for disease severity evaluation and for the development of improved diagnostic tools. Immunohistochemical methods using several commercial antibodies in fallow deer tissues are described.

Preliminary study on the epidemiology of bovine tuberculosis in Jimma town and its surroundings, Southwestern Ethiopia

A cross-sectional study was conducted from October 2007 to April 2008 on 384 dairy cattle in Jimma Town and 1,102 adult cattle slaughtered at Jimma abattoir. The objective of the study was to generate preliminary epidemiological data on bovine TB both in dairy and beef cattle in Jimma and its area. Simple random sampling, single intradermal tuberculin (SIDT) and comparative intradermal tuberculin (CIDT) tests of dairy cattle and postmortem inspection of slaughter cattle were used. On the basis of CIDT test, herd and animal prevalence were found to be 48.6% (95% CI, 34.8-68.0) and 21.4% (95% CI, 17.3-25.5), respectively. In dairy herd, prevalence of bovine TB was significantly affected by herd size (c2 = 7.1; P< 0.05) and age (c2 =14.7; P<0.05). A prevalence of 5.4% (95% CI, 4.1-6.7) was recorded in cattle slaughtered at Jimma abattoir based on detailed postmortem examination. The occurrence of tuberculous lesions was variable in different tissues: 63.3% in the lungs and associated lymph nodes, 23.5% in the mesenteric lymph nodes and the remaining 13.2% in the lymph nodes of the head region. In conclusion, the result of the present study indicated the prevailing occurrence of bovine TB in the area and warrants for launching of control methods. Key words: Bovine tuberculosis, prevalence, risk factors, tuberculin tests, meat inspection, Jimma, Ethiopia.

Simulating the impact of badger culling on bovine tuberculosis in cattle

IT is now 15 years since the Krebs report on bovine tuberculosis (TB) in cattle and badgers highlighted the need for a rigorous scientific trial to quantify the role of...