Spread Of bTB Research Articles

Knowledge and Preventive Practices of Abattoir Workers toward Bovine Tuberculosis in Wolaita Zone, Southern Ethiopia.

Bovine tuberculosis (bTB) is a zoonotic bacterial disease of animals that causes substantial economic losses in underdeveloped countries such as Ethiopia. A cross-sectional study was conducted from May 2021 to August 2021 in the Wolaita zone, southern Ethiopia using a designed questionnaire to assess risk, perception, and protective behavior against bTB. For this purpose, a total of 250 randomly chosen meat handlers working at six main, purposively selected abattoirs were interviewed, and the data were analyzed using STATA v. 13 software. Of the total participants interviewed, 37.0% (57/152) of the respondents strongly agreed that contracting bTB would prevent them from coming to work, whereas 32.4% (44/136) of them stayed in bed for an extended period. Knowledge-based analysis revealed that butcher house men were more aware than abattoir workers about factors related to the spread of bTB from animals to humans (73.3%), that healthy-looking meat contains bTB-causing pathogens (67.5%), and that consumption of contaminated meat can be a source of infection in humans (65.6%). These findings revealed that abattoir and butcher house employees are at higher risk of bTB exposure and a lack of understanding about the nature and transmission of the infection. Thus, abattoir and butcher house workers should be encouraged to pursue regular medical follow-ups and should be provided with better personal protective equipment.

Prevalence and risk factors associated with bovine tuberculosis in the southern zone of Nasarawa State, north-central Nigeria

A cross-sectional study was conducted on 500 grazing cattle under a pastoral production system in the southern zone of Nasarawa state, North-Central Nigeria to determine the prevalence and risk factors associated with bovine tuberculosis using a Single intradermal Comparative Tuberculin Test (SCITT) from April 2019 to February 2020. The total number of animals with bTB was 46 (9.2%) and the results were significantly higher in older animals between 5-6years (OR: 7.4; CI: 1.54-35.4; P=0.000) and in those animals that were ≥ 7 years (OR: 5.7; CI: 1.24-25-9; P=0.00) old and likely at risk of having more bTB. Additionally, the prevalence was significantly higher in female animals (OR:3.7; CI:1.5-8.8; p=0.003), also a significant prevalence was observed as the herd size increased from 31-80 (OR:1.95; CI: 0.75-5.0; p=0.000) as well as from 81-171 (OR:5.5; CI: 2.14-14.4; p=0.000). Moreso, the prevalence was significant with the location of the animals, as areas with grazing reserves appeared to have more odds and more likely to have bTB: Awe (OR:9.6; C I:.2-4.4); Doma (OR:6.9; I:1.5-30.1; p= 0.01); Keana (OR:4.5; CI:0.96-21.6; p=0.01); Obi (OR:3.5; CI:0.7-17; p=0.01). The major risk factors for bovine tuberculosis in this study were sex, age, herd size, and location, contributing largely to the spread of bTB in the study area.

Estimating landscape spread of a low‐prevalence disease using multiple surveillance methods

Abstract Diseases occurring at low prevalence in free‐ranging wildlife can be difficult to study and predict at a landscape scale. This problem is compounded by imperfect pathogen detection. We used data from multiple surveillance methods to determine factors influencing spread of a low‐prevalence disease, bovine tuberculosis (bTB), among white‐tailed deer (Odocoileus virginianus) in a bTB endemic area over a 10‐year period. We fit dynamic occupancy models to predict spatial spread of bTB through a county in Michigan, USA, within the bTB endemic area, while accounting for imperfect detection and a suite of ecological processes potentially driving bTB spread. Detection by all surveillance methods was low overall (posterior mean detection probabilities 0.01–0.03). Probability of bTB occurrence was 1.46 times as likely in the historical centre of the outbreak compared to outside. Deer density had a weakly positive effect on bTB spread. The probability of a site being newly infected with bTB annually was low (posterior mean colonization probabilities 0.08–0.27), while the probability of persistence after initial infection was high (posterior mean persistence probability 0.67). Synthesis and applications: We used three surveillance methods to estimate probability of presence and spread of a low‐prevalence pathogen at a landscape scale under incomplete sampling coverage. Our methods are relevant for determining spatial risk of any wildlife disease that is monitored using multiple methods of surveillance, which is important for prioritization of management actions.

Mycobacterium bovis and its impact on human and animal tuberculosis.

Graphical abstract Mycobacterium bovis is a slow-growing (16–20 h generation time), Gram-positive and acid-fast bacterium member of the Mycobacterium tuberculosis complex pathogen group (MTBC). They are characterized by a complex, protective cell wall containing mycolic acids. The MTBCs are the causative agents of tuberculosis (TB). Following initial infection, subsequent pathological changes, and the progress of infection depend on the interplay between host defence mechanisms and mycobacterial virulence factors and the balance between the immunologic protective responses and the damaging inflammatory processes. Progression of the disease is characterized by the formation of typical caseous tuberculous granuloma (inflammatory mononuclear cell aggregates) because of the host's immune response to infection. The transmission and epidemiology of Mycobacterium bovis are complex and vary depending on the situation and ecosystem. In the UK, the spread of BTB in the UK cattle herd can occur by transmitting the disease from cattle to cattle and between badgers but also between badgers and cattle. The disease is thought to be primarily a respiratory disease with spread between individuals through mechanisms such as coughing or transfer of bacteria in respiratory secretions. It is also thought that environmental contamination may also lead to some transmission. The protective cell wall of the organism is believed to allow the organism to survive outside an animal host, which can then transfer to new hosts following subsequent environmental exposure. In some situations, ingestion of pathogens in food can lead to infection. The relative contribution of these routes and precise transmission mechanisms needs to be better understood.

Sero-epidemiology of bovine tuberculosis in dairy cattle in Chattogram, Bangladesh

Mycobacterium bovis-caused bovine tuberculosis (bTB) is a global public health concern and commercially significant zoonotic disease. Many wild and domesticated animals, including cattle, are susceptible to this fatal disease and play an important role in cross-species transmission. To gain a better understanding of bTB in dairy cattle, a bTB serological study is also necessary in order to identify efficient bTB control strategies in Bangladesh. In Bangladesh, however, seroepidemiological research is either non-existent or limited (particularly Chattogram). To determine the seroprevalence of bTB and related possible risk factors in dairy cattle, a serological cross-sectional study was conducted (both animal and farm level). We estimated the seroprevalence of bTB was 7.5%(N=442) in this investigation, which also identified one animal-level and two farm-level possible risk factors. Individual animal risk factors included cattle source (own stock: OR=3.4, 95% CI: 1.4-8.1, p=0.006), and farm risk factors included population size (Larger: OR= 26.2, 95% CI: 2.2-319.1, p=0.010) and stocking density (Low and moderate: OR=19.6, 95%CI: 1.5-261.5, p=0.024). In the face-in housing system, there was also a higher risk of bTB seropositivity (OR=4.5). The research's key findings are thoroughly explored, and the findings will aid in the prevention and control of bTB in Bangladesh. In addition, early detection of positive cases, as well as their prompt removal and good farm management practices, can assist in preventing the spread of bTB to new human or bovine hosts. In underdeveloped nations like Bangladesh, a coordinated effort with local public health officials is critical for implementing an efficient TB control program.

Mapping and Filiation of Bovine Tuberculosis Outbreaks in Türkiye (2017-2021)

Since the beginning of the XXI. century, it has been seen that bovine tuberculosis (bTB) disease in Türkiye has both increased in the number of outbreaks and gradually spread throughout the country. This study aims to map the spatial distribution of bTB between 2017 and 2021 at the scale of outbreak premises. Besides, the basic data of the research, which includes the results of the filiation studies carried out in the outbreak premises, were taken from the veterinary information system. The inclusion of the geographical coordinates of each premises with a bTB outbreak in the system has enabled point mapping of the data throughout Türkiye by using geographical information systems. As a result, the spatial distribution of the number of bTB outbreaks both in Türkiye and in the province of Erzurum, annual and five-years temporal distribution patterns, filiation graphs of the disease, and animal movements in the outbreak premises were revealed. Although the number of bTB outbreaks varies according to years, thanks to the fact that the spatial scale in the data is at the premises level, the clustering areas in the country are determined in much more detail than the distribution maps according to the provinces. Two points provide as a concise summary of the findings. The first is to explain the spatial spread of bTB across the country; secondly, it is expected to guide decision-makers to identify target intervention areas in the fight against the disease and to determine the national fight strategy.

Analysis of a multi-type resurgence of Mycobacterium bovis in cattle and badgers in Southwest France, 2007-2019

Although control measures to tackle bovine tuberculosis (bTB) in cattle have been successful in many parts of Europe, this disease has not been eradicated in areas where Mycobacterium bovis circulates in multi-host systems. Here we analyzed the resurgence of 11 M. bovis genotypes (defined based on spoligotyping and MIRU-VNTR) detected in 141 farms between 2007 and 2019, in an area of Southwestern France where wildlife infection was also detected from 2012 in 65 badgers. We used a spatially-explicit model to reconstruct the simultaneous diffusion of the 11 genotypes in cattle farms and badger populations. Effective reproduction number R was estimated to be 1.34 in 2007–2011 indicating a self-sustained M. bovis transmission by a maintenance community although within-species Rs were both < 1, indicating that neither cattle nor badger populations acted as separate reservoir hosts. From 2012, control measures were implemented, and we observed a decrease of R below 1. Spatial contrasts of the basic reproduction ratio suggested that local field conditions may favor (or penalize) local spread of bTB upon introduction into a new farm. Calculation of generation time distributions showed that the spread of M. bovis has been more rapid from cattle farms (0.5–0.7 year) than from badger groups (1.3–2.4 years). Although eradication of bTB appears possible in the study area (since R < 1), the model suggests it is a long-term prospect, because of the prolonged persistence of infection in badger groups (2.9–5.7 years). Supplementary tools and efforts to better control bTB infection in badgers (including vaccination for instance) appear necessary.

Predicting bovine tuberculosis status of dairy cows from mid-infrared spectral data of milk using deep learning

Bovine tuberculosis (bTB) is a zoonotic disease in cattle that is transmissible to humans, distributed worldwide, and considered endemic throughout much of England and Wales. Mid-infrared (MIR) analysis of milk is used routinely to predict fat and protein concentration, and is also a robust predictor of several other economically important traits including individual fatty acids and body energy. This study predicted bTB status of UK dairy cows using their MIR spectral profiles collected as part of routine milk recording. Bovine tuberculosis data were collected as part of the national bTB testing program for Scotland, England, and Wales; these data provided information from over 40,500 bTB herd breakdowns. Corresponding individual cow life-history data were also available and provided information on births, movements, and deaths of all cows in the study. Data relating to single intradermal comparative cervical tuberculin (SICCT) skin-test results, culture, slaughter status, and presence of lesions were combined to create a binary bTB phenotype labeled 0 to represent nonresponders (i.e., healthy cows) and 1 to represent responders (i.e., bTB-affected cows). Contemporaneous individual milk MIR spectral data were collected as part of monthly routine milk recording and matched to bTB status of individual animals on the single intradermal comparative cervical tuberculin test date (±15 d). Deep learning, a sub-branch of machine learning, was used to train artificial neural networks and develop a prediction pipeline for subsequent use in national herds as part of routine milk recording. Spectra were first converted to 53 × 20-pixel PNG images, then used to train a deep convolutional neural network. Deep convolutional neural networks resulted in a bTB prediction accuracy (i.e., the number of correct predictions divided by the total number of predictions) of 71% after training for 278 epochs. This was accompanied by both a low validation loss (0.71) and moderate sensitivity and specificity (0.79 and 0.65, respectively). To balance data in each class, additional training data were synthesized using the synthetic minority over sampling technique. Accuracy was further increased to 95% (after 295 epochs), with corresponding validation loss minimized (0.26), when synthesized data were included during training of the network. Sensitivity and specificity also saw a 1.22- and 1.45-fold increase to 0.96 and 0.94, respectively, when synthesized data were included during training. We believe this study to be the first of its kind to predict bTB status from milk MIR spectral data. We also believe it to be the first study to use milk MIR spectral data to predict a disease phenotype, and posit that the automated prediction of bTB status at routine milk recording could provide farmers with a robust tool that enables them to make early management decisions on potential reactor cows, and thus help slow the spread of bTB.

Challenges for controlling bovine tuberculosis in South Africa.

All effects taken together, bovine tuberculosis (bTB) has a long-term detrimental effect on bovine herds and many wildlife species in South Africa. The disease is not only found in domestic cattle but also in African buffaloes and has to date been diagnosed in 21 wildlife species, including several rare and endangered species, thus having a potentially serious effect on conservation and biodiversity. In cattle, bTB is mostly characterised by sporadic outbreaks, but bovine herds chronically infected with the clinical disease are not uncommon. Presently, the recognised bTB control strategy in South Africa is based on ‘test and slaughter’, using the intradermal tuberculin test, followed by the slaughter of animals that have tested positive. Affected herds are placed under veterinary quarantine with movement restrictions until the outbreak is eradicated; this can take several years or last indefinitely if the outbreak cannot be eradicated. The same measures apply to infected buffalo populations, often with no prospect of ever being eradicated. This strategy is neither practical nor viable in the context of a communal farming system and becomes unethical when dealing with valuable wildlife reservoir hosts. Transmission of bTB between wildlife and cattle has been demonstrated and emphasises the need for an effective, affordable and culturally acceptable control strategy to curb the spread of bTB in South Africa. In countries with similar challenges, vaccination has been used and found to be promising for treating wild and domestic reservoir species and may hence be of value as a complementary tool for bTB control in South Africa.

The spread of bovine tuberculosis in Canadian shared pastures: Data, model, and simulations.

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a chronic disease typical of cattle. Nonetheless, it can affect many mammals including humans, making it one of the most widespread zoonotic diseases worldwide. In industrialized countries, the main pathways of introduction of bTB into a herd are animal trade and contact with infected wildlife. In addition, for slow-spreading diseases with a long latent period such as bTB, shared seasonal pastures might be a between-herd transmission pathway, indeed farmers might unknowingly send infected animals to the pasture, since clinical signs are rarely evident in early infection. In this study, we developed a dynamic stochastic model to represent the spread of bTB in pastures. This was tailored to Canadian cow-calf herds, as we calibrated the model with data sourced from a recent bTB outbreak in Western Canada. We built a model for a herd with seasonal management, characterized by its partition into a group staying in the main facility and the remaining group(s) moving to summer pastures. We used this model to estimate the time of the first introduction of bTB into the herd. Furthermore, we expanded the model to include herds categorized as high-risk contacts with the index herd, in order to estimate the potential for disease spread on shared pastures. Finally, we explored two control scenarios to be applied to high-risk farms after the outbreak detection. Our results showed that the first introduction likely happened 3 to 5years prior to the detection of the index herd, and the probability of bTB spreading in pastures was low, but not negligible. Nevertheless, the surveillance system currently in place was effective to detect potential outbreaks.

Investigation of intra-herd spread of Mycobacterium caprae in cattle by generation and use of a whole-genome sequence.

Single nucleotide polymorphisms (SNPs) calculated from whole genome sequencing (WGS) are ideally suited to study evolutionary relationships of pathogens and their epidemiology. Mycobacterium caprae infections have been documented frequently in cattle and red deer along the Bavarian and Austrian Alps during the last decade. However, little is still known about the transmission within cattle holdings and possible alterations of the genomes of M. caprae during such events. The aim of this study was to study the molecular epidemiology of bovine tuberculosis (bTB) in selected herds based on isolate-specific genome-wide SNPs and to perform a phylogenetic network analysis. In total, 61M. caprae isolates were collected originating from eight cattle farms over a period of twelve years between 2004 and 2015. Analysis of their sequence data revealed that the M. caprae isolates of an affected farm differ at all in a few SNPs. In contrast, many more SNPs were found when comparing the M. caprae genomes originating from different herds. The results demonstrated that the spread of bTB in the affected farms occurred by direct transmission between the members of each herd rather than between herds and a M. caprae introduction in farms after contact events e. g. on summer pastures can readily be traced by WGS analysis. Furthermore, we assembled a nearly complete whole genome sequence of M. caprae derived from several cattle isolates originating from bTB cases in the Bavarian Alpine region.

Wildlife Interactions on Baited Places and Waterholes in a French Area Infected by Bovine Tuberculosis.

Interactions among wildlife species are major drivers for the transmission of multi-host pathogens, such as Mycobacterium bovis, which also affect livestock. Although France is officially free from bovine tuberculosis (bTB), some areas are still harboring infection in cattle and wildlife. We aimed at characterizing the visits of susceptible wild species (badger, red deer, and wild boar) at baited places and waterholes, considered as possible hotspots for contacts. We described the visits in terms of frequency, duration, and number of individuals and studied the influence of the season. Then, we estimated the frequency of intraspecies and interspecies interactions occurring at baited places and waterholes which may lead to bTB transmission, including direct and indirect contacts through the soil or water. We used camera traps placed on baited places and waterholes on 13 locations monitored during 21 months. The number of visits, their duration, and the number of individuals per visit were analyzed by generalized linear mixed models for each targeted species. The frequency of the interspecies and intraspecies interactions was also analyzed separately. The season, the type of site (baited place or waterhole), and the location were the explanatory variables. Badgers’ visits and interactions were more frequent than for other species (mean: 0.60 visit/day and 5.42 interactions/day) especially on baited places. Red deer only visited waterholes. Wild boars visited most often baited places in spring–summer and waterholes in autumn–winter. They came in higher number than other species, especially on baited places. Direct interactions were uncommon. The most frequent interspecies interactions occurred between red deer and wild boar (mean: 4.02 interactions/day). Baited places and waterholes are important interfaces between the different wild species involved in the bTB multi-host system in this area. They can thus promote intraspecies and interspecies bTB transmission. Baiting ban should be carried on and management of waterholes should be considered as tool to limit the spread of bTB in wildlife.

Spoligotype diversity and 5-year trends of bovine tuberculosis in Extremadura, southern Spain.

Bovine tuberculosis (bTB) causes significant losses to farming economies worldwide. A better understanding on the epidemiology of this disease and the role that the different hosts develop in the maintenance and spread of bTB is vital to control this zoonotic disease. This study reports the spoligotype diversity and temporal evolution of Mycobacterium tuberculosis Complex (MTBC) isolates obtained from Extremadura (southern Spain). Genotyping data of Mycobacterium bovis (n = 2102) and Mycobacterium caprae (n = 96) isolates from cattle and wildlife species, collected between 2008 and 2012, were used in this study. The isolates resulted clustered into 88 spoligotypes which varied largely in frequency and occurrence in the three hosts. The 20 most frequent patterns represented 91.99% of the isolates, the spoligotype SB0121 being the clearly predominant and most widely dispersed geographically. The major variety of the spoligotype patterns (78 out of 88) was isolated from the cattle, in fact 50 (56.83%) of the patterns were found only in this species. Within the spoligotypes shared between the cattle and wildlife species, 17 patterns (1747 isolates) were shared with wild boar and Iberian red deer, 10 patterns (308 isolates) were exclusively shared with wild boar, and only one pattern (two isolates) was shared exclusively with Iberian red deer. The significant number of spoligotypes shared between the three hosts (79.49%) highlights the components of the multi-host system that allows the bTB maintenance in our study area. The greater percentage of isolates shared by the wild boar and cattle (93.50%) supports the role of wild boar as main maintenance host for bTB in cattle. These results could be extrapolated to areas with a similar epidemiological scenario and could be helpful for other countries where wild reservoirs represent a handicap for the successful eradication of bTB from livestock.

Farming on the edge: farmer attitudes to bovine tuberculosis in newly endemic areas

Defra's recent strategy to eradicate bovine tuberculosis (bTB) establishes three spatial zones: high-risk areas (HRAs) and low-risk areas, and an area referred to as ‘the edge’, which marks the areas...

Badger Vaccination: Dimensions of Trust and Confidence in the Governance of Animal Disease

This paper examines farmers' trust in badger vaccination as a method of preventing the spread of bovine tuberculosis (bTB) between wildlife (specifically, badgers) and cattle in England. The spread of bTB has economic and social implications for farmers, but previous research has found that lack of trust in government is a key factor in farmers' failure to adopt new preventative biosecurity practices. In these and other studies, however, the conceptual dimensions of trust are frequently loosely defined, meaning that it is unclear how trust, along with other factors, is related to the acceptance of new biosecurity practices such as vaccination. Drawing on findings from a telephone survey of 339 farmers and in-depth interviews with a subsample of 65, the paper explores attitudes towards, and levels of acceptance of, badger vaccination amongst farmers across five study areas with varying levels of bTB disease. Results reveal low levels both of trust in government to manage bTB and confidence in badger vaccination. Principal components analysis identifies three specific dimensions of trust which, along with farmers' perceived self-efficacy, the perceived threat of disease, and faith in others to manage disease, are all significantly related to the acceptability of badger vaccination.

Characteristics of white-tailed deer visits to cattle farms: implications for disease transmission at the wildlife–livestock interface

Bovine tuberculosis (bTB) is endemic in free- ranging white-tailed deer (Odocoileus virginianus )i n MI, USA. Currently, the rates of farm visitation by deer and co- use of forage resources by cattle and deer are poorly under- stood. To evaluate the extent deer and livestock may share forage resources, we investigated farm, yard, and cattle-use area visitation by white-tailed deer and compared visitation with common livestock management practices. We fitted 25 female white-tailed deer near the bTB-infected zone in Michigan's Lower Peninsula with global positioning system collars. Livestock management practices associated with farm visitation included presence of confined feeding pastures, num- ber of cattle water sources, and the number of cattle pastures. Fewer farm visits occurred at night than during the day. A higher proportion of nighttime visits occurred between mid- night and sunrise. Visitation to yards and cattle-use areas were similar: a higher proportion of visits occurred at night, and a higher proportion of nighttime visits occurred between mid- night and sunrise. Multiple visits during the same day were common. Visitation increased through spring and peaked dur- ing the fawning season. Results suggest that mitigation and control efforts to guard against potential transmission of bTB should include the season and time of day during which deer visitation occurs. Furthermore, specific livestock management practices may contribute to farm visitation by deer. Deer visit- ing multiple farms may contribute to local area spread of bTB. Focusing risk mitigation efforts on individual deer that are most likely to visit farms may reduce potential bTB transmission.

Denning behaviour of the European badger (Meles meles) correlates with bovine tuberculosis infection status.

Heterogeneities in behaviours of individuals may underpin important processes in evolutionary biology and ecology, including the spread of disease. Modelling approaches can sometimes fail to predict disease spread, which may partly be due to the number of unknown sources of variation in host behaviour. The European badger is a wildlife reservoir for bovine tuberculosis (bTB) in Britain and Ireland, and individual behaviour has been demonstrated to be an important factor in the spread of bTB among badgers and to cattle. Radio-telemetry devices were deployed on 40 badgers from eight groups to investigate patterns of den (sett) use in a high-density population, where each group had one or two main and three to eight outlier setts in their territory. Badgers were located at their setts for 28 days per season for 1 year to investigate how patterns differed between individuals. Denning behaviour may have a strong influence on contact patterns and the transmission of disease. We found significant heterogeneity, influenced by season, sex and age. Also, when controlling for these, bTB infection status interacting with season was highly correlated with sett use. Test-positive badgers spent more time away from their main sett than those that tested negative. We speculate that wider-ranging behaviour of test-positive animals may result in them contacting sources of infection more frequently and/or that their behaviour may be influenced by their disease status. Measures to control infectious diseases might be improved by targeting functional groups, specific areas or times of year that may contribute disproportionately to disease spread.Electronic supplementary materialThe online version of this article (doi:10.1007/s00265-012-1467-4) contains supplementary material, which is available to authorized users.

Patterns of delayed detection and persistence of bovine tuberculosis in confirmed and unconfirmed herd breakdowns in cattle and cattle herds in Great Britain

Approximately 1500/6000 cattle farms that were depopulated during the foot and mouth epidemic in GB in 2001 had been repopulated and subjected to two unrestricted (herd considered free from bovine tuberculosis (bTB)) herd tests. Factors associated with herd breakdown(s) (HBD) and individual cattle reactor status at the second test were investigated. There were 96 HBD in total, with a 3-fold increased risk of HBD in herds that had had a HBD at the first test after restocking. Two mixed effect models were used to investigate factors associated with 324/246,060 reactor cattle at the second bTB test; 228 reactors were at confirmed HBD and 96 at unconfirmed HBD; 253 (79%) reactors at the second test were present and test negative at the first test. In confirmed HBD, the odds of cattle reacting were higher if the restocked farm had a history of bTB before 2001 and if the source and restocked farms were high frequency tested (HFT) farms (routine bTB tests at ≥1 per 2 years). Reacting cattle were more likely to have been born on the restocked farm before the first test after FMD and less likely to have been purchased from a low frequency tested (LFT) farm (routine bTB tests at 3–4 year intervals) after the first test compared with a baseline of cattle purchased from a LFT farm before the first test. Unconfirmed HBD at the second test was more likely when the first test was a confirmed HBD and when there was a history of bTB in the restocked farm. In contrast to confirmed HBD, cattle purchased from a LFT farm after the first test were at increased risk of reacting at an unconfirmed HBD at the second test.We conclude that a farm history of bTB suggests persistence of bTB on the farm. Confirmed tests indicate exposure to bTB for some time indicated by the increased risk from HFT source and restocked farms and a farm history of bTB. The risks for reactors are related to the farm and herd and duration of exposure to these risks. Therefore, the spread of bTB to naïve herds would be reduced if farmers only introduced cattle known not to have been in herds and on farms exposed to bTB. Management of bTB on farms with bTB is complicated because there is undisclosed infection in cattle and environmental contamination.

Active use of coyotes ( Canis latrans) to detect Bovine Tuberculosis in northeastern Michigan, USA

Bovine tuberculosis (bTB) is endemic in white-tailed deer ( Odocoileus virginianus) in northeastern Michigan, USA, and research suggests transmission to cattle. Prevalence of the disease in deer is estimated at 1.8%, but as prevalence decreases the difficulty of detection increases. Research suggests coyotes ( Canis latrans) have a higher prevalence of bTB in Michigan than deer and sampling coyotes may be a more efficient surveillance tool to detect presence or spread of the disease. Coyotes possess suitable ecological characteristics to serve as a sentinel species, assuming transmission between coyotes is not significant. The question of whether free-ranging coyotes shed Mycobacterium bovis, the causative agent of bTB, has not been previously addressed. We actively used coyotes as a sentinel to detect bTB in infected and uninfected counties in Michigan's Northeastern Lower Peninsula. We determined whether bTB infection was present through bacteriologic culture of lymph nodes and tissues containing lesions and cultured oral/nasal swabs and feces to establish shedding. Seventeen of 171 coyotes were M. bovis culture positive, one of which was from a previously uninfected county. All oral, nasal secretions and feces were culture negative suggesting minimal, if any, shedding of M. bovis. Thus, infection of coyotes is likely to occur through ingestion of infected deer carcasses and not from interaction with conspecifics. These findings support previous research suggesting that coyotes are useful sentinels for bTB. The use of coyotes as a sentinel, may allow wildlife managers to detect the spread of bTB into naïve counties. With earlier detection managers may be able to take proactive surveillance measures to detect the disease in deer and reduce the potential risk to domestic livestock and captive deer herds.

Spatial Ecology of Raccoons Related to Cattle and Bovine Tuberculosis in Northeastern Michigan

ABSTRACT In 1995, Mycobacterium bovis, the causative bacterium of bovine tuberculosis (bTB), was detected in 5 beef cattle operations in Alcona County, Michigan, USA. In accordance with Federal law, the operations were depopulated to prevent the spread of bTB. Subsequent wildlife surveillance programs identified high prevalence of M. bovis in mesocarnivores, including raccoons (Procyon lotor), which suggested that raccoons may be complicit in vectoring the pathogen among livestock operations. Our goal was to develop an empirical basis for generating hypotheses about the likelihood for raccoons to mediate the transmission of bTB to livestock. We found intersexual differences in scale‐dependent resource selection and probability of spatial interaction that, under certain circumstances, may form the foundation for a sex‐bias in disease transmission. Spatial dispersion of mixed‐forest patches facilitated overlap of adjacent males, whereas female overlap zones included pastures. Within overlap zones, probabilities of interaction for male‐male and male‐female dyads were greater than for female‐female dyads, although we documented an elevated likelihood of spatial interaction between raccoons and livestock around cattle‐feeding troughs and water sources, regardless of sex. Partial regressions generated by linear models indicated that distance between nearest‐neighbor mixed‐forest patches explained most of this observed variation. These results supported our prediction that forest patches juxtaposed with anthropogenic features fostered social tolerance between males and, thus, facilitated spatial interaction and exploitation of anthropogenic features. In raccoons, sex and landscape composition influenced pathogen transmission potential. We suggest that livestock producers locate livestock feeding and watering features away from forest patches to mitigate future outbreaks of bTB in endemic areas.