bTB Prevalence Research Articles

Molecular Epidemiology of Mycobacterium bovis in Humans and Cattle.

Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M.bovis), is a serious re-emerging disease in both animals and humans. The evolution of the Multi- and Extensively drug-resistant M.bovis strains (MDR-TB and XDR-TB) represents a global threat to public health. Worldwide, the disease is responsible for great economic losses in the veterinary field, serious threat to the ecosystem, and about 3.1% of human TB cases, up to 16% in Tanzania. Only thorough investigation to understand the pathogen's epidemiology can help in controlling the disease and minimizing its threat. For this purpose, various tools have been developed for use in advanced molecular epidemiological studies of bTB, either alone or in combination with standard conventional epidemiological approaches. These techniques enable the analysis of the intra- and inter-species transmission dynamics of bTB. The delivered data can reveal detailed insights into the source of infection, correlations among human and bovine isolates, strain diversity and evolution, spread, geographical localization, host preference, tracing of certain virulence factors such as antibiotic resistance genes, and finally the risk factors for the maintenance and spread of M.bovis. They also allow for the determination of epidemic and endemic strains. This, in turn, has a significant diagnostic impact and helps in vaccine development for bTB eradication programs. The present review discusses many topics including the aetiology, epidemiology and importance of M.bovis, the prevalence of bTB in humans and animals in various countries, the molecular epidemiology of M.bovis, and finally applied molecular epidemiological techniques.

Development of risk-based trading farm scoring system to assist with the control of bovine tuberculosis in cattle in England and Wales

Identifying and ranking cattle herds with a higher risk of being or becoming infected on known risk factors can help target farm biosecurity, surveillance schemes and reduce spread through animal trading. This paper describes a quantitative approach to develop risk scores, based on the probability of infection in a herd with bovine tuberculosis (bTB), to be used in a risk-based trading (RBT) scheme in England and Wales. To produce a practical scoring system the risk factors included need to be simple and quick to understand, sufficiently informative and derived from centralised national databases to enable verification and assess compliance. A logistic regression identified herd history of bTB, local bTB prevalence, herd size and movements of animals onto farms in batches from high risk areas as being significantly associated with the probability of bTB infection on farm. Risk factors were assigned points using the estimated odds ratios to weight them. The farm risk score was defined as the sum of these individual points yielding a range from 1 to 5 and was calculated for each cattle farm that was trading animals in England and Wales at the start of a year. Within 12 months, of those farms tested, 30.3% of score 5 farms had a breakdown (sensitivity). Of farms scoring 1–4 only 5.4% incurred a breakdown (1-specificity). The use of this risk scoring system within RBT has the potential to reduce infected cattle movements; however, there are cost implications in ensuring that the information underpinning any system is accurate and up to date.

Sensitivity of Bovine Tuberculosis Surveillance in Wildlife in France: A Scenario Tree Approach.

Bovine tuberculosis (bTB) is a common disease in cattle and wildlife, with an impact on animal and human health, and economic implications. Infected wild animals have been detected in some European countries, and bTB reservoirs in wildlife have been identified, potentially hindering the eradication of bTB from cattle populations. However, the surveillance of bTB in wildlife involves several practical difficulties and is not currently covered by EU legislation. We report here the first assessment of the sensitivity of the bTB surveillance system for free-ranging wildlife launched in France in 2011 (the Sylvatub system), based on scenario tree modelling. Three surveillance system components were identified: (i) passive scanning surveillance for hunted wild boar, red deer and roe deer, based on carcass examination, (ii) passive surveillance on animals found dead, moribund or with abnormal behaviour, for wild boar, red deer, roe deer and badger and (iii) active surveillance for wild boar and badger. The application of these three surveillance system components depends on the geographic risk of bTB infection in wildlife, which in turn depends on the prevalence of bTB in cattle. We estimated the effectiveness of the three components of the Sylvatub surveillance system quantitatively, for each species separately. Active surveillance and passive scanning surveillance by carcass examination were the approaches most likely to detect at least one infected animal in a population with a given design prevalence, regardless of the local risk level and species considered. The awareness of hunters, which depends on their training and the geographic risk, was found to affect surveillance sensitivity. The results obtained are relevant for hunters and veterinary authorities wishing to determine the actual efficacy of wildlife bTB surveillance as a function of geographic area and species, and could provide support for decision-making processes concerning the enhancement of surveillance strategies.

Occurrence and Distribution of bovine tuberculosis (Mycobacterium bovis) in Slaughtered cattle in the abattoirs of Bauchi State, Nigeria.

Aim:This study was aimed to determine the prevalence of bovine tuberculosis (bTB) in slaughtered cattle in Bauchi State, Nigeria. The cause (s) of grossly suspected bTB lesions encountered at the abattoirs during post-mortem (PM), as whether due to Mycobacterium bovis alone or together with other acid fast bacilli (AFB).Materials and Methods:A cross-sectional abattoir based study was conducted on 800 cattle slaughtered in the Northern, Central and Southern zonal abattoirs of Bauchi State, Nigeria, from June to August 2013; using PM meat inspection, Ziehl-Neelsen staining (ZN) and confirmatory polymerase chain reaction (PCR) techniques.Results:The occurrence of bTB lesions from the organs of slaughtered cattle in Bauchi State, showed that the lungs had the highest number of suspected tissues 65 (54.20%), followed by the lymph nodes 28 (23.30%) while the heart, liver, spleen, intestines and mammary glands had the other 8.3%, 6.7%, 5.0%, 1.7%, and 0.8%, suspected tissues respectively. By ZN microscopic staining all 100% (2/2) of the intestines were positive for bTB, followed by the heart with 50% (5/10), then the lungs 29.23% (19/65); while the liver, lymph nodes, and spleen had 25%, 21.43% and 16.67% respectively were tested positive for bTB. It was only the mammary gland that tested negative for bTB in all the suspected tissues sampled. By PCR, the intestines had the highest positive bTB with 100% (2/2), followed by the liver with 12.5% (1/8), and then the lungs with 7.8% (5/65). The lymph nodes had 7.14% (2/28) tissues that tested positive for bTB. However, the spleen, heart and mammary gland were all tested negative with 0%; indicating that the false positive for bTB detected by ZN were confirmed by PCR. While based on the location of the abattoirs in the three senatorial zones of Bauchi State, Bauchi zonal abattoir had the highest number of suspected bTB cases 75 (62.50%), followed by Katagum zonal slaughter house with 32 (26.7%) and then Misau with 13 (10.8%). By the ZN staining technique, there were 25 (33.33%) positivity in Bauchi Zonal abattoir, while Katagum and Misau abattoirs had 9 (28.13%) and 1 (7.72%) positive respectively. By the PCR technique, 9 (12.00%), 1 (3.13%) and 0 (0.00%) positive cases were recorded for Bauchi, Katagum and Misau abattoirs respectively.Conclusion:The present study estimated the prevalence rate of bTB in Bauchi State, using PM, ZN and PCR techniques at 15.0%, 29.16% and 8.33%, respectively. Bovine TB lesions found at PM were not all due to M. bovis alone, as other MTBC and AFB organisms may cause bTB-like lesions that were excluded by PCR specific primers. The prevalence of bTB was higher in Bauchi abattoir that supplies larger population of the state with beef. These findings also demonstrate the urgent need for public health authorities in the state to intervene in the control of the zoonotic bTB.

Detection of Mycobacterium bovis in Organs of Slaughtered Cattle by DNA-Based Polymerase Chain Reaction and Ziehl-Neelsen Techniques in Bauchi State, Nigeria.

Bovine tuberculosis is a chronic, infectious, and contagious zoonotic disease of domestic animals, wild animals, and humans. It also poses a public health threat and economic losses. This study was aimed at determining the prevalence of bovine tuberculosis in slaughtered cattle, based on PM meat inspection, Ziehl-Neelsen staining, and PCR techniques in Bauchi State, Nigeria. A Prospective study was conducted on 800 cattle slaughtered in the three Zonal abattoirs of Bauchi State, Nigeria. One hundred and twenty (15%) tissues from different organs had suspected bTB lesions at PM. Out of the samples examined 35 (29.2%) were AFB positive by ZN and 10 (8.3%) were confirmed positive for M. bovis by PCR, with an overall prevalence of 29.16% and 8.33%, respectively. Female had a higher prevalence rate than male cattle at 16.66% and 12.5 % by ZN and 5.00% and 3.33% by PCR, respectively (P>0.05, χ 2 = 0.218). However, there was a statistically significant association (P<0.05, χ 2 = 7.002) between detection of bTB and the age of cattle. ZN revealed that cattle aged 6 years and above had the highest number of positive bTB cases 67.9%, while cattle aged 3–5 years had the lowest 14.81%. PCR technique revealed that the cattle aged 6 and above years also had the highest percentage positive M. bovis cases of 22.84%, whereas cattle aged 3–5 years had the lowest and the overall prevalence rate of 8.33%. The study found a high infection rate of bTB among cattle and majority of the lesions 54.2% were from lungs. The prevalence of bTB was higher in Bauchi metropolitan abattoir which supplies larger population of the state with beef.

Prevalence of Bovine Tuberculosis in Egyptian Cattle and the Standardization of the Interferon-gamma Assay as an Ancillary Test.

Bovine tuberculosis (bTB) caused primarily by Mycobacterium bovis continues to cause significant losses in the cattle industry and is a major public health problem. Despite its worldwide application, the IFN-γ assay has not been applied in Egypt. The aim of this study was to determine the appropriate cut-off value of IFN-γ assay to complement the skin test screening in Egypt. The relative sensitivity (Ser ) of PPD and antigen cocktail-based IFN-γ assays (IFN-γ-BA and IFN-γ-EC) was analysed retrospectively, relative to bTB confirmatory tests (culture and PCR), using single cervical tuberculin (SCT) test reactors during 2011-2013. The absolute specificity (Sp) was studied using blood samples collected from cattle from one bTB-free herd. Analysis of the bTB database-generated sheets indicates the infection rate had decreased from 2009 to 2012 and then increased in 2013. The disease is concentrated in the Egyptian Nile Delta and Valley relative to elsewhere in the country. The cut-offs for IFN-γ-EC assay could be optimized to provide higher sensitivity, comparable to cut-offs for IFN-γ-BA assay. Data analysis suggests (PPDbOD >0.1, PPDbOD -NILOD >0.05 and PPDbOD >PPDaOD ) and (ECOD -NILOD ≥0.1) cut-off strategies to get optimal IFN-γ-BA and IFN-γ-EC assays results respectively. To our knowledge, this is the first report describing the prevalence of bTB in cattle in Egypt and pointing out the appropriate cut-off criteria to optimize IFN-γ assay as a routine ancillary test for diagnosis of bTB in Egypt.

Variance components for susceptibility to Mycobacterium bovis infection in dairy and beef cattle.

BackgroundInfection of livestock with bovine tuberculosis (bTB; Mycobacterium bovis) is of major economical concern in many countries; approximately 15 000 to 20 000 cattle are infected per year in Ireland. The objective of this study was to quantify the genetic variation for bTB susceptibility in Irish dairy and beef cattle.MethodsA total of 105 914 cow, 56 904 heifer and 21 872 steer single intra-dermal comparative tuberculin test records (i.e., binary trait) collected from the years 2001 to 2010 from dairy and beef herds were included in the analysis. Only animal level data pertaining to periods of herd bTB infection were retained. Variance components for bTB were estimated using animal linear and threshold mixed models and co-variances were estimated using sire linear mixed models.ResultsUsing a linear model, the heritability for susceptibility to bTB in the entire dataset was 0.11 and ranged from 0.08 (heifers in dairy herds) to 0.19 (heifers in beef herds) among the sub-populations investigated. Differences in susceptibility to bTB between breeds were clearly evident. Estimates of genetic correlations for bTB susceptibility between animal types (i.e., cows, heifers, steers) were all positive (0.10 to 0.64), yet different from one. Furthermore, genetic correlations for bTB susceptibility between environments that differed in herd prevalence of bTB ranged from 0.06 to 0.86 and were all different from one.ConclusionsGenetic trends for bTB susceptibility observed in this study suggest a slight increase in genetic susceptibility to bTB in recent years. Since bTB is of economic importance and because all animals are routinely tested at least once annually in Ireland and some other countries, the presence of genetic variation for bTB susceptibility suggests that bTB susceptibility should be included in a national breeding program to halt possible deterioration in genetic susceptibility to bTB infection.

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.

Bovine tuberculosis in Northern Ireland: Risk factors associated with time from post-outbreak test to subsequent herd breakdown

Compulsory bovine tuberculosis testing has been implemented since 1959 in Northern Ireland. Initial rapid progress in the eradication of the disease was followed by a situation where disease levels tended to fluctuate around a low level. This study explores recrudescence of bovine tuberculosis (bTB) in Northern Ireland herds by assessing risk factors associated with time from the six-month post-outbreak skin test until a further herd breakdown. Bovine herds (n=3377) were recruited in 2002 and 2003 and their survival analysed using Kaplan–Meier survival estimates and a Cox proportional hazards model, with follow-up extending to August 2008. Exclusion criteria applied for study entry were bTB infection in a contiguous herd, changing of post restriction test to one of a higher risk status or chronic infection. Chronic infection was defined as any situation where disclosure preceded the post-outbreak test by two years or more. The application of these exclusion criteria meant that herds recruited to the study were largely cleared of infection and not directly contiguous to other infected herds. Of the 3377 herds, 1402 (41.5%) suffered a further herd breakdown before the end of follow-up. Median survival time was 582 days (interquartile range=336–1002 days). Breakdown severity (defined as the number of Single Intradermal Comparative Tuberculin Test (SICTT) reactors at disclosure test), local bTB prevalence, herd size and type were identified as significant risk factors (p<0.05), as was the purchase of higher numbers (n>27.38 per year) of cattle. Consistent with other studies this work shows bTB confirmation to not be predictive of a future herd breakdown. This work shows bTB history as not being a risk factor for a future breakdown. This result could be reflective of the exclusion criteria used in the study, which may have selected for incidents where historical status was of less importance.

Identification of potential biomarkers of disease progression in bovine tuberculosis

Bovine tuberculosis (bTB) remains an important animal and zoonotic disease in many countries. The diagnosis of bTB is based on tuberculin skin test and IFN-γ release assays (IGRA). Positive animals are separated from the herd and sacrificed. The cost of this procedure is difficult to afford for developing countries with high prevalence of bTB; therefore, the improvement of diagnostic methods and the identification of animals in different stages of the disease will be helpful to control the infection. To identify biomarkers that can discriminate between tuberculin positive cattle with and without tuberculosis lesions (ML+ and ML−, respectively), we assessed a group of immunological parameters with three different classification methods: lineal discriminant analysis (LDA), quadratic discriminant analysis (QDA) and K nearest neighbors (k-nn). For this purpose, we used data from 30 experimentally infected cattle. All the classifiers (LDA, QDA and k-nn) selected IL-2 and IL-17 as the most discriminatory variables. The best classification method was LDA using IL-17 and IL-2 as predictors. The addition of IL-10 to LDA improves the performance of the classifier to discriminate ML-individuals (93.3% vs. 86.7%). Thus, the expression of IL-17, IL-2 and, in some cases, IL-10 would serve as an additional tool to study disease progression in herds with a history of bTB.

Comparison of intervention methods for reducing human exposure to Mycobacterium bovis through milk in pastoralist households of Tanzania

Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a disease of zoonotic concern, especially in countries with no control programs in livestock and where routine pasteurization of milk is not practiced. In Tanzania, bTB is widespread in livestock and has been diagnosed in humans; however, herd bTB testing is primarily carried out for bTB-free certification in commercial dairy herds at the expense of the dairy cattle owner. For rural livestock holders, such an expense is prohibitive, and consequently there is no control of bTB in most areas. Although effective long-term solutions to control bTB in livestock are desirable, there is a need to assess the effect of preventive measures on reducing human exposure to bTB in such settings. We utilized locally relevant cattle herd characteristics and management data from the Health for Animals and Livelihood Improvement (HALI) project in south-central Tanzania to build a Reed-Frost model that compared the efficacy of alternative methods aimed at reducing the exposure of humans to infectious milk from a typical pastoralist cattle herd. During a 10-year simulation period, the model showed that boiling milk 80% of the time is necessary to obtain a reduction in liters of infectious milk approximately equivalent to what would be obtained with a standard 2-year testing and removal regimen, and that boiling milk was more effective than animal test and removal early in the time period.In addition, even with testing and removing infected cattle, a residual risk of exposure to infectious milk remained due to imperfect sensitivity of the skin test and a continuous risk of introduction of infectious animals from other herds. The model was sensitive to changes in initial bTB prevalence but not to changes in herd size. In conclusion, continuous complimentary treatment of milk may be an effective strategy to reduce human exposure to M. bovis-infected milk in settings where bTB is endemic and a comprehensive bTB control program is yet to be implemented.

A retrospective study of rabies cases at Techiman Municipal, Ghana, 2009 – 2012

Background: Bovine Tuberculosis (bTB) byM. bovis is a chronic infectious disease of cattle that can represent a risk to human health. bTB European Eradication Plans are based on tuberculin testing and slaughtering of reactive subjects. Despite controlmeasures have been applied in Italy since 1964, illness is still present in Sicily. On 2012, regional official data reported an herd infection prevalence of 3.09% and an herd incidence of 2.37%. In the same year, head prevalence was of 0.70%. This study has analyzed the results of the control activity performed on cattle farm in Sicily between 2009-2012, with the aim to evaluate the bTB prevalence and incidence. Methods &Materials: The processed data are the results of the official testes carried out by the Veterinary Services of Sicily during the reference years (2009-2012). Population was the number of cattle farms insistent in each of the nine province of Sicily and the number of animals in each province. In the scope of this population were considered, for each year, the “cases”, ie all farms and animals tested positive for tuberculosis (prevalence) and the “new cases”, ie the new positive herds (incidence). Results: During 2009-2012, the prevalence of bTB infection in the herds of the Sicilian territory has remained around an average value of 3.47%. Adecreasewas registered in 2012 (3.09%) and apeak in 2011 (3.65%). The incidence amounted around an average value of 2.55%, with a decrease of 2.37% in 2012 and a peak of 2.73% in 2010. Head prevalence has showed a decreasing trend during the study period, going from 1.15% in 2009 to 0.70% in 2012. Conclusion: The results show that both the bTB prevalence and incidence of herds that the head prevalence has remained almost unchanged from2009 to 2011. A slight dropwas registered in 2012. The study confirmed that bTB is present in cattle in Sicily and the risk of the transmission of the disease to humans is possible. It is appropriate to make further investigations for identifying the risk factors that influence the persistence of infection in Sicily. Collaboration between the veterinary and the medical sectors could be encouraged.

Prevalence of Bovine Tuberculosis and Risk Factor Assessment in Cattle in Rural Livestock Areas of Govuro District in the Southeast of Mozambique

BackgroundBovine tuberculosis (bTB), caused by Mycobacterium bovis, is an infectious disease of cattle that also affects other domestic animals, free-ranging and farmed wildlife, and also humans. In Mozambique, scattered surveys have reported a wide variation of bTB prevalence rates in cattle from different regions. Due to direct economic repercussions on livestock and indirect consequences for human health and wildlife, knowing the prevalence rates of the disease is essential to define an effective control strategy.Methodology/Principal findingsA cross-sectional study was conducted in Govuro district to determine bTB prevalence in cattle and identify associated risk factors. A representative sample of the cattle population was defined, stratified by livestock areas (n = 14). A total of 1136 cattle from 289 farmers were tested using the single comparative intradermal tuberculin test. The overall apparent prevalence was estimated at 39.6% (95% CI 36.8–42.5) using a diagnostic threshold cut-off according to the World Organization for Animal Health. bTB reactors were found in 13 livestock areas, with prevalence rates ranging from 8.1 to 65.8%. Age was the main risk factor; animals older than 4 years were more likely to be positive reactors (OR = 3.2, 95% CI: 2.2–4.7). Landim local breed showed a lower prevalence than crossbred animals (Landim × Brahman) (OR = 0.6, 95% CI: 0.4–0.8).Conclusions/SignificanceThe findings reveal an urgent need for intervention with effective, area-based, control measures in order to reduce bTB prevalence and prevent its spread to the human population. In addition to the high prevalence, population habits in Govuro, particularly the consumption of raw milk, clearly may potentiate the transmission to humans. Thus, further studies on human tuberculosis and the molecular characterization of the predominant strain lineages that cause bTB in cattle and humans are urgently required to evaluate the impact on human health in the region.

Bovine tuberculosis in Rwanda: Prevalence and economic impact evaluation by meat inspection at Société des Abattoirs de Nyabugogo-Nyabugogo Abattoir, Kigali.

Despite the significant public health burden of bovine tuberculosis (bTB) in Rwanda, the prevalence of bTB is poorly documented. This study was conducted to estimate the prevalence of bTB in cattle using gross examination of granulomatous lesions, to identify mycobacteria species in suspected samples, and to evaluate the economic impact of meat condemnation based on bTB-like lesions in the meat industry in Rwanda. Routine meat inspection was conducted at Société des Abattoirsde Nyabugogo (SABAN)-Nyabugogo Abattoir. Tissue samples including 31 lymph nodes, 3 lungs and 2 livers were obtained from cattle of different ages with gross tuberculous lesions. Mycobacterium bovis was identified using microscopy with Kinyoun staining and isolation of mycobacterial species in culture on Löwenstein-Jensen and Colestos media, further identified using biochemical tests. Our findings, based on culture and postmortem results, show that the prevalence of bTB is 0.5%(0.587*148/16753), with an overall gross tuberculous lesion prevalence of 0.9% (148/16753). The presence of lesions were higher in cattle aged 2 years and older (1.6% vs. 0.6%, p &lt; 0.05) and higher in females than in males (1.4% vs. 0.6%, p &lt; 0.05). Of the 36 samples tested, 26 (72.2%) were positive by microscopic examination with Kinyoun staining while M. bovis was culture-confirmed in 21 (58.7%) cases. Bovine tuberculosis caused condemnation of 1683.5 kg of meat, resulting in an estimated loss of $4810. Our findings indicate that the prevalence of bTB in Rwanda is significant, and that bTB is a major cause of meat condemnation requiring continued implementation of surveillance and control measures. Furthermore, the results from this study also show important variations in sensitivity of the different tests that were used to determine the prevalence of bTB in cattle in Rwanda.

Bovine tuberculosis in Rwanda : prevalence and economic impact evaluation by meat inspection at Societe d'Abattoir de Nyabugogo-Nyabugogo Abattoir, Kigali : original research

Despite the significant public health burden of bovine tuberculosis (bTB) in Rwanda, the prevalence of bTB is poorly documented. This study was conducted to estimate the prevalence of bTB in cattle using gross examination of granulomatous lesions, to identify mycobacteria species in suspected samples, and to evaluate the economic impact of meat condemnation based on bTB-like lesions in the meat industry in Rwanda. Routine meat inspection was conducted at Societe d'Abattoir de Nyabugogo (SABAN)-Nyabugogo Abattoir. Tissue samples including 31 lymph nodes, 3 lungs and 2 livers were obtained from cattle of different ages with gross tuberculous lesions. Mycobacterium bovis was identified using microscopy with Kinyoun staining and isolation of mycobacterial species in culture on Lowenstein-Jensen and Colestos media, further identified using biochemical tests. Our findings, based on culture and postmortem results, show that the prevalence of bTB is 0.5% (0.587*148/16753), with an overall gross tuberculous lesion prevalence of 0.9% (148/16753). The presence of lesions were higher in cattle aged 2 years and older (1.6% vs. 0.6%, p < 0.05) and higher in females than in males (1.4% vs. 0.6%, p < 0.05). Of the 36 samples tested, 26 (72.2%) were positive by microscopic examination with Kinyoun staining while M. bovis was culture-confirmed in 21 (58.7%) cases. Bovine tuberculosis caused condemnation of 1683.5 kg of meat, resulting in an estimated loss of $4810. Our findings indicate that the prevalence of bTB in Rwanda is significant, and that bTB is a major cause of meat condemnation requiring continued implementation of surveillance and control measures. Furthermore, the results from this study also show important variations in sensitivity of the different tests that were used to determine the prevalence of bTB in cattle in Rwanda.

Influence of Porcine Circovirus Type 2 Infections on Bovine Tuberculosis in Wild Boar Populations

The wild boar is an important reservoir of bovine tuberculosis (bTB) in south-western Spain. Some risk factors such as wild boar density or age have been associated with the presence of high prevalences of bTB in wild boar. However, the influence of other risk factors such as co-infections with other pathogens has not yet been studied. This work aims to assess the influence of porcine circovirus type 2 (PCV-2) infection on bTB prevalence and bTB lesional patterns observed in wild boar. The presence of bTB-like lesions was evaluated in 551 hunted wild boar from 11 different game estates in south-western Spain, with a known history of bTB. Tuberculosis prevalences in each estate were calculated based on the percentage of animals found with bTB-like lesions. The percentage of animals with generalized bTB lesional patterns (bTB lesions in more than one organ) was also assessed. The prevalence of PCV-2 was studied in each estate using a specific PCR assay. The relationship between PCV-2 and bTB prevalences and between PCV-2 infections and the presence of generalized lesional patterns in wild boar were analysed. A statistical relationship between the prevalences of bTB and PCV-2 was found, with bTB prevalences being higher in estates where prevalences of PCV-2 were high. On the other hand, animals infected with PCV-2 were more likely to develop a generalized lesional pattern. Porcine circovirus type 2 prevalences seem to be associated with prevalences of bTB in wild boar. PCV-2 infection may aggravate the development and severity of bTB, favouring the presence of generalized lesional patterns and raising the risk of contagion in these estates. The implementation of sanitary measures that focus on the control of PCV-2 infection may be necessary as a preliminary measure in bTB control programmes for wild boar.

First-Time Detection of Mycobacterium bovis in Livestock Tissues and Milk in the West Bank, Palestinian Territories

BackgroundBovine tuberculosis, bTB, is classified by the WHO as one of the seven neglected zoonontic diseases that cause animal health problems and has high potential to infect humans. In the West Bank, bTB was not studied among animals and the prevalence of human tuberculosis caused by M. bovis is unknown. Therefore, the aim of this study was to estimate the prevalence of bTB among cattle and goats and identify the molecular characteristics of bTB in our area.Methodology/principal findingsA total of 208 tissue samples, representing 104 animals, and 150 raw milk samples, obtained from cows and goats were examined for the presence of mycobacteria. The tissue samples were collected during routine meat inspection from the Jericho abattoir. DNA was extracted from all samples, milk and tissue biopsies (n = 358), and screened for presence of TB DNA by amplifying a 123-bp segment of the insertion sequence IS6110. Eight out of 254 animals (3.1%) were found to be TB positive based on the IS6110-PCR. Identification of M. bovis among the positive TB samples was carried out via real time PCR followed by high resolution melt curve analysis, targeting the A/G transition along the oxyR gene. Spoligotyping analysis revealed a new genotype of M. bovis that was revealed from one tissue sample.SignificanceDetection of M. bovis in tissue and milk of livestock suggests that apparently healthy cattle and goats are a potential source of infection of bTB and may pose a risk to public health. Hence, appropriate measures including meat inspection at abattoirs in the region are required together with promotion of a health campaign emphasizing the importance of drinking pasteurized milk. In addition, further studies are essential at the farm level to determine the exact prevalence of bTB in goats and cattle herds in the West Bank and Israel.

Tuberculosis Epidemiology in Islands: Insularity, Hosts and Trade

Because of their relative simplicity and the barriers to gene flow, islands are ideal systems to study the distribution of biodiversity. However, the knowledge that can be extracted from this peculiar ecosystem regarding epidemiology of economically relevant diseases has not been widely addressed. We used information available in the scientific literature for 10 old world islands or archipelagos and original data on Sicily to gain new insights into the epidemiology of the Mycobacterium tuberculosis complex (MTC). We explored three nonexclusive working hypotheses on the processes modulating bovine tuberculosis (bTB) herd prevalence in cattle and MTC strain diversity: insularity, hosts and trade. Results suggest that bTB herd prevalence was positively correlated with island size, the presence of wild hosts, and the number of imported cattle, but neither with isolation nor with cattle density. MTC strain diversity was positively related with cattle bTB prevalence, presence of wild hosts and the number of imported cattle, but not with island size, isolation, and cattle density. The three most common spoligotype patterns coincided between Sicily and mainland Italy. However in Sicily, these common patterns showed a clearer dominance than on the Italian mainland, and seven of 19 patterns (37%) found in Sicily had not been reported from continental Italy. Strain patterns were not spatially clustered in Sicily. We were able to infer several aspects of MTC epidemiology and control in islands and thus in fragmented host and pathogen populations. Our results point out the relevance of the intensity of the cattle commercial networks in the epidemiology of MTC, and suggest that eradication will prove more difficult with increasing size of the island and its environmental complexity, mainly in terms of the diversity of suitable domestic and wild MTC hosts.

Factors associated with bovine tuberculosis confirmation rates in suspect lesions found in cattle at routine slaughter in Great Britain, 2003–2008

Bovine tuberculosis (bTB) is one of the most complex and intractable animal health problems facing the British cattle industry today. The inspection of carcasses from cattle sent to slaughter is part of routine surveillance for bTB in Great Britain (GB). Tissue with suspect lesions from cattle from herds previously considered uninfected with bTB is sent to the Animal Health and Veterinary Laboratories Agency (AHVLA) for culture and histopathological examination for Mycobacterium bovis infection. In this study, risk factors for confirmation of infection in suspect bTB lesions found at routine slaughter of cattle from officially bTB-free (OTF) herds in GB were investigated. The study sample included the first record of a suspect lesion in a bovine from any OTF herd identified during post-mortem inspection between 2003 and 2008. There were 3663 submissions from 151 slaughterhouses of which 2470 (67.4%) were confirmed as culture positive for M. bovis. Logistic regression analysis with a random intercept for slaughterhouse was used to investigate relationships between bTB confirmation and animal and herd-level risk factors. Slaughterhouse of post mortem and the following factors related to bTB prevalence were significant predictors of confirmation probability: region of farm of origin of the animal, the testing interval for routine field surveillance for bTB on the farm, number of reactors in the last bTB incident on the farm within the last 4 years, if applicable, the animal's date of birth and the year of animal's slaughter. The modelled predicted population averaged probabilities for confirmation varied from 0.14 to 0.90 between slaughterhouses. Differences in the detection of cattle with bTB between British slaughterhouses warrant further study.

Reducing Eurasian wild boar (Sus scrofa) population density as a measure for bovine tuberculosis control: Effects in wild boar and a sympatric fallow deer (Dama dama) population in Central Spain

Research on management of bovine tuberculosis (bTB) in wildlife reservoir hosts is crucial for the implementation of effective disease control measures and the generation of practical bTB management recommendations. Among the management methods carried out on wild species to reduce bTB prevalence, the control of population density has been frequently used, with hunting pressure a practical strategy to reduce bTB prevalence. However, despite the number of articles about population density control in different bTB wildlife reservoirs, there is little information regarding the application of such measures on the Eurasian wild boar (Sus scrofa), which is considered the main bTB wildlife reservoir within Mediterranean ecosystems.This study shows the effects of a management measure leading to a radical decrease in wild boar population density at a large hunting estate in Central Spain, in order to assess the evolution of bTB prevalence in both the wild boar population and the sympatric fallow deer population.The evolution of bTB prevalence was monitored in populations of the two wild ungulate species over a 5-year study period (2007–2012). The results showed that bTB prevalence decreased in fallow deer, corresponding to an important reduction in the wild boar population. However, this decrease was not homogeneous: in the last season of study there was an increase in bTB-infected male animals. Moreover, bTB prevalence remained high in the remnant wild boar population.