Diagnosis Of Bovine Tuberculosis Research Articles

WILDLIFE ON THE MOVE: A HIDDEN TUBERCULOSIS THREAT TO CONSERVATION AREAS AND GAME FARMS THROUGH INTRODUCTION OF UNTESTED ANIMALS.

In South Africa, African buffaloes ( Syncerus caffer ) are one of the wildlife maintenance hosts for bovine tuberculosis (BTB) and play a key role in the spread of the disease to other wildlife species and potentially back to cattle. We report a trace-back investigation following the diagnosis of BTB in a previously BTB-free provincial game reserve, founded in the early 1990s in the North West Province of South Africa (SA). Using the intradermal tuberculin and interferon gamma tests, we detected Mycobacterium bovis infection in captured African buffaloes intended for sale. Detection of M. bovis was confirmed by culture and PCR. Molecular typing of M. bovis isolates from three African buffaloes revealed spoligotype SB0140 and a variable number of tandem repeat genotypes which had been previously isolated from wildlife in the KwaZulu-Natal Province of SA. Diagnosis of BTB in a previously uninfected buffalo population provides evidence that the disease can be introduced into an ecosystem through the translocation of untested plains game species. We further illustrate how BTB can remain unnoticed for considerable periods of time in free-ranging wildlife populations and emphasize the need for validated diagnostic tests for application in suitable and practical monitoring programs. This is especially important for species with maintenance host potential and those in high demand at game auctions.

Evaluation of complementary diagnostic tools for bovine tuberculosis detection in dairy herds from India.

Aim:A cross-sectional study was undertaken to know the herd prevalence and evaluate the single intradermal tuberculin testing (SITT), culture isolation, and polymerase chain reaction (PCR) analysis for the diagnosis of bovine tuberculosis (TB).Materials and Methods:A total of 541 cows of three dairy farms of Bareilly and Mukteshwar were screened by SITT followed by collection of pre-scapular lymph node (PSLN) aspirates (71), milk (54), and blood (71) samples from reactor animals. These clinical samples were processed for culture isolation and direct PCR-based identification and species differentiation.Results:Out of 541 cows screened by SITT, 71 (13.12%) animals were found positive. Mycobacteria were isolated from 3 (4.22%) PSLN aspirate but not from any cultured milk and blood samples. 28 (39.43%) PSLN aspirate and 5 (9.25%) milk samples were positive for Mycobacterium TB (MTB) complex (MTC) by PCR amplification for the IS6110 insertion sequence; however, blood samples were found negative. For species differentiation, multiplex-PCR using 12.7 kb primers was conducted. Out of 28 PSLN aspirate, Mycobacterium bovis was detected in 18 (64.28%) and MTB in 8 (28.57%), whereas 2 aspirate samples (7.14%) were positive for both the species. All the five milk positive samples were positive for M. bovis.Conclusion:Direct detection of bovine TB by a molecular-based method in dairy animals after preliminary screening was appeared to be more sensitive and specific compared to the conventional method (i.e., culture isolation). Its application in form of serial testing methodology for the routine diagnosis and thereafter, culling of infected stock may be suggested for the control programs in dairy herds. The PSLN aspirate was found to be the most suitable specimen for culture isolation and PCR-based detection of Mycobacterium spp. among live infected animals.

Comparison of nine DNA extraction methods for the diagnosis of bovine tuberculosis by real time PCR

ABSTRACT: Bovine tuberculosis is an infectious disease with a high impact on the cattle industry, particularly in developing countries. PCR is a very sensitive method for detection of infectious agents, but the sensitivity of molecular diagnosis is largely dependent on the efficiency of the DNA extraction methods. The objective of this study was to evaluate DNA extraction methods for direct detection of Mycobacterium bovis in bovine tissue. Nine commercial kits for DNA extraction were evaluated when combined with two real time PCRs. The DNeasy Blood & Tissue Kit from QIAGEN showed better performance and sensitivity followed by the DNA Mini Kit RBC and FTA Elute Micro Card. Results suggested that, even when the analytical sensitivity of the qPCR is very high, the extraction method can influence the diagnostic sensitivity.

Detection of wide genetic diversity and several novel strains among non-avium nontuberculous mycobacteria isolated from farmed and wild animals in Hungary.

Besides Mycobacterium avium numerous nontuberculous Mycobacterium (NTM) species exist, which pose constant health risk to both humans and animals. The aim of our study was to identify non-avium NTM isolates from veterinary origin in Hungary, and to detect the occurrence of rifampicin resistance among them. Two hundred and twenty-five strains isolated between 2006 and 2013 from domestic and wild animals and veterinary important samples were identified on the basis of partial DNA sequences of different structural or coding genes, besides commercial kits and multiplex PCR. From 14 different sources, 28 NTM strains and 8 hitherto unidentified strain types were detected. Mycobacterium nonchromogenicum was the most frequently occurring strain (25·78%). Besides, new hosts and mycobacteria-related pathological symptoms were detected. Noticeable rifampicin resistance (42·76%) was found among 159 strains from six different host species. Furthermore, we described the problematics of strain-misidentifications using commercial kits. Our study identified the most common non-avium NTM strains in Hungary, and provided account of their occurrence, host range, and pathogenicity. The detected high rifampicin resistance among the strains isolated mainly from fallow and red deer clearly shows that more attention should be paid to the examination of wild animals especially to those ones which may have contact or shared territory with farmed animals. In domestic animal husbandry the maintenance of tuberculosis free status is of primary importance. As immunological cross-reactions due to NTM hamper the diagnosis of bovine tuberculosis, the precise identification of NTM strains would be essential in the veterinary diagnostics, especially for potentially zoonotic strains. This is the first study investigating the strain diversity of non-avium NTM in Hungary.

A preliminary assessment of new bovine and avian tuberculin in cattle by intra-dermal tests and whole blood interferon gamma assay

The present study reports ante-mortem diagnosis of bovine tuberculosis employing tuberculin test using a new tuberculin PPDB (M. bovis, 3/86) and interferon gamma assay in cattle whole blood culture stimulated using a commercial bovine IFN- γ assay kit. Dairy cattle (87) categorized in groups A, B and C were tested using tuberculin test and gamma interferon (IFN-γ). Fresh batches of bovine PPD (from M. bovis 3/86) and avian PPD (M. avium N–17) were prepared and were standardized by conforming to sterility, safety and potency. For tuberculin testing cervical single intradermal test (SIT) and caudal fold test (CFT) were performed using tuberculins at concentration of 1mg/ml and at the concentration of 0.3mg/ ml as a stimulating antigens in IFN-γ test. Out of 80 cattle (group A + B), 44 (55%) were reactor to tuberculin, 21 (26.25%) non reactor and 15 (18.75%) were inconclusive animals and by IFN-γ test 36 (45%) were M. bovis positive, 10 (12.5%) negative, 13 (16.25%) inconclusive and 21 (26.25%) were M. avium positive animals. In group C (not tuberculin tested) only 4 (57.14%) out of 7 cattle were positive. Relative sensitivity of IFN-γ test (63.88%) was higher than the tuberculin test (52.27%). Our study indicated that skin tests (CFT and SIT) and IFN-γ test can be used for successful control and eradication of bovine tuberculosis as IFN-γ test had higher sensitivity.

Diagnosis of Bovine Tuberculosis in Lactating Cattle and Buffaloes by Comparative Intradermal Tuberculin Test and Bovine Gamma-Interferon Immunoassay

Two hundred lactating animals (158 cattle and 42 buffaloes) of organized and unorganized farms were investigated for the bovine TB using comparative intradermal tuberculin test (CITT) and IFN-y assay. CITT was performed using avian and bovine PPD and IFN-y assay by Mycobacterium bovis gamma interferon test kit. Overall, 14.5% and 11.5% animals were found positive by CITT and IFN-y assay, respectively. However, 22.5% animals were detected TB positive th rough combination of both th e tests. So, both CITT and IFN-y assay, wh en used togeth er lead to more accurate screening for bovine TB in dairy h erd.

Performance of Comparative Cervical Tuberculin Test and Serological Methods with Culturing of Nasal Swab in Diagnosis of Bovine Tuberculosis in Cross Breed Cattle Baghdad Iraq: A Comparative Evaluation

This study was designed to assess the diagnostic value of Rapid Antigen bovine TB antibody test kit (RAT) and any association with cervical comparative tuberculin test (CCTT), (iELISA) and nasal swabs culturing, among based detection of M. bovis infection. A herd of 21 animals aged 1 - 8 years cross bread cattle of college of veterinary medicine. 19 (90.47%) animals had good body condition scores, two bulls included, and 2 (9.52%) cows were fair. Serum samples were collected, analyzed for anti-bovine TB antibody using RAT and iELISA. Also the herd was screened by CCTT. The tests were carried out twice, more than ten month interval, and twelve nasal swabs were taken within second survey. The first survey results revealed prevalence rate: 4 (19.04%) animals considered positive results (one positive and 3 suspected results) for CCTT, while the prevalence rate according to RAT was 10 (47.61%). The difference between the two prevalence rate was significant (McNemar chi-statistic = 4.50, p-value = 0.03) Kappa = 0.215 95% confidence interval: from -0.128 to 0.558; the strength of agreement is considered to be “fair”. The study interprets: sensitivity 30%; specificity 99%. The second survey results revealed prevalence rate according to CCTT was 4 (36.36%), while prevalence rate according to RAT was 5 (45.45%). The difference between the two prevalence was not significant (McNemar chi-statistic = 0.33, p-value = 0.56). Kappa = 0.441 95% confidence interval: from -0.087 to 0.968; the strength of agreement is considered to be “moderate”; sensitivity: 60%; specificity: 83%. All serum samples and nasal swabs gave negative results for iELISA and culturing respectively. The study concluded that RAT was highly specific, easy, labor and time saving, suggesting its use as screening test in bovine tuberculosis, and CCTT could be used to confirm positive animals screened by RAT, while there was no association between RAT, CCTT with body condition scores, iELISA and nasal swabs culture results.

Interpretation Criteria for Comparative Intradermal Tuberculin Test for Diagnosis of Bovine Tuberculosis in Cattle in Maroua Area of Cameroon.

Intradermal tuberculin test (TST) is the choice method for diagnosis of bovine tuberculosis (Tb) in live animals. This work was done to assess the performance of single intradermal comparative cervical tuberculin (SICCT) test in randomly selected cattle in Maroua, Cameroon, against detection of Tb lesions and detection of Tb lesions plus acid fast bacilli in lesions. While 22.28% of slaughtered cattle presented Tb lesions at meat inspection, detection rates of anti-bovine-Tb antibody, Tb lesions, and Tb lesions plus acid fast bacilli were 68.57%, 32.95%, and 22.35%, respectively. SICCT-bovine-Tb positive cattle were 35.29%, 29.41%, 25.88%, 24.7%, and 21.18% at ≥2 mm, ≥2.5 mm, ≥3 mm, ≥3.5 mm, and ≥4 mm cut-offs, respectively. Higher sensitivity and predictive values were obtained at severe interpretations. The best performance was at ≥3 mm and ≥3.5 mm cut-offs. Against detection of Tb lesions, ≥3 mm and ≥3.5 mm showed sensitivity of 67.8% and specificity of 94.7% and 96.5%, respectively. For detection of Tb lesions accompanied with acid fast bacilli in lesions, ≥3 mm and ≥3.5 mm showed sensitivity of 89.4% and specificity of 92.4% and 93.9%, respectively. These findings revealed that interpretations of SICCT-bovine-Tb should be at ≥3 mm and/or ≥3.5 mm cut-offs. Severe interpretation of TST is essential for optimal diagnosis of bovine Tb in cattle in Maroua, Cameroon.

Molecular and immunohistochemical detection ofMycobacterium bovisin formalin-fixed tissues from animals with spontaneous bovine tuberculosis

Bovine tuberculosis (TB) is an infectious and emerging but neglected disease of cattle, caused by Mycobacterium bovis. Diagnostic techniques including histopathology, acid fast staining, immunohistochemistry, polymerase chain reaction (PCR) and real-time PCR were compared for extent of accurate diagnosis of bovine TB. Study was conducted on 16 archival tissue samples collected from suspected cases of bovine tuberculosis. Histopathological studies revealed both well-organized and poorly-organized granulomas in the lungs and lymph nodes. Acid fast bacilli were detected by Ziehl Neelsen's staining in 13 (81.25%) of the 16 suspected cases. Immunohistochemistry using specific polyclonal antibody against M. bovis detected mycobacterial antigen extracellularly in caseous areas as well as intracellularly in macrophages and giant cells. DNA was extracted from formalin-fixed, paraffin-embedded tissues and subjected to IS6110 PCR using T4/T5 and INS1/INS2 primers specific for Mycobacterium tuberculosis complex (MTC) with an expected band size of 123 bp and 245 bp, respectively. The IS6110 PCR assay was positive in 12 out of 16 cases (75%). IS6110 real-time PCR using IS6110_T primers confirmed 6 (37.5%) samples positive for M. bovis. The present investigation indicated that real-time PCR using IS6110_T primers had increased specificity over conventional IS6110 PCR assay and can be used for detecting specific M. bovis infection in animals suspected for bovine tuberculosis.

Diagnosis of bovine tuberculosis: review of main techniques.

Bovine tuberculosis (BTB) remains an important economic and zoonotic problem in Latin America. Traditionally, the fight against BTB is initiated by the implementation of routine diagnostic tests for certification of free properties. The diagnosis of BTB can be made by direct and indirect methods, in which we can mention clinical, post mortem, histopathological, immunological, bacteriological and molecular methods. The renewal of scientific interest in tuberculosis in recent year has led to develop and improve methods of diagnosis, prevention, control and eradication of BTB. The aim of this review is to present and discuss different diagnosis methods of BTB.

Display of Antigens on Polyester Inclusions Lowers the Antigen Concentration Required for a Bovine Tuberculosis Skin Test.

The tuberculin skin test is the primary screening test for the diagnosis of bovine tuberculosis (TB), and use of this test has been very valuable in the control of this disease in many countries. However, the test lacks specificity when cattle have been exposed to environmental mycobacteria or vaccinated with Mycobacterium bovis bacille Calmette-Guérin (BCG). Recent studies showed that the use of three or four recombinant mycobacterial proteins, including 6-kDa early secretory antigenic target (ESAT6), 10-kDa culture filtrate protein (CFP10), Rv3615c, and Rv3020c, or a peptide cocktail derived from those proteins, in the skin test greatly enhanced test specificity, with minimal loss of test sensitivity. The proteins are present in members of the pathogenic Mycobacterium tuberculosis complex but are absent in or not expressed by the majority of environmental mycobacteria and the BCG vaccine strain. To produce a low-cost skin test reagent, the proteins were displayed at high density on polyester beads through translational fusion to a polyhydroxyalkanoate synthase that mediates the formation of antigen-displaying inclusions in recombinant Escherichia coli. Display of the proteins on the polyester beads greatly increased their immunogenicity, allowing for the use of very low concentrations of proteins (0.1 to 3 μg of mycobacterial protein/inoculum) in the skin test. Polyester beads simultaneously displaying all four proteins were produced in a single fermentation process. The polyester beads displaying three or four mycobacterial proteins were shown to have high sensitivity for detection of M. bovis-infected cattle and induced minimal responses in animals exposed to environmental mycobacteria or vaccinated with BCG.

Assessment of the degree of concordance between the results of histopathological examination and bacterial culture in the diagnosis of bovine tuberculosis in Mexico

Bovine tuberculosis is a complex disease that is difficult to diagnose, control and eradicate and negatively impacts many farms. The objective of this study was to assess the degree of concordance between the results of histopathological examination and bacterial culture in the diagnosis of bovine tuberculosis lesions obtained in the laboratories certified by the Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación (Ministry of Agriculture, Animal Production, Rural Development, Fisheries and Feeding) at the national level between January 2009 and December 2012 in Mexico. Tissue samples (10,818) from regular slaughter cattle that did not have tuberculin tests but had lesions suspected of having been caused by tuberculosis were sent to 10 authorized laboratories. Using Cohen’s kappa to measure the reliability of the diagnosis, a general concordance was obtained between the histopathological examination and bacterial culture results with a kappa of 0.634 and a 95% (0.618 – 0.650) confidence interval (CI), which shows good concordance between the two techniques at the national level. The laboratory in Chihuahua had the highest kappa [k=0.784, 95% CI (0.754–0.814)] and the laboratory of the La Laguna Region in the state of Coahuila had a low value of global concordance [k= 0.334, 95% CI (0.257–0.412)]. The number of positive samples in bacterial culture was low in Tamaulipas (21 samples), Sonora (41 samples), and Yucatán (45 samples) because tuberculosis prevalence in those states is ≤ 0.04%. The number of positive samples in bacterial culture was low in Tamaulipas (21 samples), Sonora (41 samples), and Yucatán (45 samples) because tuberculosis prevalence in those states is ≤ 0.04%. The reason for the disagreement between the two tests among some laboratories includes factors such as a lack of economic resources, infrastructure or personnel training. Correct sampling procedures, storage facilities, and shipping and sample processes are important in optimizing the bacteriological and histopathological results and obtaining correct diagnoses and differential diagnoses of bovine tuberculosis.

Isolation and identification of Mycobacterium bovis and Mycobacterium tuberculosis from animal tissues by conventional and molecular method

Tuberculosis is a worldwide contagious and chronic disease of human as well as domestic animals with zoonotic potential. The Mycobacterium bovis and Mycobacterium tuberculosis are the main cause of tuberculosis. It has worldwide distribution with significant effect on animals and has public health importance. Therefore the present study was conducted to determine the prevalence of Mycobacterium bovis and Mycobacterium tuberculosis among the ruminant of district Kohat, Khyber PakhtunKhwa and also to evaluate the sensitivity and specificity of Microscopy and PCR. A total 200 tissue samples of lungs, lymph nodes and liver from cattle, buffaloes, sheep and goats were collected from Abattoir Kohat. All the tissue were first examined by direct smear microscopy by Ziehl Neelsen staining and then subjected to the PCR for the detection of M. bovis and M. tuberculosis. The overall prevalence of tuberculosis was 6.5% by PCR.Prevalence of tuberculosis was recorded in7.87% of lungs samples followed by 5.26% lymph node. Moreover the prevalence was found 5.2%, 4%, 10.6% and 6.5% in cattle, buffalos, Goats and sheep respectively. Furthermorethe sensitivity and specificity of PCR and microscopy in term of detection of TB was determined that PCR was found less sensitive then microscopy because of other species which was not amplified due to non availability of specific primer and were found positive in microscopy.In conclusion PCR is more reliable diagnostic tool for diagnosis of bovine tuberculosis. It is recommended that PCR based diagnostic reference laboratory may be established at district level and Tuberculosis awareness campaign must be arranged.

Bovine tuberculosis: how likely is a skin test reactor to be uninfected?

ACCURATE diagnosis of bovine tuberculosis (TB: infection with Mycobacterium bovis ) in live animals is difficult. A large part of the problem is due to the diagnostic tests being imperfect,...

Mycobacterium tuberculosisexposure of livestock in a German dairy farm: implications forintra vitamdiagnosis of bovine tuberculosis in an officially tuberculosis-free country

Germany has been an officially bovine tuberculosis (bTB)-free (OTF) country since 1996. Gradually rising numbers of bTB herd incidents due to Mycobacterium bovis and M. caprae in North-Western and Southern Germany during the last few years prompted the competent authorities to conduct a nationwide bTB survey in 2013/2014. This led to the detection of a dairy herd in which as many as 55 cattle reacted positively to consecutive intra vitam testing. Test-positive animals lacked visible lesions indicative of bTB at necropsy. Extensive mycobacterial culturing as well as molecular testing of samples from 11 tissues for members of the M. tuberculosis complex (MTC) yielded negative results throughout. However, caseous lymphadenitis of Ln. mandibularis accessorius was observed during meat inspection of a fattening pig from the same farm at regular slaughter at that time. Respective tissue samples tested MTC positive by polymerase chain reaction, and M. tuberculosis T1 family were identified by spoligotyping. Four human reactors within the farmer's family were also found to be immunoreactive. As exposure of livestock to M. tuberculosis is not generally considered, its impact may result in regulatory and practical difficulties when using protocols designed to detect classical bTB, particularly in OTF countries.

Screening putative antigens as stimulators in the Mycobacterium bovis interferon-gamma release assay for cattle

Bovine tuberculosis (BTB) represents not only a significant economic concern, but also an important public health problem. Currently, interferon-gamma (IFN-γ) release assays (IGRAs) are widely used as an adjunct to the tuberculin test (TST) for the diagnosis of BTB. A great number of international studies have demonstrated that the sensitivity of the IFN-γ assay, which uses purified protein derivatives (PPDs) as diagnostic reagents, is superior to that of the TST. However, there are concerns about its specificity, largely because of the cross reactivity of common antigens shared by pathogenic and non-pathogenic mycobacterial species. The use of pathogen-specific antigens theoretically offers the most effective way to improve the specificity of IGRAs. In this study, we evaluated the potential utility of 13 purified recombinant putative antigens, which are highly specific to the Mycobacterium tuberculosis complex, as diagnostic reagents in IGRAs. A CFP-10-ESAT-6 fusion protein (abbreviated CE) displayed the greatest potential, whereas four region of difference 2 (RD2) antigens, especially Rv1985c were identified as potential candidate antigens, and can be included in an IGRA cocktail, together with CE as stimulators in the IFN-γ release assay for the diagnosis of BTB.

English

The causative agent of bovine tuberculosis (BTB) is Mycobacterium bovis, a bacterium belonging to the M. tuberculosis complex (MTC). The definitive diagnosis is achieved through isolation and identification of M. bovis from clinical samples, using a combination of traditional culture and biochemical methods, which is considered the “gold standard”. This procedure is cumbersome and time-consuming. We evaluated a multiplex-PCR (m-PCR) assay for the direct detection of M. bovis DNA from tissue with BTB-suspected lesions. A dairy herd consisting of 270 adult cattle where 34 animals were positive to the tuberculin skin test has been reported. At 30 days after the tuberculin test, all 34 reactive animals were slaughtered and subjected to a necropsy procedure. A pool of tissue samples representative of each animal (lung and mediastinal, scapular and retropharyngeal lymph nodes) were collected and subjected to bacteriological culture and m-PCR. Mycobacterium spp. was isolated in 50% (17/34) of the collected samples. When using m-PCR directly from tissue fragments, it was possible to detect M. bovis in 67.6% (23/34) of the collected samples including 15 samples isolated by bacteriological culture. High performance liquid chromatography (HPLC) was used to differentiate the 17 isolated strains of Mycobacterium spp., from the Mycobacterium tuberculosis complex (MTC) or other Mycobacterium sp. not belonging to the MTC. The use of m-PCR assays directly from tissue samples may be a valid supplementary tool for the post mortem diagnosis of BTB, since this is a a faster and more specific technique than bacterial culturing, reducing the diagnosis time for diagnosis of the disease from three months to two days. Key words: Bovine tuberculosis, high performance liquid chromatography (HPLC), Mycobacterium tuberculosis complex, multiplex polymerase chain reaction (PCR), tissues with macroscopic lesions.

Effect of the inoculation site of bovine purified protein derivative (PPD) on the skin fold thickness increase in cattle from officially tuberculosis free and tuberculosis-infected herds

The official technique for diagnosis of bovine tuberculosis (bTB) worldwide is the tuberculin skin test, based on the evaluation of the skin thickness increase after the intradermal inoculation of a purified protein derivative (PPD) in cattle. A number of studies performed on experimentally infected or sensitized cattle have suggested that the relative sensitivity of the cervical test (performed in the neck) may vary depending on the exact location in which the PPD is injected. However, quantitative evidence on the variation of the test accuracy associated to changes in the site of inoculation in naturally infected animals (the population in which performance of the test is most critical for disease eradication) is lacking.Here, the probability of obtaining a positive reaction (>2 or 4 millimeters and/or presence of local clinical signs) after multiple inoculations of bovine PPD in different cervical and scapular locations was assessed in animals from five bTB-infected herds (818 cattle receiving eight inoculations) using a hierarchical Bayesian logistic regression model and adjusting for the potential effect of age and sex. The effect of the inoculation site was also assessed qualitatively in animals from four officially tuberculosis free (OTF) herds (two inoculations in 210 animals and eight inoculations in 38 cattle). Although no differences in the qualitative outcome of the test were observed in cattle from OTF herds, a statistically important association between the test outcome and the inoculation site in animals from infected herds was observed, with higher probabilities of positive results when the test was performed in the neck anterior area. Our results suggest that test sensitivity may be maximized by considering the area of the neck in which the test is applied, although lack of effect of the inoculation site in the specificity of the test should be confirmed in a larger sample.

Diagnosis of bovine tuberculosis using a metal oxide-based electronic nose.

Electronic noses (e-noses) have been used for environmental monitoring, standardization of medicinal flavourings, food safety tests and diagnosis of infectious diseases based on the statistical analysis of volatile organic compounds (VOCs). Bovine tuberculosis (bTB) is officially diagnosed using the intradermal skin test (IST), which is time-consuming and labour-intensive. Therefore, a more convenient and rapid test with greater sensitivity would be advantageous as prescreening test. In this study, we used a metal oxide sensor (MOS) type e-nose to analyse VOCs in a bTB-infected (n = 11) and bTB-free (n = 10) sera, from cattle whose health status was confirmed using the IST, and pathological and bacteriological examinations. The differences in VOCs from bTB-infected and bTB-free sera detected by the e-nose were statistically analysed using principal components and discriminant factor analyses. bTB-infected and bTB-free sera could be discriminated by MOS type e-nose, and analysing time per sample was only 20 min. VOC analysis using a MOS e-nose was a rapid and automated prescreening method to diagnose bTB, and can be used to select bTB-suspect cattle for IST confirmation. Further studies are required to estimate test sensitivity and specificity. Significance and impact of the study: Bovine tuberculosis (bTB) in cattle is diagnosed using the intradermal skin test (IST); however, this method is very time-consuming and labour-intensive. We analysed volatile organic compounds that are obtained from serum using a metal oxide sensor type of electronic nose to discriminate between TB-infected and TB-free sera. This simple and automated technique will be useful to prescreen bTB-suspects and reduce the time and labour required to perform the IST.

Molecular diagnosis of bovine tuberculosis in bovine and human samples: implications for zoonosis.

To develop emerging diagnostic technique for bovine tuberculosis and to identify its potential risk factors. Bacterial genomic DNA was isolated from bovine milk and human sputum samples and subjected to PCR using specific primer pairs. PCR results were validated using bacteriological cultures. PCR amplification of the targeted DNA fragment of Mycobacterium bovis was successful in 12.33% (37/300) of the bovine samples. Interestingly, 500-bp DNA fragment was also amplified in 6.67% (6/90) of the sputum indicating the possibility of zoonotic transmission. Rearing of livestock in household, unpasteurized milk consumption and smoking were identified as potential risk factors. Results of the study may add value to bovine tuberculosis eradication campaigns to achieve the One Health initiative.