Outbreak Of Bovine Tuberculosis Research Articles

A review of bovine tuberculosis transmission risk in European wildlife communities

Abstract Understanding how disease moves through wildlife communities is essential to managing outbreaks of zoonotic diseases across the globe. Bovine tuberculosis is a disease caused by the bacterium Mycobacterium bovis that can threaten domestic and wildlife species. The mechanism by which Mycobacterium bovis is spread between species is still poorly understood. Previous reviews are limited in the breadth of species considered and are primarily concerned with transmission from wildlife to domestic species. We conducted a review and analysis of Mycobacterium bovis prevalence rates in European wildlife species to identify species of concern for the transmission of bovine tuberculosis in a wildlife community. We subsequently conducted a narrative review of these species assessing the risk of Mycobacterium bovis transmission in a wildlife community based on available literature. We calculated weighted mean disease prevalence rates to be highest in fallow deer (Dama dama, 20%), Eurasian badgers (Meles meles, 11%), wild boar (Sus scrofa, 9%) and red foxes (Vulpes vulpes, 4%). We considered these species to be of particular concern for the transmission of Mycobacterium bovis and selected them as the focus of our narrative review and risk assessment. Our risk assessment considered disease pathology, spatiotemporal activity patterns and animal behaviour as factors affecting the likelihood of Mycobacterium bovis transmission between wildlife species. We found that prior research has principally focused on a few individual species, but that Mycobacterium bovis transmission through a wildlife community is likely more complex. We determined that disease transmission between multiple species may compound the severity of an outbreak of bovine tuberculosis. Broad, multi‐species sampling campaigns and standardised Mycobacterium bovis testing protocols should be implemented in future studies. We also determined that an in‐depth analysis of spatiotemporal overlap between species was needed to better assess the risk of transmission between wildlife species.

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.

Complete Genome Sequences of Mycobacterium bovis Strains Affiliated with Bovine Tuberculosis Outbreaks in Canada in 2016 and 2018.

Mycobacterium bovis is the primary causative agent of bovine tuberculosis, a zoonotic infectious disease that presents a risk to public health, livestock, and wildlife. Here, we report complete genome sequences of two Mycobacterium bovis strains affiliated with bovine tuberculosis outbreaks in Canadian cattle farms in 2016 and 2018.

Genomic analysis of an outbreak of bovine tuberculosis in a man-made multi-host species system: A call for action on wildlife in Brazil.

We report on a 15-year-long outbreak of bovine tuberculosis (bTB) in wildlife from a Brazilian safari park. A timeline of diagnostic events and whole-genome sequencing (WGS) of 21 Mycobacterium bovis isolates from deer and llamas were analyzed. Accordingly, from 2003 to 2018, at least 16 animals, from eight species, died due to TB, which is likely an underestimated number. In three occasions since 2013, the deer presented positive tuberculin tests, leading to the park closure and culling of all deer. WGS indicated that multiple M. bovis strains were circulating, with at least three founding introductions since the park inauguration in 1977. Using a previously sequenced dataset of 71 M. bovis genomes from cattle, we found no recent transmission events between nearby farms and the park based on WGS. Lastly, by discussing socio-economic and environmental factors escaping current regulatory gaps that were determinant of this outbreak, we pledge for the development of a plan to report and control bTB in wildlife in Brazil.

Genome Sequences of Mycobacterium tuberculosis Biovar bovis Strains Ravenel and 10-7428.

ABSTRACTWe report the draft genomes of two Mycobacterium tuberculosis biovar bovis strains. Strain Ravenel was isolated in the 1900s and has been shown to be attenuated in cattle. Strain 10-7428 is considered highly pathogenic in cattle and was isolated from a bovine tuberculosis outbreak.

Early Detection of Mycobacterium avium subsp. paratuberculosis Infected Cattle: Use of Experimental Johnins and Innovative Interferon-Gamma Test Interpretative Criteria.

Paratuberculosis (PTB), also known as Johne's disease, is a chronic proliferative enteritis of ruminants caused by Mycobacterium avium subsp.paratuberculosis (MAP). To date, PTB diagnosis, based on serology, fecal culture, and real-time polymerase chain reaction, has identified animals in advanced stages of infection. To detect MAP infection in animals earlier, the interferon-gamma (IFN-γ) test may be applied. This assay detects cytokines produced by T-lymphocytes of infected subjects after stimulation with purified protein derivatives (PPDs), extracted from Mycobacterium bovis (MB) and from M. avium (MA). The study involved three bovine herds: one PTB-infected herd, one PTB-free herd, and one with an outbreak of bovine tuberculosis. The IFN-γ test was performed on 235 animals, using bovine PPD (PPDB), avian PPD (PPDA), and three experimental PPD Johnins (PPDJs) extracted from a synthetic liquid medium culture of MAP (PPDJ A, B, and C), to assess early MAP detection and avoid false reactions to MB. Furthermore, IFN-γ results were evaluated using 12 interpretative criteria (ICs), based on the differences and ratio between PPD optical density (OD) and IFN-γ basal OD values after lymphocytic stimulation. IC accuracy was expressed as area under the receiver operating characteristic curve. Through a longitudinal study, PPDJs proved to be specific and sensitive in the detection of MAP-infected animals. Among the evaluated ICs, six showed the best performance in terms of accuracy (p < 0.0001), highlighting PTB subclinical infections. In particular, the two best criteria reached sensitivity values of 100% [confidence interval (CI) 95%, 94.1–100%] with a specificity of 91.8% (CI 95%, 81.9–97.3%) and sensitivity levels of 80.6% (CI 95%, 69.1–89.2%) with a specificity of 100% (CI 95%, 94.1–100%). Thus, the IFN-γ assay proved to be a useful diagnostic tool to identify early subclinical MAP-infected animals, in order to manage infected cattle or those exposed to MAP and to monitor younger calves within a herd. Furthermore, the IFN-γ test can be considered an additional test to avoid the introduction of MAP-infected animals, especially in herds where disease has already been eradicated and preservation of the health status is required to maintain the PTB certification level.

Cost-effectiveness of two different protocols for animal tracing investigations of bovine tuberculosis outbreaks in France

In the French bovine tuberculosis (bTB) surveillance program, tracing-on and back investigations have a major importance as, in 2016, they represented about 21 % of the detected outbreaks. Building on our previous work on the other surveillance system components (Poirier et al., 2019), we evaluated for the first time the sensitivity and the cost of the two existing protocols of bTB’s tracing-on investigations trough scenario tree modelling with a stochastic approach. We used French databases (national database for bovine identification and database recording all bTB surveillance and control results) and direct and indirect costs collected in a previous study. These assessments allowed us to calculate the cost-effectiveness index (cost/sensitivity) of each tracing-on protocol. In the first protocol (trace-and-cull protocol), the animal(s) linking the farm to an outbreak are systematically culled for bacteriology, PCR and histology testing. In the second protocol (trace-and-test protocol), the traced animal is culled only if it had non-negative result to an intradermal cervical comparative tuberculin test (ICCT). We estimated herd sensitivity of the two tracing-on protocols for 12 herd types defined by their production type, size and herd turnover. For the trace-and-cull protocol, mean herd sensitivity was estimated between 67.3 % [66.8–67.7]CI95 % and 89.2 % [88.7–89.7]CI95 % and between 51.2 % [50.8–51.5]CI95 % and 73.1 % [72.6–73.6]CI95 % for the trace-and-test protocol, depending on herd type. The trace-and-cull protocol was between 278 €/herd and 717 €/herd more expensive than the trace-and-test protocol, depending on herd type. Regardless of herd type, the trace-and-cull protocol had the smaller cost/sensitivity ratio and was therefore the most cost-effective protocol. That work showed that systematically culling traced animals to perform bacteriology and PCR on them (trace-and-cull protocol) is associated with a better herd sensitivity and is more cost-effective for all herd types. That is consistent with French veterinary authorities’ recommendations but does not account for sociological aspects such as the bond between the farmer and his animals. Yet, cost-effectiveness difference was minor in small dairy and beef herds with a low turnover, suggesting the protocol could be chosen depending on the epidemiological context in those herds.

Infection of Wildlife by Mycobacterium bovis in France Assessment Through a National Surveillance System, Sylvatub

Mycobacterium bovis infection was first described in free-ranging wildlife in France in 2001, with subsequent detection in hunter-harvested ungulates and badgers in areas where outbreaks of bovine tuberculosis (TB) were also detected in cattle. Increasing concerns regarding TB in wildlife led the French General Directorate for Food (DGAL) and the main institutions involved in animal health and wildlife management, to establish a national surveillance system for TB in free-ranging wildlife. This surveillance system is known as “Sylvatub.” The system coordinates the activities of various national and local partners. The main goal of Sylvatub is to detect and monitor M. bovis infection in wildlife through a combination of passive and active surveillance protocols adapted to the estimated risk level in each area of the country. Event-base surveillance relies on M. bovis identification (molecular detection) (i) in gross lesions detected in hunter-harvested ungulates, (ii) in ungulates that are found dead or dying, and (iii) in road-killed badgers. Additional targeted surveillance in badgers, wild boars and red deer is implemented on samples from trapped or hunted animals in at-risk areas. With the exception of one unexplained case in a wild boar, M. bovis infection in free-living wildlife has always been detected in the vicinity of cattle TB outbreaks with the same genotype of the infectious M. bovis strains. Since 2012, M. bovis was actively monitored in these infected areas and detected mainly in badgers and wild boars with apparent infection rates of 4.57–5.14% and 2.37–3.04%, respectively depending of the diagnostic test used (culture or PCR), the period and according to areas. Sporadic infection has also been detected in red deer and roe deer. This surveillance has demonstrated that M. bovis infection, in different areas of France, involves a multi-host system including cattle and wildlife. However, infection rates are lower than those observed in badgers in the United Kingdom or in wild boars in Spain.

Investigation of bovine tuberculosis outbreaks by using a trace-back system and molecular typing in Korean Hanwoo beef cattle.

Bovine tuberculosis is a chronic contagious disease responsible for major agricultural economic losses. Abattoir monitoring and trace-back systems are an appropriate method to control bovine tuberculosis, particularly in beef cattle. In the present study, a trace-back system was applied to bovine tuberculosis cases in Korean native Hanwoo beef cattle. Bovine tuberculosis was detected in three index beef cattle during abattoir monitoring in Jeonbuk Province, Korea, and the original herds were traced back from each index cow. All cattle in each original herd were subjected to tuberculin skin test. The positive rates in the tuberculin skin test were 64.6% (62 of 96), 4.8% (2 of 42), and 8.1% (3 of 37) at farms A, B, and C, respectively. On post-mortem examination of 56 tuberculin-positive cattle, 62% had granulomatous lesions, and Mycobacterium bovis was cultured from 40 (71.4%) of the cattle. Molecular typing by spoligotyping and the mycobacterial interspersed repetitive unit-variable-number tandem repeat assay revealed the genotype of the M. bovis strains from the index cattle were same as the M. bovis genotype in each original herd. The results suggest that tracing back from index cattle to the original herd is an effective method to control bovine tuberculosis in beef cattle.

Genotypes of Mycobacterium bovis strains isolated from domestic animals and wildlife in Canada in 1985–2015

Two internationally recognised and standardised genotyping methods, mycobacterial interspersed repetitive unit and variable number tandem repeat analysis (MIRU-VNTR) and spoligotyping, were applied to characterise genetic variations among 137 Mycobacterium bovis isolates recovered from Canadian domestic and wild animals during 1985–2015. Spoligotyping generated seven types that were discriminated further into12 MIRU-VNTR types. The discriminatory power indexes were estimated as 0.71 and 0.77 for spoligotyping and MIRU-VNTR typing approaches, respectively. In total, 6 prominent clusters of isolates were observed by the genotyping schemes. Four genotype clusters were exclusively observed in farmed animals. Three of these four clusters were affiliated with localised tuberculosis outbreaks, and each cluster corresponded to a single specific spoligotype (SB0140, SB0673, and SB1069) and a MIRU-VNTR profile. The fourth genotype cluster, with spoligotype SB0265 which segregated into two MIRU-VNTR types, was associated with bovine tuberculosis outbreaks in several farms across Canada during 1990–2002. Two genotype clusters of M. bovis stains were associated with wildlife reservoirs: a spoligotype SB0130 with 3 unique MIRU-VNTR profiles were observed in wood bison in Wood Buffalo National Park, and unique spoligotypes SB1070 and 1071 represented by four MIRU-VNTR profiles were recovered from cervidae species in and around the Riding Mountain National Park of Manitoba. Genotyping data confirmed M. bovis transmission between wildlife and livestock in Manitoba in 1990–2008.Overall, notwithstanding the low level of genetic diversity of Canadian M. bovis strains, the spoligotyping and MIRU-VNTR typing were useful tools in monitoring transmission of endemic strains and defining new introductions to Canada. The majority of genotypes were most likely introduced into domestic animals through live animal trade, and subsequently eliminated as a result of bovine tuberculosis outbreak investigation and eradication activities.

Patterns and processes of Mycobacterium bovis evolution revealed by phylogenomic analyses.

Mycobacterium bovis is an important animal pathogen worldwide that parasitizes wild and domesticated vertebrate livestock as well as humans. A comparison of the five M. bovis complete genomes from the United Kingdom, South Korea, Brazil, and the United States revealed four novel large-scale structural variations of at least 2,000 bp. A comparative phylogenomic study including 2,483 core genes of 38 taxa from eight countries showed conflicting phylogenetic signal among sites. By minimizing this effect, we obtained a tree that better agrees with sampling locality. Results supported a relatively basal position of African strains (all isolated from Homo sapiens), confirming that Africa was an important region for early diversification and that humans were one of the earliest hosts. Selection analyses revealed that functional categories such as “Lipid transport and metabolism,” “Cell cycle control, cell division, chromosome partitioning” and “Cell motility” were significant for the evolution of the group, besides other categories previously described, showing importance of genes associated with virulence and cholesterol metabolism in the evolution of M. bovis. PE/PPE genes, many of which are known to be associated with virulence, were major targets for large-scale polymorphisms, homologous recombination, and positive selection, evincing for the first time a plethora of evolutionary forces possibly contributing to differential adaptability in M. bovis. By assuming different priors, US strains originated and started to diversify around 150–5,210 ya. By further analyzing the largest set of US genomes to date (76 in total), obtained from 14 host species, we detected that hosts were not clustered in clades (except for a few cases), with some faster-evolving strains being detected, suggesting fast and ongoing reinfections across host species, and therefore, the possibility of new bovine tuberculosis outbreaks.

Epidemiological investigation of bovine tuberculosis outbreaks in Uruguay (2011–2013)

Bovine tuberculosis (bTB) is a chronic disease of cattle caused by infection with the Mycobacterium bovis. While bTB prevalence in Uruguay has been low (<11 outbreaks/year) for the past 50 years as a consequence of a national control program, annual incidence increased in 2011 through 2013–15, 26 and 16 infected herds each year, raising concerns from livestock stakeholders and the government. The goal of this study was to assess the spatial dynamics of bTB in Uruguay from 2011 to 2013 and the association between bTB and potential demographic and movement risk factors at the herd level using data provided by the Uruguayan Ministry of Livestock, Agriculture, and Fisheries. Clustering of incident outbreaks was assessed using the Cuzick-Edwards’ test and the Bernoulli model of the spatial scan statistic, and a conditional multivariable logistic regression model was used to assess risk factors associated with bTB in a subset of Uruguayan dairy farms. Significant (P<0.05) global clustering was detected in 2012, while high-risk local clusters were detected in southwestern (2011, 2012, 2013), northwestern (2012), and southeastern (2012) Uruguay. Increased risk of bTB in different regions of Uruguay suggests a potential role of animal movements in disease dissemination. Larger herds, higher numbers of animals purchased, and incoming steers to the farm were associated with increased odds of breaking with bTB, in agreement with previous studies but also suggesting other additional sources of risk. These results will contribute to enhanced effectiveness of bTB control programs in Uruguay with the ultimate objective of preventing or mitigating the impact of the disease in the human and animal populations of the country.

Determination of the Seasonality of Bovine Tuberculosis Disease from the Risk Based Disease Management

This study is among major epidemics in the world and Turkey is conducted to evaluate the seasonality of the risk factors of the disease bovine tuberculosis. The seasonal distribution of Turkey’s outbreak of bovine tuberculosis in the 2005-2014 year was investigated in this study. Office International des Epizooties outbreak data was used to determine Turkey’s monthly bovine tuberculosis outbreak data at the provincial level for this evaluation. Turkey's 81 provinces, seven geographic regions, and 12-month outbreak data are evaluated. The distribution of the four seasons of the outbreak to the coast and inland are analyzed for the determined seasonality of the disease. In the study, it was found that Turkey reached the highest number of outbreaks of the disease throughout the summer at a rate of 29.44%. In the study, the risk of bovine tuberculosis disease, diseases of the seasonality of the summer months when the investigation come to the fore, has been carefully assessed in terms of planning for disease control measures. As a result, reveals how it should be used in the identification of disease-specific risk that results obtained in the fight against the disease in this study and the importance of the fight against the disease. Taking control of the disease and timely measures for the disease will contribute to the reduction of costs related to the disease.

Genetic profiles of Mycobacterium bovis from a cattle herd in southernmost Brazil

Mycobacterium bovis is the agent of bovine tuberculosis, a disease endemic to all Brazilian states. Molecular typing techniques help to stratify and refine data, providing information that facilitates epidemiological research. In this study, MIRU-VNTR, targeting 24 loci, was employed to identify and characterize the genetic groups of M. bovis isolates obtained from an outbreak of bovine tuberculosis. Eighteen acid-fast bacilli isolates, obtained from bovine tissue samples, and reactive to the comparative cervical tuberculin test, were identified as species of the M. tuberculosis complex, and were genotyped by MIRU-VNTR with 24 primer pairs. Genotyping revealed three genetic profiles comprising one with 15 isolates (83.3%), one with two isolates (11.1%), and one profile with one unique isolate (5.6%). This distinction was achieved with the MIRU 31 primer, which resulted in clustering of two isolates into the same profile, and ETR A, B, and C, which discriminated the isolate with a unique profile. The occurrence of clustered isolates is indicative of recent transmission, whereas isolates with a unique profile suggest reactivation of latent infection. The presence of different M. bovis genotypes in the same herd suggests movement of infected animals or different sources of intra-herd infection. Use of the MIRU-VNTR molecular epidemiology technique in M. bovis isolates obtained from an outbreak of bovine tuberculosis in Rio Grande do Sul state demonstrated the genetic diversity of circulating strains, despite the presence of a predominant group.

LIMITED ANTIBODY EVIDENCE OF EXPOSURE TO MYCOBACTERIUM BOVIS IN FERAL SWINE (SUS SCROFA) IN THE USA.

Bovine tuberculosis is a chronic disease of cattle ( Bos taurus ) caused by the bacterium Mycobacterium bovis . Efforts have been made in the US to eradicate the disease in cattle, but spillover into wildlife and subsequent spillback have impeded progress in some states. In particular, infection in white-tailed deer ( Odocoileus virginianus ) has been followed by infection in cattle in some Midwestern states. Infection has also been documented in feral swine ( Sus scrofa ) on the Hawaiian island of Molokai and in various European countries, but no large-scale survey of antibody exposure to the bacteria has been conducted in feral swine in the US. We tested 488 sera from feral swine collected near previously documented outbreaks of bovine tuberculosis in cattle and captive cervids, in addition to 2,237 feral swine sera collected across the US from 1 October 2013 to 30 September 2014. While all but one of the samples were antibody negative, the results are important for establishing baseline negative data since feral swine are capable reservoirs and could be implicated in future outbreaks of the disease.

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

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

Herd outbreak of bovine tuberculosis illustrates that route of infection correlates with anatomic distribution of lesions in cattle and cats

An outbreak of bovine tuberculosis (TB) in a Michigan dairy herd resulted in quarantine, depopulation, pathology, and epidemiologic investigations. This herd, compared to other TB-infected herds in Michigan, was unusual in the long-term feeding of waste milk to its replacement calves. The herd had 80 cattle with positive results on caudal fold test or gamma interferon testing, which were reclassified as suspects because the herd had never been known to be tuberculous previously. Autopsy revealed striking variation in the anatomic distribution of gross anatomic lesions, microscopic lesions, and culture-positive lymph nodes between the adult cattle, the calves, and the domestic cats present on the farm. Adult cattle had lesions and culture-positive lymph nodes predominantly within the thoracic lymph nodes, whereas cats had 50% of their lesions and culture-positive lymph nodes in their abdomens, and 50% of positive calves had culture-positive lymph nodes in their abdomens. This difference in anatomic distribution correlated with the likely routes of infection, which are believed to be by direct airborne transmission in adult cattle and indirect ingestion of contaminated milk in both calves and cats. Although TB literature over the past 100-plus years states that the route of infection may manifest itself in differences in lesion anatomic distribution, our team has been working with TB for over 20 years, and we have never encountered such striking variation between different groups of animals on the same farm.

Descriptive Epidemiology and Whole Genome Sequencing Analysis for an Outbreak of Bovine Tuberculosis in Beef Cattle and White-Tailed Deer in Northwestern Minnesota.

Bovine tuberculosis (bTB) was discovered in a Minnesota cow through routine slaughter surveillance in 2005 and the resulting epidemiological investigation led to the discovery of infection in both cattle and white-tailed deer in the state. From 2005 through 2009, a total of 12 beef cattle herds and 27 free-ranging white-tailed deer (Odocoileus virginianus) were found infected in a small geographic region of northwestern Minnesota. Genotyping of isolates determined both cattle and deer shared the same strain of bTB, and it was similar to types found in cattle in the southwestern United States and Mexico. Whole genomic sequencing confirmed the introduction of this infection into Minnesota was recent, with little genetic divergence. Aggressive surveillance and management efforts in both cattle and deer continued from 2010–2012; no additional infections were discovered. Over 10,000 deer were tested and 705 whole herd cattle tests performed in the investigation of this outbreak.

Mycobacterium bovis in Panama, 2013.

Panama remains free of zoonotic tuberculosis caused by Mycobacterium bovis. However, DNA fingerprinting of 7 M. bovis isolates from a 2013 bovine tuberculosis outbreak indicated minimal homology with strains previously circulating in Panama. M. bovis dispersion into Panama highlights the need for enhanced genotype testing to track zoonotic infections.

Comparison of Tuberculin Skin Test, IFN-γ Assay, Real Time PCR and Lateral Flow Rapid Test in Diagnosis of Field Outbreaks of Bovine Tuberculosis

Bovine tuberculosis is an important zoonotic disease transmitted by direct contact, respiratory pathway, ingestion of unpasteurised milk and milk product, raw or undercooked meat. Tuberculosis can be difficult to diagnose based only on the clinical signs. Tuberculosis is usually diagnosed in the field with the tuberculin skin test. Sputum and other body fluids may be collected for microbiological examination. Polymerase chain reaction (PCR) methods have also been described. Diagnostic blood tests include the lymphocyte proliferation assay, the interferon gamma (IFN-γ) assay, and enzyme-linked immunosorbent assays (ELISA). In this study a total of 50 animals were tested by using tuberculin skin test (TST), lateral flow rapid test, IFN-γ assay and real time PCR. The animals were selected randomly among 178 cattle in dairy farms with the aged between 3-5 years and suspected of having tuberculosis. Forty five cattle were positive out of 50 for TST while 31 for reactive by the IFN-γ assay and 28 for rapid test and 9 for real time PCR. The purpose behind such variable as age was to compare sensitivity of tuberculin skin test, the IFN-γ assay and TB lateral flow rapid test and real time PCR examination for the diagnosis of field outbreaks of bovine tuberculosis in Turkey.