Tuberculin Research Articles

Frequency of Latent Tuberculosis Infection in Patients with Type 2 Diabetes referred to Shahid Rahimi Hospital in Khorramabad City with Tuberculin Skin Test in 2018-2020

Introduction: Tuberculosis is the leading cause of death from infectious diseases worldwide. Diabetes has been suggested as an important risk factor for tuberculosis. To date, few studies have examined the association between diabetes and tuberculosis. In this study, the prevalence of latent tuberculosis in diabetic patients was investigated.
 Methods: In this study, 195 patients with type 2 diabetes were studied in a cross-sectional study to diagnose latent tuberculosis infection with a tuberculin skin test. Individuals with symptoms of active tuberculosis were excluded from the study, and individuals with a positive tuberculin test were evaluated for active tuberculosis by chest x-ray. For analyzing the data, SPSS software version 16 was run, a t-test was used to analyze quantitative variables, and for qualitative variables, Chi-square was applied. The significance level of 0.05 was considered for all the results.
 Results: Out of 195 diabetic patients, 115 patients were referred for tuberculin test results. 43 out of 115 patients (37.39%) had an induration diameter greater than or equal to 5 mm, 29 patients (25.21%) had an induration diameter greater than or equal to 8 mm, and 3 patients (2.61%) had an induration diameter greater than or equal to 10 mm (Positive tuberculin test) (p>0.05).
 Conclusion: False tuberculin skin test results can hide the true prevalence of latent tuberculosis infection. The sensitivity of the tuberculin test decreases in immunocompromised patients and leads to limitations in assessing the prevalence of latent tuberculosis infection. Although not enough information was available in this study to establish a significant association between diabetes and latent tuberculosis infection, further studies will help to investigate this association.

Defined Antigen Skin Test for Bovine Tuberculosis Retains Specificity on Revaccination With Bacillus Calmette-Guérin.

The Bacillus Calmette–Guérin (BCG) vaccination provides partial protection against, and reduces severity of pathological lesions associated with bovine tuberculosis (bTB) in cattle. Accumulating evidence also suggests that revaccination with BCG may be needed to enhance the duration of immune protection. Since BCG vaccine cross-reacts with traditional tuberculin-based diagnostic tests, a peptide-based defined antigen skin test (DST) comprising of ESAT-6, CFP-10, and Rv3615c to detect the infected among the BCG-vaccinated animals (DIVA) was recently described. The DST reliably identifies bTB-infected animals in experimental challenge models and in natural infection settings, and differentiated these from animals immunized with a single dose of BCG in both skin tests and interferon-gamma release assay (IGRA). The current investigation sought to assess the diagnostic specificity of DST in calves (Bos taurus ssp. taurus × B. t. ssp. indicus; n = 15) revaccinated with BCG 6 months after primary immunization. The results show that none of the 15 BCG-revaccinated calves exhibited a delayed hypersensitivity response when skin tested with DST 61 days post-revaccination, suggesting 100% diagnostic specificity (one-tailed lower 95% CI: 82). In contrast, 8 of 15 (diagnostic specificity = 47%; 95% CI: 21, 73) BCG-revaccinated calves were positive per the single cervical tuberculin (SCT) test using bovine tuberculin. Together, these results show that the DST retains its specificity even after revaccination with BCG and confirms the potential for implementation of BCG-based interventions in settings where test-and-slaughter are not economically or culturally feasible.

Tuberculosis pulmonar

Tuberculosis is an infectious disease caused by the Mycobacterium tuberculosis microorganism. It is one of the most prevalent infections both in our country and worldwide. Following exposure to the mycobacterium, primary infection occurs in the form of infiltrates and adenopathy followed by a disseminated latent infection phase. In some patients, tuberculosis reactivation can occur from a latent infection. Diagnosis is based on determining the presence of latent tuberculosis by means of a tuberculin test; the release of interferon gamma in the blood (IGRA); or the presence of active tuberculosis through the detection of the microorganism on a sputum smear test, culture, or via molecular techniques. Treatment must be prolonged —at least four or six months— and can be extended in cases of drug resistance. It usually requires a combination of first- and second-line pharmaceuticals, depending on resistance, that are structured into an intensive phase and a later continuation phase.

Prevalence of Bovine Tuberculosis among Cattle and Buffaloes in the Central Province of Sri Lanka

The Bovine tuberculosis (bTB) is a chronic disease condition in dairy cattle and a proven global zoonosis. This study was designed to identify the prevalence of bTB in dairy cattle and buffaloes in the Central Province (CP) of Sri Lanka. Single Intradermal Comparative Cervical Tuberculin (SICCT) test was performed in 20 farms (n=616 cattle and buffaloes) in three districts (NuwaraEliya; NE, Kandy; KN, and Matale; MT) in the CP. Out of the SICCT positive samples, randomly selected serum samples (n=33) of eight farms were subjected to the rapid antibody (Ab) test for further confirmation. Results were evaluated for different risk factors; age, sex, parity, body condition score (BCS), breed, herd origin, reproductive status, herd size, type of management, and duration of farm establishment. The prevalence of bTB among individual cattle and buffaloes was 22% with a 50% herd-level prevalence. In NE and KN, 34% and 19% of individuals showed positive reactions for SICCT, respectively, while all the individuals in MT were negative. There were significant statistical associations (P<0.05) were observed with the prevalence of bTB and BCS, breed, herd origin, and reproductive status; however, age, sex, parity, herd size, type of management, and duration of farm establishment were not statistically significant (P>0.05) with the prevalence of bTB.The conclusion is that, based on the SICCT test, the estimated prevalence of bTB in cattle and buffaloes in the central province of Sri Lanka is relatively high (>20%). The SICCT test could be recommended for the screening of the bTB in cattle and buffaloes in all regions of Sri Lanka to assess the island-wide prevalence of bTB, as this disease carries the risk of transmitting to humans and other susceptible animal species.

Utility of the Intradermal Skin Test in a Test-and-Cull Approach to Control Bovine Tuberculosis: A Pilot Study in Ethiopia.

Bovine tuberculosis (bTB) is one of the top three, high-priority, livestock diseases in Ethiopia and hence, the need for evaluation of potential control strategies is critical. Here, we applied the test-and-segregate followed by cull strategy for the control of bTB in the intensive Alage dairy farm in Ethiopia. All cattle reared on this farm were repeatedly skin tested using the Comparative Cervical Tuberculin (CCT) test for a total of five times between 2015 and 2021. During the first (October 2015) and second (March 2017) rounds of testing, all reactor animals (>4 mm) were culled, while those that were deemed as inconclusive (1–4 mm) were segregated and retested. At retest, animals with CCT >2 mm were removed from the herd. In the third (December 2017) and fourth (June 2018) rounds of tuberculin testing, a more stringent approach was taken wherein all reactors per the severe mode of CCT test interpretation (>2 mm) were culled. A final herd status check was performed in May 2021. In summary, the number of CCT positives (>4 mm) in the farm dropped from 23.1% (31/134) in October 2015 to 0% in December 2017 and remained 0% until May 2021. In contrast, the number of Single Cervical Tuberculin (SCT) test positives (≥4 mm) increased from 1.8 to 9.5% (from 2017 to 2021), indicating that CCT test might not be sufficient to effectively clear the herd of bTB. However, a more stringent approach would result in a drastic increase in the number of false positives. The total cost of the bTB control effort in this farm holding 134–200 cattle at any given time was conservatively estimated to be ~US$48,000. This, together with the need for culling an unacceptably high number of animals based on skin test status, makes the test-and-cull strategy impractical for nationwide implementation in Ethiopia and other low- and middle-income countries (LMICs) where the infection is endemic. Hence, there is an increased emphasis on the need to explore alternate, affordable measures such as vaccination alongside accurate diagnostics to help control bTB in endemic settings.

A Multi-Center, Randomised, Double-Blind, Placebo-Controlled Phase III Clinical Trial Evaluating the Impact of BCG Re-Vaccination on the Incidence and Severity of SARS-CoV-2 Infections among Symptomatic Healthcare Professionals during the COVID-19 Pandemic in Poland-First Results.

Tuberculosis vaccines (Bacillus Calmette-Guérin, BCG) were introduced 100 years ago and are still recommended by the World Health Organization to prevent the disease. Studies have shown that BCG vaccination can stimulate non-specific immune responses and reduce the incidence of certain diseases. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, it was hypothesised that the incidence of COVID-19 was lower in countries with BCG prevention. In an attempt to verify this thesis, we conducted a multicenter, randomised, double-blind, placebo-controlled study on a group of 695 health care workers aged 25 years and over in Poland. All participants in the study had a tuberculin test, after which those who were negative were randomised (1:1) and received either the BCG- or placebo vaccine. From then on, these people were subjected to three months of observation for the occurrence of COVID-19 symptoms. The statistical analysis did not reveal any significant correlation between the frequency of incidents suspected of COVID-19 and BCG-10 vaccination, the result of the tuberculin test and the number of scars. The only statistically significant feature was the type of medical profession—nurses became infected more often than doctors or other medical workers (p = 0.02). The results differ from similar trials in other countries. Perhaps this is due to the lack of an unvaccinated control group. The impact of BCG vaccination on the course of COVID-19 requires further research.

Factors affecting the performance of P22 ELISA for the diagnosis of caprine tuberculosis in milk samples

Caprine tuberculosis (TB) is a zoonosis caused by members of the Mycobacterium tuberculosis complex (MTBC). Caprine TB eradication programmes are based mainly on intradermal tuberculin tests and slaughterhouse surveillance. However, the use of serological test has been extended as a potential diagnostic tool in goats through the use of serum, plasma, or even milk samples. Milk production and the antibodies (Ab) present in milk can vary depending on several circumstances. In the present study, different factors that may affect the performance of humoral TB diagnosis were analysed using goat milk samples: 1) lactation stage, 2) a recent previous skin test (booster effect) and 3) the effect of freeze-thaw cycles on milk samples preserved with azidiol. TB-infected animals (n = 44) were selected to evaluate the evolution of the Ab levels during the 6-month lactation period, along with its potential effect on the P22 ELISA results. In general, no significant changes (p = 0.079) were observed throughout the study as regards Ab levels in milk samples between consecutive analysis although the reactivity to P22 ELISA decreased when samplings were performed at the last two months of the lactation. Regarding the booster effect, the quantitative results showed a significant variation (p < 0.001) for both milk and serum samples when serological tests were carried out 15 days after the skin test. Finally, there were no significant differences (p = 0.99) in the P22 ELISA results when using milk samples preserved with azidiol that had undergone freeze-thaw cycles.

Evaluating the risk of bovine tuberculosis posed by standard inconclusive reactors identified at backward-traced herd tests in Northern Ireland that disclosed no reactors

Bovine tuberculosis is a notifiable disease in Northern Ireland with the national eradication programme of compulsory testing and slaughter of reactor animals costing approximately £40 million per year. Backward tracing, known as Backward Check Tests (BCTs), of reactor animals is used to identify previous herds where the bTB positive animal has resided. The aim of this study was to quantify the bovine tuberculosis (bTB) risk posed by inconclusive reactors (ICs) at BCTs at both the individual animal and the herd level. ICs to the Comparative Intradermal Tuberculin Test (CITT) at a BCT, in which no reactors were found, were matched with CITT negative animals, based on age, sex, test ID and follow up period, in Northern Ireland between 1st January 2008 and 31st December 2017 (inclusive). A retrospective matched cohort study design was used with the outcome of interest being the bTB status of each animal and subsequent bTB herd breakdowns. After adjusting for herd size, IC animals at a BCT had 16 times the odds (95% confidence interval: 7.75 to 38.28, p < 0.001) of becoming bTB positive compared to CITT negative animals. The percentage population attributable risk was 0.0001%. The majority 75% (n = 71) of ICs that became bTB positive were identified at the 42 day retest. Of those that were not disclosed at the 42 day retest (n = 24), almost a third (29%) had moved to an unrestricted herd. However, after adjusting for herd size and type, herds that had ICs only identified at a BCT did not have an increased odds of a subsequent bTB herd breakdown compared to herds that had a CITT negative BCT. Given the increased risk posed by ICs at a BCT, it may be justifiable to remove them from the herd immediately or place them under lifetime movement restrictions to the herd where they were detected. However, further action regarding the herd of origin does not appear to be justified.

Tuberculin test errors and its effect on detection of bovine tuberculosis

Bovine tuberculosis is an endemic disease in Egypt, a notable gap exists between limited cases identified by single intradermal tuberculin test performed through the national control program and higher detected cases at abattoirs. Therefore, this study aimed to investigate epidemiological situation and causes of the previously mentioned gap in Middle-Delta Region. A total of 25 emergency-slaughtered animals of unknown tuberculosis-status were investigated by cocktail-antigens ELISA and post-mortem examination. Five visible tuberculous-lesion cases were detected and confirmed by PCR, ELISA was sensitive and predictive of the existence of tuberculous-lesions; 4(80%) out of 5 visible-lesion cases were seropositive. True prevalence among the slaughtered animals was 27%. In addition, tuberculin-testing of 400 animals during the national control program was evaluated, many technical and procedural errors were detected, and all animals were negative.Out of them, 55 animals were tested by ELISA before the application of tuberculin test, 30 (54.5%) animals were seropositive. To confirm the effect of the reported errors on reliability of tuberculin test, reference serum of 20 tuberculosis-positive animals that were tested by standard-procedures tuberculin test and their status were confirmed by PCR after slaughtering, were tested by ELISA. A complete matching was evident, the 20 standard-tuberculin positive animals were all seropositive. In conclusion, bovine tuberculosis is endemic at high levels in the study area, reported errors of tuberculin test during national control program may be the cause for missing tuberculosis cases and not tuberculin test itself and finally, a further wide-scale funded study is required to discover the situation throughout Egypt.

Effect of the topical administration of corticosteroids and tuberculin pre-sensitisation on the diagnosis of tuberculosis in goats

BackgroundCaprine tuberculosis (TB) is a zoonosis caused by members of the Mycobacterium tuberculosis complex (MTBC). Caprine TB control and eradication programmes have traditionally been based on intradermal tuberculin tests and slaughterhouse surveillance. However, this strategy has limitations in terms of sensitivity and specificity. Different factors may affect the performance of the TB diagnostic tests used in goats and, subsequently, the detection of TB-infected animals. In the present study, the effect of two of the factors that may affect the performance of the techniques used to diagnose TB in goats, the topical administration of corticosteroids and a recent pre-sensitisation with tuberculin, was analysed.MethodsThe animals (n = 151) were distributed into three groups: (1) a group topically treated with corticosteroids 48 h after intradermal tuberculin tests (n = 53); (2) a group pre-sensitised with bovine and avian purified protein derivatives (PPDs) 3 days before the intradermal tuberculin test used for TB diagnosis (n = 48); and (3) a control group (n = 50). All the animals were tested using single and comparative intradermal tuberculin (SIT and CIT, respectively) tests, an interferon-gamma release assay (IGRA) and a P22 ELISA.ResultsThe number of SIT test reactors was significantly lower in the group treated with corticosteroids when compared to the pre-sensitised (p < 0.001) and control (p = 0.036) groups. In contrast, pre-sensitisation with bovine and avian PPDs did not cause a significant reduction in the number of SIT and CIT test reactors compared with the control group. In fact, a higher number of reactors was observed after the prior tuberculin injection in the pre-sensitised group (p > 0.05). No significant effect was observed on IGRA and P22 ELISA due to corticosteroids administration. Nevertheless, a previous PPD injection affected the IGRA performance in some groups.ConclusionsThe application of topical corticosteroid 24 h before reading the SIT and CIT tests can reduce the increase in skin fold thickness and subsequently significantly decrease the number of positive reactors. Corticosteroids used can be detected in hair samples. A previous pre-sensitisation with bovine and avian PPDs does not lead to a significant reduction in the number of intradermal tests reactors. These results are valuable in order to improve diagnosis of caprine TB and detect fraudulent activities in the context of eradication programs.

Epidemiology of Avian Tuberculosis in Selected Districts of Oromia Region, Ethiopia.

Avian tuberculosis is a growing public health concern and a significant impediment to socioeconomic development, especially in developing countries, where the risk of infection is high. The disease is predominantly caused by Mycobacterium avium belonging to serotypes 1, 2, 3, and 6 (genotypes IS901 and IS1245) and Mycobacterium genavense. It mostly occurs in older birds and immunocompromised individuals due to the greater opportunity for infection with age and host immunity. A cross-sectional study anticipated to generate epidemiological information on avian tuberculosis was carried out from November 2016 to June 2017 at highland areas of Gerar Jarso, Ada'a (midland), and Boset (lowland) districts of Oromia region, Ethiopia. Two hundred seventy-three village chickens comprising local breeds, exotic breeds, and crossbreeds of both sexes were used in the study. Single intradermal avian tuberculin test, postmortem inspection of positive reactors, mycobacteriological culturing, and histopathological examination were used to assess information on the epidemiology of the disease. Subsequently, avian tuberculin test revealed an overall apparent prevalence of 11.4% (31/273) and a specific prevalence of 6.8% (6/88) in the highland, 13.4% (13/97) in the midland, and 13.6% (12/88) in the lowland study districts. Besides, it signified a higher odd of exposure in crossbreeds and females as compared to locals and males. In addition, greater odd of exposure was observed in chickens at mid- and low altitudes as compared to those at the highland. Moreover, 40.9% (9/22) of positive reactor chickens sacrificed for necropsy showed gross pathological lesions. Similarly, histopathological examination revealed a granuloma characterized by central necrosis and peripheral mononuclear lymphocytes. Nevertheless, only 0.02% (2/120) of the cultured tissues had shown colonial growth up to 12 weeks of incubation, and both were seen on sodium pyruvate-enriched Lowenstein–Jensen medium slants. Generally, the study revealed an overall increment of the apparent prevalence of avian tuberculosis with decreasing altitude. Besides, it signified a relative breed and sex variation in the risk of acquiring the disease, with crossbreeds and female chickens having higher odds of exposure.

Evaluation of using comparative intradermal tuberculin test to diagnose bovine tuberculosis in dairy cattle in Taiwan.

The National Bovine Tuberculosis (bTB) Eradication Program for dairy cattle has been operating in Taiwan for many years and has allowed the prevalence of bTB to decrease gradually. However, 29% of intradermal tuberculin test (ITT)-positive dairy cows were later found to be TB negative based on necropsy, histopathological examination, and mycobacterial isolation results. Studies in Taiwan have indicated that Mycobacterium avium subsp. paratuberculosis (MAP) may lead to false-positive ITT. Due to the high prevalence (over 90%) of paratuberculosis (PTB) serum antibody among Taiwan's farms, comparative ITT (CITT) has been recommended to differentiate between bTB and PTB infections. In this study, we used ITT, CITT, and enzyme-linked immunosorbent assay (ELISA) to evaluate the prevalence of bTB from 2012 to 2018. We also used pathological and bacterial examination from ITT-positive dairy cows to evaluate CITT's diagnostic ability and adjust its cutoff point accordingly. After careful selection, 36 cows (including 31 cows from 11 ITT-positive farms and 5 from 2 ITT-negative farms) were examined by CITT. The cutoff point was adjusted using a receiver operating characteristic (ROC) analysis. Overall, our results identified the ITT-positive prevalence in Taiwan as 0.03-0.22%, and PTB-positive prevalence as 54.55-73.53%. The results of sensitivity, specificity, kappa, and ROC analyses have identified the optimal cutoff point for the CITT in Taiwan as ≥ 3mm. At this cutoff point value, the sensitivity and specificity were 62.5% and 96.43%, respectively. Our findings can be used to reduce the false-positive response rate caused by PTB cross-reaction and accelerate the eradication of bTB in Taiwan.

Pathogenesis of domestic pigs submitted to mycobacterial sensitizations previous to experimental infection with Mycobacterium bovis

Aim of study: To demonstrate the virulence of a Mycobacterium bovis local pig isolate in order to contribute to a better understanding of the pathological and immunological consequences of M. bovis infection in previous sensitized animals. Area of study: Buenos Aires, Argentina Material and methods: One group of ten pigs received two oral doses of killed M. bovis suspension and a comparative intradermal tuberculin test (CIT) (multiple sensitized) and then was infected with the M. bovis strain. Another group only received the CIT (single sensitized) and the infective dose. Humoral immune response was followed monthly, and gross pathology, histopathological and bacteriological analysis were performed at necropsy 100 days after infection. Main results: M. bovis oral infection induced lesions and allowed bacterial growth in most of the animals. Previous sensitization with killed M. bovis suspension slightly raised the intensity of the response, as the multiple sensitized group showed higher lesion scores and humoral response. Research highlights: Although the differences in lesion scores were not statistically significant, oral route infection after sensitization can modify the course of infections towards a fast development of lesions with a higher fibrotic component suggestive of increased resistance to infection in the right conditions.

Evaluation of effectiveness of mass screening for tuberculosis infection in children from 1 to 7 years old in Moscow

The objective: to evaluate effectiveness of mass screening for tuberculosis infection in children aged 1 to 7 years in different periods – before and after the use of tuberculosis recombinant allergen skin test (TRA) in primary health care as an additional diagnostic method.Subjects and Methods. The study was designed as continuous observational prospective-retrospective study. Two different periods were assessed: the first one was 2014-2016 when screening for tuberculosis infection was performed in all children from 1 to 17 years (inclusive) using Mantoux test with 2 TU PPD-L in pediatric primary health care, and then children suspected to have a positive reaction were referred to TB dispensary where they were examined with a skin test with TRA if necessary. The second period was from 2018 to 2020 when children of 1-7 years old were given Mantoux test and if tuberculosis infection was suspected, a skin test with TRA was done both in primary health care network and TB units. In the first 3 years, 1,864,137 children were examined and in the second 3 years, 2,078,800 children from 1 to 7 years old were examined.Results. Among children of 1-7 years old who were screened by two stages (initial Mantoux test, and then in those who had a positive reaction, the TRA test was used), only 10-12% of those referred to a phthisiologist were subject to dispensary follow-up. Thus, with the implementation of the new edict on screening for tuberculosis infection in children with two tests, this proportion has not changed compared to previous years, when screening was carried out only with one Mantoux test. The reason why almost 90% of the children who were referred to TB Dispensary were not subject to dispensary follow-up is the following: children who have had previous conversion of tuberculin tests, along with everyone else are again screened with Mantoux test despite being previously followed up by TB dispensary due to the primary infection.Recommendations:Currently, there is no division of Group VI into Subgroups A, B, C in the dispensary follow up grouping. Why should conversion of Mantoux test reaction from negative into positive not be considered an infection, and the increase in the reaction must be at least 6 mm.Since Order No. 124n of the Russian Ministry of Health allows testing with TRA in the primary health care in case of suspected infection, it is advisable to refer those who have already had this test to a phthisiologist.A child with conversion of Mantoux test should not be re-screened with Mantoux test but the TRA test should be used. If a positive reaction to the TRA test occurs for the first time, it should be considered as conversion of this test, and in this case the child should be examined by computed tomography (CT), and preventive therapy should be prescribed. If in subsequent years the TRA reaction increases by at least 6 mm after previous preventive therapy, the child should be re-referred for CT to rule out the development of active tuberculosis.

Blood monocyte subtypes in patients with pulmonary tuberculosis infection

Background and aim Monocytes are the primary target for Mycobacterium tuberculosis infection. Important alterations in the proportions of circulating monocyte subpopulations were found in patients with active tuberculosis (aTB). Our aim was to investigate the peripheral blood monocyte subsets in patients with active pulmonary tuberculosis (aPTB) and to evaluate their role in treatment response. Patients and methods A case–control study included 30 patients with aPTB and 30 healthy controls. Laboratory investigations include sputum examination, tuberculin test, and nucleic acid amplification test using GeneXpert MTB/RIF assay on sputum sample for patients only to confirm the diagnosis of aPTB. For all participants; complete blood count, erythrocyte-sedimentation rate, HIV antibodies, and flow cytometry analysis of peripheral blood monocyte subsets were done using surface markers CD14 phycoerythrin cyanin 7 and CD16 fluoroisothiocyanate for identification of monocyte subsets. Flow cytometry analysis was repeated 2 months after the start of treatment in aTB patients only. Results Classical monocytes were decreased while intermediate, and nonclassical monocytes were increased in aTB patients before treatment more than after 2 months of treatment and control group (P≤0.0001 for each). There was no significant difference in the three monocyte subsets between PTB patients after treatment and healthy controls. Also, the classical monocytes decreased while intermediate, and nonclassical monocytes increased in aTB patients with positive tuberculin test more than healthy controls with positive tuberculin test (P&lt;0.0001 for each). Conclusion The expansion of CD16+ monocytes was reversed after treatment with anti-TB drugs and could be used to follow up tuberculous patients for treatment effectiveness.

ELISA indreto como método complementar de diagnóstico da tuberculose bovina

ABSTRACT: Bovine tuberculosis is an economic and health problem, requiring precise diagnostic methods for its control and eradication. The aim of this study was to evaluate the performance of a commercial enzyme-linked immunosorbent assay (ELISA) test for the diagnosis of bovine tuberculosis. A total of 1,644 cattle from eight dairy herds were evaluated using the comparative cervical tuberculin test (CCTT). Three of the herds had no recent tuberculosis infection, and the other five had shown positive results in a previous tuberculin test. For the serological diagnosis of tuberculosis, a commercial ELISA antibody test kit for Mycobacterium bovis was used. Serum samples from 846 cattle from the eight herds were evaluated using ELISA for M. bovis. Animals that were positive based on either CCTT or ELISA for M. bovis or both were sent to slaughter. Samples of their lungs, livers, and lymph nodes were collected and stored under refrigeration for microbiological culture and subsequent confirmation by polymerase chain reaction. Samples from the same tissues were also fixed with 10% formaldehyde in bottles for histopathological examination and stained with hematoxylin and eosin (HE). Of the 1,644 cattle, 61 were considered positive and 65 inconclusive based on CCTT. Retesting of the inconclusive samples identified an additional 19 positive cases, totaling 80 (4.8%) CCTT-positive animals from five herds. ELISA for M. bovis identified 4.2% (36/846) positive cattle, of which 35 were considered negative and one inconclusive based on CCTT. Of the 36 positive cases identified by ELISA for M. bovis, 27 were euthanized, 11% (3/27) showed suggestive lesions of tuberculosis on macroscopic examination, and two were confirmed by histological, microbiological, and PCR methods. The weak association of ELISA for M. bovis with the results obtained by macroscopic, histological, and microbiological isolation indicates the fragility of ELISA performance in field conditions. Therefore, it is suggested that its use as a complementary method for herd sanitation be based on the local epidemiological situation.

Diagnosis of goat tuberculosis using tuberculinization and molecular techniques

Tuberculosis is an infectious, chronic, and worldwide disease. It has been known since the beginning of humanity and still negatively influences public health and livestock, especially, in Brazil, in the northeast. Etiologic agents are the mycobacteria of the Mycobacterium tuberculosis complex, which is the most important in mammals’ involvement. The state of Bahia has 68.7% of its territory located in the semiarid region and holds the largest goat herd in the country. Goat breeding is a social and economic activity that adds value to this region. Up to the present, data on goat tuberculosis is unknown in this state. Thus, this study seeks data on tuberculosis prevalence in goats in a semiarid region of Bahia by using the comparative tuberculin test and multiplex polymerase chain reaction (PCR). A total of 600 adult animals of both sexes were evaluated. A prevalence of 0.33% (2/600) and 33.33% (1/3) properties were found for positive animals. Each assessed property had a questionnaire to analyze the epidemiological data management and relevant aspects for the disease occurrence. To confirm the positive tuberculin test results, PCR was used to detect and identify the pathogenic mycobacteria involved in the infection. It is concluded that most of the properties performing goat breeding in the region show low technification levels and promote farming between different species. Low prevalence of the disease alerts preventive measures to avoid major proportion situations that could influence the goat breeding in the state.

PCR investigation of the vertical transmission of Mycobacterium bovis in Montbéliarde cattle in Gonbad, northeast of Iran

Bovine tuberculosis is an important global zoonosis. The causative agent of the disease is Mycobacterium bovis, belonging to the Mycobacterium tuberculosis complex. This study aimed to identify vertical transmission of Mycobacterium bovis in tuberculin positive pregnant dairy cows referred to the slaughterhouse and commercial sperm used to inseminate them in Gonbad, Gorgan province, Iran, by PCR assay. From March to September 2016, one thousand and seven hundred artificially inseminated cows were subjected to the tuberculin test; then, tuberculin positive cows were referred to the Gonbad slaughterhouse. Samples containing milk, lymph node, placenta, foetal abomasal fluid, and amniotic fluid were prepared from all affected cows and stored at -80 °C until analysis. Bacterial DNA was extracted from all specimens by a commercial kit. Detection was performed by amplifying pncATB gene using special primers via the polymerase chain reaction method. Results of tuberculin test revealed 144 positive cases (8.47%). PCR results for 48 milk samples, 120 biopsy samples, 63 samples of foetuses showed 9, 93 and 43 positive cases, respectively which all belonged to tuberculin positive samples. No positive sperm samples were identified. It was concluded that the infection rate with M. bovis in Montbéliarde cattle was high and also, that vertical transmission was not seen.

Overdiagnosis of Tuberculosis and Role of Tuberculin Test

Overdiagnosis of Tuberculosis and Role of Tuberculin Test

Molecular characterization of Mycobacterium bovis strains isolated from cattle and humans by spoligotyping and 24-locus MIRU-VNTR, and prevalence of positive IGRA in slaughterhouse workers in Southern Turkey.

Mycobacterium bovis is a zoonotic member of the Mycobacterium tuberculosis complex with a wide range of hosts, mainly cattle. Molecular epidemiological studies should be conducted to determine the transmission route, zoonotic risk factors, and phylogenetic relationships of M. bovis strains. Aims: This study aimed to characterize bovine and human M. bovis isolates by molecular methods. Molecular characterization and clonal relationship of strains isolated from tissue and organ samples of 76 cattle with positive tuberculin tests were collected from a slaughterhouse, and four M. bovis strains isolated from clinical materials of patients with suspected pulmonary TB isolates were analyzed using 24-locus MIRU-VNTR and spoligotyping methods. QuantiFERON-TB Gold Plus (QFT-Plus; Qiagen) was used to determine the prevalence of latent TB infection among 21 slaughterhouse personnel including 7 veterinarians, 12 butchers, 1 caretaker, and 1 veterinary technician. SB0288/SIT685 type was detected in both cattle and humans by the spoligotyping method. When evaluating MIRU-VNTR, the presence of a 100% compatible pattern between human and bovine isolates was not detected, but some human samples were found to be 91.6% similar to a bovine sample. In addition, 21 slaughterhouse workers were screened with the interferon gamma-released assay (IGRA) and a 23.8% positivity was detected. Clonal similarity was determined between the bovine and human isolates using the MIRU-VNTR and spoligotyping methods and IGRA positivity in the occupational group suggested that M. bovis might be associated with pulmonary tuberculosis in humans.