Single Intradermal Tuberculin Research Articles

Parallel testing increases detection of Mycobacterium bovis-infected African buffaloes (Syncerus caffer)

The diagnosis of Mycobacterium bovis (M. bovis) infection in African buffaloes (Syncerus caffer) relies on detection of the cell-mediated immune response to M. bovis antigens using the single comparative intradermal tuberculin test (SCITT) or interferon gamma release assays (IGRAs). The aim of the present study was to determine whether parallel testing with the SCITT and an IGRA increases the number of M. bovis-infected buffaloes detected by these assays. Culture-confirmed animals (n = 71) tested during routine bovine tuberculosis (bTB) control programmes in Hluhluwe iMfolozi Park and Madikwe Game Reserve in South Africa, were used in this study. Results from 35 buffaloes tested using the SCITT and three Bovigam® IGRAs (cohort A) and 36 buffaloes tested using the SCITT, standard Bovigam® IGRA and Qiagen Cattletype IGRA (cohort B) were analysed. The parallel use of the SCITT with selected IGRAs was able to identify all animals in both cohorts. These findings are in agreement with cattle studies supporting the use of the SCITT and IGRAs in parallel to identify the greatest number of M. bovis-infected animals. The suggested parallel testing algorithm should be strategically applied to maximize detection of M. bovis infection in bTB-positive buffalo herds.

The impact of the number of tuberculin skin test reactors and infection confirmation on the risk of future bovine tuberculosis incidents; a Northern Ireland perspective.

Currently policies enabling cattle herds to regain Official Tuberculosis Free (OTF) status after a bovine tuberculosis (bTB) herd incident vary between individual parts of the British Isles from requiring only one negative single comparative intradermal tuberculin test (SCITT) herd test when bTB infection is not confirmed to needing two consecutively negative SCITT herd tests after disclosure of two or more reactors, irrespective of bTB confirmation. This study used Kaplan-Meier curves and univariable and multivariable Cox Proportional Hazard models to evaluate the effect of the number of SCITT reactors and bTB confirmation on the risk of future bTB herd incident utilising data extracted from the national animal health database in Northern Ireland. Based on multivariable analyses the risk of a future bTB herd incident was positively associated with the number of SCITT reactors identified during the incident period (hazard ratio = 1.861 in incidents >5 SCITT reactors compared to incidents with only one SCITT reactor; P < 0.001), but not with bTB confirmation. These findings suggest that the probability of residual bTB infection in a herd increases with an increasing number of SCITT reactors disclosed during a bTB herd incident. It was concluded that bTB herd incidents with multiple SCITT reactors should be subjected to stricter control measures irrespective of bTB infection confirmation status.

Prevalence of Bovine Tuberculosis among Buffaloes Innorth Karnataka

The present study was undertaken to assess the prevalence of bovine tuberculosis among buffaloes in Belgaum, Dharwad and Bagalkote districts of North Karnataka, for a period of eight years (2002 to 2009). A total of 2184 buffaloes belonging to 30 organized farms were screened by single intradermal tuberculin test using bovine tuberculin Purified protein derivative. Overall prevalence of tuberculosis among buffaloes was found to be 0.96 per cent. Prevalence was higher in females (0.97%) than males (0.84%) and in Murrah (1.02 %) than Surthi (0.85 %). Analysis of the temporal pattern revealed a gradual declining trend over a period of eight years.

Evaluation of the use of a needle-free injection syringe as a cause of non-specific reactions in the intradermal tuberculin test used for the diagnosis of bovine tuberculosis

The objective of the study was to elucidate whether the use of the needle-free Dermojet syringe, which is based on a high pressure inoculation and is used to inject tuberculin in cattle in several countries, may, in itself, cause skin reactions that can be interpreted as positive reactions to the intradermal tests that are not, in fact, related to the real infection status of the animals.Forty-four cattle from an officially tuberculosis-free (OTF) herd were selected, and four single intradermal tuberculin (SIT) tests were performed on each animal, two on each side of the neck. Three different Dermojet (D1, D2 and D3) and one McLintock (M4) syringes were used to carry out sterile phosphate buffer saline (PBS) with 10% of glycerol and bovine PPD injections.No positive reactions to the SIT test were observed when using the D1-D3 syringes in the case of either bovine PPD or PBS. With regard to M4 (PBS), all the tests were negative when using a standard interpretation but three were positive in the case of the severe interpretation. Significant differences (p < 0.05) in the skin fold thickness measured were found only between certain Dermojet and McLintock syringes at certain inoculation sites. The results showed that the needle-free Dermojet syringe used for PPD intradermal testing in cattle did not cause significant reactions that could be misunderstood as positives.

Temporal analysis of the interference caused by paratuberculosis vaccination on the tuberculosis diagnostic tests in goats

Vaccination against paratuberculosis (PTB) in goats is a cost-effective control strategy, and is also effective as regards preventing the onset of clinical cases. However, it causes interference in the diagnostic tests used in the control of tuberculosis (TB). A group of 99 goats from a herd with no history of TB or PTB infection was vaccinated against PTB at seven months of age. They then underwent consecutive intradermal tests [single (SIT) and comparative (CIT) intradermal tuberculin tests), interferon-gamma release assays (IGRA) and two serological tests (p22_CE and DR-ELISA) every three months, until the interference disappeared. When using the SIT test, a variable number of positive reactors were observed at 3 months (T3; 32.3%, 95% CI 23.9–42.1), 6 months (T6; 11.5%, 95% CI 6.5–19.4), 9 months (T9; 6.4%, 95% CI 3.0–13.2) and 12 months (T12; 0%, 95% CI 0–4.0) post-vaccination. In contrast, the CIT test had a specificity (Sp) of 100% (95%, CI 96.0–100, regardless of the time post-vaccination. The IGRA also obtained high Sp values throughout the study period. No significant interference in the serological tests was recorded at T3 [p22_CE, Sp = 96% (95% CI 90.1–98.4) and DR-ELISA, Sp = 98% (95% CI 92.9–99.4)], although an increase in antibody titers was observed in the following herd testing events. In conclusion, the use of the SIT test causes the onset of false-positive reactors if applied before 12 months post-vaccination in a TB-free/PTB-vaccinated herd. Nevertheless, the CIT test and IGRA obtained high Sp values under these epidemiological circumstances. The serological tests were also highly specific in the case of PTB-vaccinated goats, although their Sp decreased significantly after several intradermal tests.

The use of serological tests in combination with the intradermal tuberculin test maximizes the detection of tuberculosis infected goats

The diagnosis of tuberculosis (TB) in goats is based mainly on the single and comparative intradermal tuberculin (SIT and CIT) tests and, exceptionally, on the interferon-gamma (IFN-γ) assay, however they are not perfect in terms of sensitivity and specificity. Nevertheless, various serological assays that provide a potential cost-effective approach for the control of TB are also available or under development, and a variety of results have been reported regarding the ability of these tests to detect infected animals, particularly in the early stages of infection. In the present study, SIT/CIT and IFN-γ tests and three different serological assays were evaluated during two consecutive herd testing events in a recently infected caprine herd (n = 447) with a high prevalence of infection in order to evaluate their performance and provide field data with which to improve the TB control programs in this species. The proportion of infected animals that tested positive among all the infected goats (T+/I+ value) in the last herd testing event ranged from 26.2% (IC95%; 19.3–34.5) to 85.7% (IC95%; 78.5–90.7) using cell-based diagnostic tests. The SIT/SCIT tests detected more infected goats than the IFN-γ test, regardless of the interpretation criteria. The T+/I+ value of serology was 83.2 (IC95%; 75.2–89), although it increased significantly (P < 0.05) when using samples collected 15 days after the intradermal test (100%, IC95%; 97–100). In general, a parallel interpretation of intradermal tests with serology maximized the detection of infected goats. These results demonstrate that serological tests are valuable diagnostic tools to maximize the detection of TB infected goats, even in recent outbreaks, accelerating the eradication process.

Prevalence of bovine and avian tuberculosis in camel herds and associated public health risk factors in Isiolo County, Kenya.

A cross-sectional study was conducted among 308 lactating camels selected from 15 herds from three different camel milk clusters in Isiolo County, Kenya, to determine prevalence of bovine and avian tuberculosis using Single Comparative Intradermal Tuberculin Skin test. Seventy-five (75) questionnaires were administered to pastoralists/herders, and focus group discussions were conducted among 3-5 pastoralists/herders selected from each camel herd to collect information on camel husbandry and health management practices and knowledge on tuberculosis in livestock and wildlife. An overall prevalence of bovine and avian reactors was 3.57 and 18.18%, respectively, with bovine and avian reactors for different clusters being 2.38, 3.82, and 4.48% and 25, 17.2, and 11.94%, respectively. There was significant difference (p < 0.05) in prevalence of bovine and avian reactors between different clusters. There was a negative correction (r = -0.1399) between herd size and bovine reactors, while there was a positive correlation (r = 0.0445) between herd size and avian reactors. The respondents indicated that camel herds are exposed to several risk factors like close contact with other herds or livestock or wildlife during grazing and at watering points. Pastoralists have poor knowledge on mode of infection and transmission of bovine or avian tuberculosis. The high prevalence of bovine and avian reactors and pastoralists' poor knowledge on mode of transmission signify potential risk to public health.

A cross-sectional study on prevalence of bovine tuberculosis in Indian and crossbred cattle in Gangetic delta region of West Bengal, India

Aim : The aim of this study was to investigate the incidence of bovine tuberculosis (BTB), an old chronic disease having zoonotic potential, covering four districts in Gangetic delta region of West Bengal, India, and to find the prevalence in organized as well as backyard herds and variation in relation to their age, sex, and breeds. Methods : The incidence of BTB in exotic and indigenous breeds of cattle (n=173) of various age groups was investigated employing tuberculin (single intradermal tuberculin and comparative cervical tuberculin) tests and gamma interferon assay. Further, milk samples (n=96) from milching animals and antemortem (n=519) samples (nasal swab, buccal swab, and aspirates from pre-scapular lymph nodes) were also screened employing bacteriological and molecular techniques. Results : In total, 36 (25.4%) animals from organized and one (3.2%) from backyard farming sector were found positive to BTB. Polymerase chain reaction (PCR) of milk samples based on 16S rRNA amplified the 1030 bp band in four samples indicating them belonging to genus Mycobacterium. Species-specific primers used to differentiate between Mycobacterium bovis and M. tuberculosis confirmed the presence of M. bovis. Prevalence of BTB in exotic crossbred animals (34.6%) was significantly higher (p<0.001) compared to indigenous cattle (10.5%). Further, gender-wise analysis of data with respect to BTB revealed higher positivity (p<0.05) among cows/heifers (25.8%) compared to bulls/bullocks (7.3%). Although BTBpositive cattle were detected in all the age groups, no statistical difference (p=0.779) was found among them. Conclusion : The findings indicate a higher prevalence of BTB in exotic crossbred animals in Gangetic delta and variation in breed susceptibility, thereby suggesting an urgent review of the present policy on adopting national crossbreeding program and implementation of “One Health” approach.

Antibody detection tests improve the sensitivity of tuberculosis diagnosis in cattle

We evaluated the sensitivity (Se) of the single cervical intradermal tuberculin (SIT) test, two interferon-gamma (IFN-γ) assays and three different antibody detection techniques for bovine tuberculosis (bTB) diagnosis in 131 mixed beef breed cattle. The results of the diagnostic techniques performed over the whole herd, and over the animals confirmed as infected based on the presence of lesions compatible with the disease and/or M. bovis isolation were compared to determine apparent prevalence (AP) and Se.The Se of the SIT test (severe interpretation) was 63.7% (95% CI, 54.54–72.00), while the Se of the IFN-γ assays ranged between 60.2% and 92%. The proportion of infected cattle detected by the different antibody detection techniques ranged from 65.5% to 87.6%. Three of the antibody detection techniques yielded a significant higher (p<0.05) Se than that achieved with the official diagnostic techniques. In addition, the interpretation in parallel of cellular and antibody detection techniques reached the highest Se: 98.2% (95% CI, 93.78–99.51) suggesting that the use of diagnostic techniques detecting both cellular and humoral responses could be considered as an alternative in the control of bTB outbreaks in high prevalence settings.

Factors Affecting Herd Status for Bovine Tuberculosis in Dairy Cattle in Northern Thailand.

The objective of this case-control study was to identify farm-level risk factors associated with bovine tuberculosis (bTB) in dairy cows in northern Thailand. Spatial analysis was performed to identify geographical clustering of case-farms located in Chiang Mai and Chiang Rai provinces in northern Thailand. To identify management factors affecting bTB status, a matched case-control study was conducted with 20 case-farms and 38 control-farms. Case-farms were dairy farms with at least single intradermal tuberculin test- (SIT-) reactor(s) in the farms during 2011 to 2015. Control-farms were dairy farms with no SIT-reactors in the same period and located within 5 km from case-farms. Questionnaires were administered for data collection with questions based on epidemiological plausibility and characteristics of the local livestock industry. Data were analyzed using multiple logistic regressions. A significant geographic cluster was identified only in Chiang Mai province (p < 0.05). The risk factor associated with presence of SIT-reactors in dairy herds located in this region was purchasing dairy cows from dealers (OR = 5.85, 95% CI = 1.66–20.58, and p = 0.006). From this study, it was concluded that geographic clustering was identified for dairy farms with SIT-reactors in these provinces, and the cattle movements through cattle dealers increased the risks for SIT-reactor farm status.

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.

Sensitivity of γ-interferon test used in series after tuberculin test to detect bovine tuberculosis

FRANCE has been officially bovine tuberculosis (bTB) free since 2000, but an increase in the number of outbreaks has been observed in some areas. bTB is detected through inspections at...

Risk factors for failure to detect bovine tuberculosis in cattle from infected herds across Northern Ireland (2004–2010)

Correctly identifying animals that are truly infected with a pathogen using ante-mortem tests is the cornerstone of any disease eradication programme. Failure to identify all infected animals will impede the progress towards controlling and eradicating disease and may also have unforeseen consequences when specific prevention measures are in place to avoid animal-to-animal transmission. In the case of bovine tuberculosis (bTB), the screening ante-mortem test, the Single Comparative Intradermal Tuberculin Test (SCITT), can exhibit moderate sensitivity which can result in a “hidden burden” of infection residing within the population. Using an animal-level dataset relating to the disclosure of infected cattle with Mycobacterium bovis, the causative agent of bTB within infected herds in Northern Ireland, we investigated what factors influenced the probability of an animal being a false-negative when truly infected (using post-mortem (PM) microbiological culture confirmation results to assess infection status).We found that different risk factors affected the probability of a test-negative outcome on infected animals depending on the ante-mortem test or their combination (SICTT and/or interferon gamma (IFN-ɣ) testing). Using multivariable models, SCITT disclosure performance varied significantly by age, location (region), and production type. The IFN-ɣ tests were significantly affected by region or season, but these effects depended on the cut-off used during interpretation of the test which affected the tests characteristics. Parallel use of SCITT and IFN-ɣ tests resulted in the least number of false-negatives, and their disclosure was affected by season and age-class.Understanding the factors that lead to the non-disclosure of infected animals is essential to optimise large-scale bTB disease eradication programmes.

Evidence of Mycobacterium tuberculosis complex bacteraemia in intradermal skin test positive cattle detected using phage-RPA

ABSTRACTBovine tuberculosis is a zoonotic infectious disease caused by Mycobacterium bovis that affects cattle and can cause tuberculosis in a range of wildlife animals. A bacteriophage-based method combined with PCR (phage-PCR) has been recently used to detect and identify viable pathogenic mycobacteria in the peripheral blood mononuclear cells (PBMCs) of animals suffering from paratuberculosis. To adapt this method for the detection of M. bovis in blood, a new isothermal DNA amplification protocol using Recombinase Polymerase Amplification (RPA) was developed and was found to be able to detect M. bovis BCG within 48 h, with a limit of detection of approximately 10 cells per ml of blood for artificially inoculated blood samples. When blood samples (2 ml) from a Single Comparative Cervical Intradermal Tuberculin (SCCIT)- negative beef herd were tested, Mycobacterium tuberculosis complex (MTC) cells were not detected from any (45) of the blood samples. However when blood samples from SCCIT-positive animals were tested, viable MTC bacteria were detected in 66 % (27/41) of samples. Of these 41 animals sampled, 32 % (13) had visible lesions. In the visible lesion (VL) group, 85 % (11/13) had detectable levels of MTC whereas only 57 % (16/28) of animals which had no visible lesions (NVL) were found to have detectable mycobacteraemia. These results indicated that this simple, rapid method can be applied for the study of M. bovis infections. The frequency with which viable mycobacteria were detected in the peripheral blood of SCCIT-positive animals changes the paradigm of this disease.

Single nucleotide polymorphisms in toll-like receptor genes and case-control association studies with bovine tuberculosis

Aim:Toll-like receptor 2 (TLR2) and TLR4 genes play critical roles in host recognition of Mycobacterium bovis infection and initiation of innate and adaptive immune response. The present study was aimed at exploring the association of seven single nucleotide polymorphisms (SNPs) in TLR2 and TLR4 genes with susceptibility/resistance against bovine tuberculosis (bTB) infection in cattle.Materials and Methods:A case-control resource population of 35 positive and 45 negative animals was developed after screening with single intradermal tuberculin test for bTB. Resource population was screened for SNPs in TLR2 and TLR4 genes using polymerase chain reaction-restriction fragment length polymorphism. The PROC LOGISTIC procedure of SAS 9.3 was used to find an association of allelic and genotypic frequencies with bTB.Results:In TLR2 gene, two of SNPs under study (rs55617172 and rs68268253) revealed polymorphism while in the case of TLR4 gene all four SNPs under investigation (rs8193041, rs207836014, rs8193060, and rs8193069) were found to be polymorphic in case-control population. SNP locus rs55617172 in TLR2 gene was found significantly (p<0.01) associated with susceptibility/resistance to TB in cattle.Conclusion:These findings indicate the presence of SNPs in TLR2 and TLR4 genes in our resource population. Upon validation in independent, large resource population and following biological characterization, SNP rs55617172 can be incorporated in marker panel for selection of animals with greater resistance to bTB.

First results on small ruminant brucellosis and tuberculosis and caprine arthritis-encephalitis in El Salvador.

This paper reports a first-time study performed in El Salvador on the presence or absence of antibodies to three important animal diseases in small ruminants. The work was conducted in the west and central departments of the country, selecting 42 and 43 cantons with an existing sheep and goat population, respectively. Serum samples were collected from 396 sheep and 335 goats and tested for seropositivity to Brucella (B.) spp. The specimens from goats were also tested for antibodies to caprine arthritis-encephalitis (CAE) virus. Four (1%) sheep and none of the goats were seropositive by Rose Bengal test. All animals were negative by indirect ELISA (iELISA) for B. abortus. All animals were negative by iELISA for CAE. A total of 383 sheep and 330 goats underwent the single intradermal cervical tuberculin (SICT) test for tuberculosis. Seventy (18%) sheep and 43 (13%) goats reacted to the SICT test. Those reactors were subjected to the single intradermal comparative cervical tuberculin (SICCT) test, and one (0.3%) goat was deemed to be a positive reactor. No mycobacteria were diagnosed in concluding analyses, and further studies are considered necessary to determine the prevalence of the investigated diseases. Additionally, it is recommended that small ruminants should be included in the national eradication program on bovine brucellosis and tuberculosis to prevent potential reservoirs.

Preliminary Study on the Prevalence of Bovine Tuberculosis and Risk Factors among Pastoralists in Gombe State, North Eastern Nigeria

A cross-sectional study was conducted in GombeState (North- eastern, Nigeria) from March, 2011 to April 2013 to estimate the prevalence of bovine tuberculosis (BTB) based on single caudal intradermal tuberculin test (SCITT), questionnaire and an abattoirs survey. The study was conducted among 250 households (100 household with a history or confirmed case of pulmonary tuberculosis and 150 households who had no history or confirmed case of pulmonary Tb), who raised 217 herds comprising of 2,245 herds of cattle. Questionnaire administration and Bioline® analysis of sputa collected from all pastoralists who were suspected to have TB and were smear positive were also conducted. Herd prevalence of SCITT was 13.87% and was higher than in herds of the negative households. At least one human Tb case was observed among 25% of the households interviewed, whereas 48% had reactor cattle. However, there was no statistically significant association (P>0.05) between the human Tb cases observed and the presence of reactor cattle. Similarly, fourty (40) isolates of Mycobacteria spp were obtained from the cultured sputa collected from the pastoralists, and were subjected to Ziehl-Nelson (ZN) and Bioline® analysis, where sixteen (16) of the (40%) were found to be M. tuberculosis complex (MTC) and the remaining 24 (60%) were members of Non- tuberculous Mycobacteria (NTM). All the isolates obtained (both sputum and tissues) which were identified as MBTC, were subjected to genotype MBTC ® Hain assay PCR analysis in order to differentiate them in to their various species of the MBTC isolates from the tissues, 8 (4.0%) were found to be M. bovis, 5(2.5%) wereM.tb and the remaining 5(2.5%) were unidentified using the standard banding patterns. The 40MBTC from sputum were analyzed as follows, 30 (75%) as M.tb, 6(15%) were M. bovis and 3(7.5%) were M. africanum. The remaining 1(0.4%) were unidentified using the standard banding patterns. All the isolates obtained (both sputum and tissues) which were identified as MBTC, were subjected to genotype MBTC ® Hain assay PCR analysis in order to differentiate them in to their various species of the MBTC isolates from the tissues, 8 (4.0%) were found to be M. bovis, 5(2.5%) wereM. tb and the remaining 5(2.5%) were unidentified using the standard banding patterns. The 40MBTC from sputum were analyzed as follows, 30 (75%) as M.tb, 6(15%) were M. bovis and 3(7.5%) were M. africanum. The remaining 1(0.4%) were unidentified using the standard banding patterns. However, a significant difference (p>0.05) was observed among the cattle age group, cattle over five (5) years were seen to have higher odds for tuberculin reactivity compared to those below the age of five (5). Out of the total cattle population (57,943) subjected to post mortem examination at the abattoir, 205 were found to be positive for gross Tb lesions, where a large proportion (50%) of the lesions were recorded in the respiratory pathway, digestive system (21%) and prescapular lymph nodes (18.6%). In spite of all these findings, it was observed that 70% (175 out of 250) of the respondents had knowledge of the existence of the disease but did not know the zoonotic implication. Also, all the potential risk factors of the disease transmission between cattle and human (milk consumption, livestock husbandry and presence of Tb positive cattle) were not statistically significantly (P< 0.05). In conclusion, it was observed that cattle belonging to the pastoralists who were positive for Mycobacterium species were more affected than those who were negative and lack of zoonotic awareness of the households. Therefore, further study to differentiate the MTC (Mycobacterium tuberculosis complex) using molecular analysis, collaboration between physicians and veterinarians and creation of awareness about the zoonotic nature of the disease were recommended.

Prevalence of Avian Tuberculosis in Domestic Chickens in Selected Sites of Ethiopia

This study was conducted on 282 domestic chickens of Bahir Dar, Yilimana densa woreda, and Bishoftu by using avian tuberculosis diagnosis procedures such as single intradermal avian tuberculin test, post mortem examination, and Ziehl-Neelsen (Z-N) staining from tissue samples of naturally infected Domestic chickens (Gallus domesticus). The overall of this disease current prevalence was determined based on tuberculin skin test results supported by Z-N stain and post mortem lesions and it was 4.26% (12/282) (95% CI: 1.9-6.6), with higher prevalence in semi-intensively reared exotic chickens (5.85%) than backyard reared indigenous local chicken. This indicates the occurrence of this disease has a statistical significance association both with the breed and production system, both having a p-value of 0.03. Twelve strong positive reactor chickens have shown a swelling of greater than 5 mm in diameter 48 h. of post injection with different variety results, some with edematous swelling, and others with firm erythematic nodular swelling. Typical tuberculous lesions were seen mostly on the liver and spleen. From 12 tuberculi reactor slaughtered chickens, a total of seven (58.3%) chickens had gross lesions on different visceral organs, of which three (42.9%) examined chickens have manifested gross lesions on more than one organ. On acid fast staining five (41.67%) with grossly discernible lesions revealed acid-fast rods. For culturing, Lowenstein-Jensen (L-J) media was used as it yields more positive cultures, greater numbers of colonies on positive tubes, and shorter incubation times. None of the samples shown colonial growth till 8 weeks of incubation period and this may be due to the slow growth nature of mycobacterial species (especially when the infection was due to Mycobacterium avium subspecies paratuberculosis which needs a considerable long time for growth) and/or the current incubation temperature (37°C) may not be optimal as it does not fit the natural hosts internal body temperature and still the culture result is under process to see any growing colony. Therefore, this finding signaling an urgent need for intervention program to control the disease in domestic chickens and prevent zoonotic transmission.

Association of polymorphisms in SLC11A1 gene with bovine tuberculosis trait among Indian cattle

ABSTRACTIn the present study, polymorphisms at two single nucleotide polymorphisms (SNPs) and one microsatellite locus of SLC11A1 gene were investigated for finding their association with susceptibility to bovine tuberculosis trait (tuberculin reaction) in Indian cattle. A total of 245 animals were tested with single intradermal tuberculin test for screening positive animals for tuberculin reaction. At rs109915208 locus very low polymorphism information content of 0.0454 was observed, whereas it was moderate (0.352) at rs109453173 locus of SLC11A1. At rs109915208 locus the genotypic as well as allelic frequencies were differing significantly (p-value < .05) in case–control animals where the odds ratio (OR) of ‘CC’ verses ‘CT’ genotype and the OR of ‘C’ verses ‘T’ allele were approaching towards infinity, suggesting that animals having ‘CT’ genotype and ‘T’ allele were less susceptible for tuberculin reaction as compared to their contemporary genotype/allele. The significantly associated SNP was non-synonymous causing an amino acid change.

Pathology and diagnosis of Mycobacterium bovis in naturally infected dromedary camels (Camelus dromedarius) in India.

The present study investigated the pathological features of tuberculosis (TB) caused by Mycobacterium bovis and its diagnosis in naturally infected dromedary camels from an organized farm in India. During the period of the 5-year study, a total of 18 (19.56%) camels out of 92 examined showed gross lesions compatible with TB at post-mortem. The clinical signs and pathological lesions in these camels were studied, and the efficacy of different diagnostic tests was also assessed. On the basis of occurrence and distribution of gross TB lesions, the infected camels revealed two different lesional patterns as pulmonary (n = 15) and disseminated (n = 3) form. The histopathology of affected organs revealed typical granulomatous lesions wherein the giant cells and acid-fast bacilli were occasionally observed in pulmonary form whereas they frequently observed in disseminated form. The single intradermal tuberculin test (SIDT) detected TB in 10 (55.55%) whereas the Ziehl-Neelsen (ZN) stain and IS6110 PCR from tissue lesions detected 13 (72.22%) and 18 (100%) of the infected camels, respectively. The study suggests that pulmonary form of the TB is more common in camels indicating respiratory route as the major source of exposure in camel herds. Moreover, very low sensitivity of SIDT was observed which highlights the difficulty for confirmation of TB in live camels.