Single Intradermal Comparative Tuberculin Test Research Articles

Detection of specific antibodies in cows after injection of PPD

The diagnosis of bovine tuberculosis aims to identify the immune response against mycobacterial antigens. Although Single Intradermal Comparative Cervical Tuberculin test (SICCT) is broadly used for first identification of the disease, the performance of ELISAs has been investigated for diagnosis improvement. The present study expected to find out the influence of intradermal skin tests on the results of ELISAs using the recombinant proteins MPB70 and MPB83 as antigens on cows from a naturally infected herd. Results were analyzed by the F-test, Mann-Whitney and Friedman tests Although comparable to both proteins, results showed that positive animals presented a tendency of augment reactivity to MPB70, representing a tendency for a booster effect, but not to MPB83.

Bovine Tuberculosis and Brucellosis in Cattle and African Buffalo in the Limpopo National Park, Mozambique

Bovine tuberculosis (BTB) and brucellosis are prevalent in buffaloes of the Kruger National Park (KNP, South Africa). Both diseases were considered to have no or a very low prevalence in wildlife and livestock in and around the Limpopo National Park (LNP, Mozambique). The same applies for tuberculosis in Gonarezhou National Park (GNP, Zimbabwe), but just recently, BTB was detected in buffaloes in the GNP and fears arose that the disease might also spread to the LNP as a result of the partial removal of the fences between the three parks to form the Great Limpopo Transfrontier Park. To assess the status of both diseases in and around LNP, 62 buffaloes were tested for bovine tuberculosis (BTB) and bovine brucellosis. The percentage of positive BTB reactors in buffalo was 8.06% using BovidTB Stat-Pak® and 0% with BOVIGAM® IFN-γ test and IDEXX ELISA. The brucellosis seroprevalence in buffalo was found to be 17.72% and 27.42% using Rose Bengal Test (RBT) and ELISA, respectively. In addition, 2445 cattle in and around the LNP were examined for BTB using the single intradermal cervical comparative tuberculin test (SICCT), and an apparent prevalence of 0.98% was found with no significant difference inside (0.5%) and outside (1.3%) the park. This is the first published report on the presence of positive reactors to BTB and bovine brucellosis in buffalo and cattle in and outside the LNP. Monitoring the wildlife-livestock-human interface of zoonotic high-impact diseases such as BTB and brucellosis is of outmost importance for the successful implementation and management of any transfrontier park that aims to improve the livelihoods of the local communities.

Prevalence of tuberculosis among southern Zambian cattle and isolation of Mycobacterium bovis in raw milk obtained from tuberculin positive cows

Aim: To determine the prevalence of tuberculosis among traditional milking cows in southern Zambia and isolation of Mycobacterium spp from the tuberculin positive cow's milk. Materials and Methods: A total of 1,025 cows originating from traditional cattle sector, in Mapepe, Magoye, Monze, Batoka, GART- Batoka, Kalomo areas of Zambia, supplying major quantity of milk to milk processors, were tested for bovine tuberculosis using single comparative intra-dermal tuberculin test during 2011 and 2012. Milk samples obtained from 16 bovine tuberculin reactor cows were cultured for isolation of Mycobacterium spp and those showing growth of Mycobacterium spp. were identified through biochemical tests of the culture. Further confirmation and species differentiation of the Mycobacterium spp. isolates was done using the loop-mediated isothermal amplification system and multiplexpolymerase chain reaction Results: 27 (2.6%) of the cows tested were found tuberculin reactors, 9 cows (0.87 %) gave inconclusive reaction and 989 (96.48%) were non-reactors. Three milk samples (18.7%) out of the 16 tuberculin reactor cow's milk when cultured and upon molecular analysis, were found positive for presence of M. bovis indicating these positive cows were shedding M. bovis in their milk. Conclusion: The isolation of M. bovis in freshly drawn milk from the tuberculin positive reactor cows is being reported for the first time in Zambia. Bovine tuberculosis is an animal and human health risk in the traditional dairy herds supplying milk to the Zambian population especially in the informal market and needs attention of the public health and veterinary authorities.

Preliminary study on prevalence of bovine tuberculosis in cattle owned by tuberculosis positive and negative farmers and assessment of zoonotic awareness in Ambo and Toke Kutaye districts, Ethiopia

A cross sectional study was conducted from April to September, 2012 on cattle owned by tuberculosis positive and negative farmers and households to assess prevalence of bovine tuberculosis and zoonotic awareness of the households in Ambo and Guder districts, Ethiopia. A total of 398 cattle were tested using single comparative intradermal tuberculin test. The result was interpreted at >4 and >2 mm. An overall 1 and 4.02% prevalence of bovine tuberculosis at individual cattle and 7.02 and 24.56% at herd level were recorded at cut off >4 and >2 mm, respectively. Bovine tuberculosis was more prevalent in cattle owned by tuberculosis positive farmers (1.36 and 5% at individual cattle, 12 and 36% herd level) than in cattle owned by tuberculosis negative farmers (0.56 and 2.81% at individual cattle, 3.13 and 15.63% at herd level) at >4 and >2 mm cut off, respectively. Lack of awareness of the community about the zoonotic importance of the disease was observed. In conclusion, the present study indicated more prevalence of the disease in cattle owned by tuberculosis positive farmers than tuberculosis negative farmers and lack of zoonotic awareness of the households. Therefore, further study, collaboration between physician and veterinarians, and creation of awareness about zoonotic diseases were recommended. Key words: Bovine tuberculosis, cattle, prevalence, tuberculosis positive and negative farmers.

Tuberculosis transmission by Mycobacterium bovis in a mixed cattle and goat herd

A tuberculosis (TB) outbreak caused by Mycobacterium bovis occurred in a mixed herd of three cattle and eighteen goats in Northern Italy in 2005. All the cattle were removed, as opposed to the co-existing goats, who remained in the farm and were not subsequently tested by the official intradermal tuberculin test. At the beginning of May 2006, a 7-day old calf was introduced into the herd from an officially TB-free (OTF) farm. On October 2006, tuberculous lesions were detected at the slaughterhouse in the same animal. The following epidemiological investigation on the herd highlighted a clinical suspicion of TB in one goat out of 35, and visible lesions were found at necropsy in the respiratory and intestinal tracts. Bacteriological culture and molecular tests confirmed the presence of M. bovis in both animals. Spoligotyping and Mycobacterial Interspersed Repetitive Units – Variable Number of Tandem Repeats (MIRU-VNTR) showed the same genomic profile of the previous breakdown occurred in 2005. Since this profile has never been described in Italy, these findings suggest the probable transmission of TB within the farm among cattle and goats.The remaining 34 goats were also tested by single intradermal cervical comparative tuberculin (SICCT) test, Interferon (IFN)-γ assay and ELISA for antibody to M. bovis. The SICCT test and the IFN-γ showed a good concordance with 20 and 19 positive reactors, respectively. By ELISA we found 12Ab-positive animals, seven of which had not been detected by the tests for cell-mediated immunity. Finally, 15 goats were found positive for gross lesions at necropsy.The in vivo tests revealed a total of 27 positive animals out of 35, which highlights the usefulness of the serology in parallel with SICCT and IFN-γ when an advanced stage of infection is suspected. Moreover, our results confirm the necessity for adopting the official tuberculin test on goats co-existing with cattle.

Tuberculin screening of some selected Fulani lactating cows in North-Central Nigeria

The prevalence of mycobacterial infection among lactating Fulani cows was investigated in the Federal Capital Territory, Abuja and Kaduna State of Nigeria. Tuberculin testing using single comparative intradermal tuberculin test showed a 14.6 % positive, 4 % doubtful, and 81.4 % negative reactors. Mycobacterial infection was found to be present in the nomadic (constantly moving) and seminomadic (limited movement) management systems studied but management showed no significant effect on the prevalence of the disease. However, the prevalence was significantly higher in older age groups than the younger ones (P < 0.05).

Enhancing the sensitivity of tests for bovine TB

THE national programme to control bovine tuberculosis (TB) is over 80 years old. After some great successes and a reduction in incidence of herd breakdowns to less than one per...

Prevalence and significant geospatial clusters of bovine tuberculosis infection at livestock–wildlife interface ecosystem in Eastern Tanzania

Bovine tuberculosis (BTB) is an important neglected zoonosis that affects livestock, wildlife and human. A study to determine prevalence and geospatial clusters for BTB was conducted from June 2010 to March 2012 at livestock-wildlife interface areas (LWIA). A total of 1,288 cattle located in vicinity of Mikumi-Selous ecosystem Tanzania were tested. Single Intradermal Comparative Tuberculin Test and spatial scan statistic analysis were applied to establish the status of the disease and identify significant spatial BTB clusters. Overall individual prevalence was 3.7 % (n=1,288) (95 % CI=2.8-4.9) and 7.8 % (95 % CI=6.4-9.4) with cut-off of >4 and >2 mm, respectively. Villages with at least one reactor were 55.8 % (n=43). Reactivity was significantly higher in Mvomero and Kilosa districts compared with Kilombero and Ulanga districts (χ (2) =15.9; P<0.001). Significant spatial BTB clusters were revealed at 11 villages. BTB clustering was significant in Kilosa and Mvomero districts compared with Kilombero and Ulanga districts. There was overlap and aggregation of BTB clusters covering south and south-east of Kilosa district bordering Mikumi National Park (MNP) and Mvomero. Generally, clustering occurred around major rivers. The current study provides useful information on the dynamics and epidemiological status of BTB around the wildlife-livestock-human interface, it reveals that the wildlife are at risk of BTB from infected livestock. The study revealed hotspots for BTB that can be applied to guide implementation of participatory intervention at LWIA and control strategies in marginalised pastoralist communities. This study calls for similar studies in other Tanzania's LWIA for efficient intervention of BTB countrywide.

Mycobacterium bovis detection from milk of negative skin test cows

Mycobacterium bovis is the bovine tuberculosis (bTB) agent, which is still an important infection in bovine herds. Apart from this, bTB is also a zoonotic disease, and human beings can...

Bovine Tuberculosis and Brucellosis in Traditionally Managed Livestock in Selected Districts of Southern Province of Zambia

A study was performed in 2008 to estimate the prevalence of tuberculosis and brucellosis in traditionally reared cattle of Southern Province in Zambia in four districts. The single comparative intradermal tuberculin test (SCITT) was used to identify TB reactors, and the Rose Bengal test (RBT), followed by confirmation with competitive enzyme-linked immunosorbent assay (c-ELISA), was used to test for brucellosis. A total of 459 animals were tested for tuberculosis and 395 for brucellosis. The overall prevalence of BTB based on the 4 mm and 3 mm cutoff criteria was 4.8% (95% CI: 2.6–7.0%) and 6.3% (95% CI: 3.8–8.8%), respectively. Change in skin thickness on SCITT was influenced by initial skin-fold thickness at the inoculation site, where animals with thinner skin had a tendency to give a larger tuberculin response. Brucellosis seroprevalence was estimated at 20.7% (95% CI: 17.0–24.4%). Comparison between results from RBT and c-ELISA showed good agreement (84.1%) and revealed subjectivity in RBT test results. Differences in brucellosis and tuberculosis prevalence across districts were attributed to type of husbandry practices and ecological factors. High prevalence of tuberculosis and brucellosis suggests that control programmes are necessary for improved cattle productivity and reduced public health risk.

Prevalence and risk factors for infection of bovine tuberculosis in indigenous cattle in the Serengeti ecosystem, Tanzania

BackgroundBovine tuberculosis (bTB) is a chronic debilitating disease and is a cause of morbidity and mortality in livestock, wildlife and humans. This study estimated the prevalence and risk factors associated with bovine tuberculosis transmission in indigenous cattle at the human-animal interface in the Serengeti ecosystem of Tanzania.ResultsA total of 1,103 indigenous cattle from 32 herds were investigated for the presence of bTB using the Single Intradermal Comparative Tuberculin Test. Epidemiological data on herd structure, management and grazing system were also collected.The apparent individual animal prevalence of tuberculin reactors was 2.4% (95% confidence interval (CI), 1.7 – 3.5%), whereas the true prevalence was 0.6% CI, 0.6 – 0.7% as indicated by a reaction to avian tuberculin purified protein derivatives (PPD) which is more than 4 mm greater than the reaction to avian tuberculin PPD. The results showed that 10.6% (117/1,103) showed non-specific reactions (atypical mycobacterium). The herd prevalence of 50% (16/32) was found. Tuberculin skin test results were found to be significantly associated with age, location, size of the household and animal tested. Of 108 respondents, 70 (64.8%) individuals had not heard about bovine tuberculosis at all. Thirty five percent (38/108) of respondents at least were aware of bTB. About 60% (23/38) of respondents who were aware of bTB had some knowledge on how bTB is spread. Eighty one percent (87/108) of respondents were not aware of the presence of bTB in wildlife. There is regular contact between cattle and wild animals due to sharing of grazing land and water sources, with 99% (107/108) of households grazing cattle in communal pastures.ConclusionThe study has demonstrated a high reported interaction of livestock with wildlife and poor knowledge of most cattle owners concerning bTB and its transmission pathways among people, livestock and wildlife. Although the overall proportion of animals with bTB is relatively low, herd prevalence is 50% and prevalence within herds varied considerably. Thus there is a possibility of cross transmission of bTB at wildlife-livestock interface areas that necessitates use of genetic strain typing methods to characterize them accurately.

Quality control in the national bovine tuberculosis eradication programme in Ireland

The Irish bovine tuberculosis (BTB) eradication programme operates under national legislation and fulfils the requirements of the European Union Trade Directive 64/432. The programme includes annual single intradermal comparative tuberculin test (SICTT) screening of all herds, prompt removal of test reactors and further consequential retesting of herds. Continuous evaluation of all relevant activities is essential to deliver an effective national programme and to reassure all stakeholders thatthe highest possible standards are attained. Quality control (QC) is a recognised process in the delivery of quality products or services. This paper presents a review of QC in the BTB eradication programme in Ireland, with particular emphasis on field surveillance and the assessment of private veterinary practitioner performance. A broad range of programme elements subjected to QC are described, including personnel, training, equipment, tuberculins and laboratories.

Tuberculin manufacturing source and breakdown incidence rate of bovine tuberculosis in British cattle, 2005–2009

The single intradermal comparative cervical tuberculin (SICCT) test is the primary test used for surveillance for bovine tuberculosis (bTB) in cattle in Great Britain (GB). The tuberculin used can, with...

The impact of animal introductions during herd restrictions on future herd-level bovine tuberculosis risk

In Ireland new cases of bovine tuberculosis (bTB) are detected using both field (with the single intradermal comparative tuberculin test (SICTT)) and abattoir surveillance. Once a new case has been detected, herd restrictions, including restrictions on animal movements into and out of the herd, are implemented until the herd has passed two consecutive clear tests. While a herd is restricted, there may be several reasons why it may be desirable to introduce new stock, such as enabling routine management practices to continue ‘as near to normal’. In Ireland, introduction of animals during a bTB episode is permitted under specific conditions, with permission from the local veterinary office.The objectives of this study were (1) to provide an overview of movement events associated with each bTB episode, (2) to determine whether introduction of animals during a bTB episode is associated with increased future bTB risk and (3) to identify the practices relating to the introduction of animals that are the most risky.All herds that were not restricted at the start of 2006, but experienced a bTB episode during 2006 with 2 or more SICTT standard reactors (the eligible bTB episode) were included in the study. We calculated the number of extended eligible bTB episodes and subsequent bTB episodes that could be directly attributed to introduced animals. The main outcome of interest was the time from de-restriction of the eligible bTB episode to the start of a subsequent bTB episode or the date of the last test prior to the end of the study (31 December 2010). Cox proportional-hazard models were developed, each using a different introduction variable: introduced animals during an episode (yes/no), introduced animals prior to the first retest/first clear test, time from start of episode until first animals introduced and number of animals introduced during the episode.Only a small proportion of subsequent bTB episodes (1.8%) or extended eligible bTB episodes (2.7%) could be directly attributed to introduced animals. The results highlight an increased risk of a subsequent bTB episode among only a subset of herds that introduced animals during the eligible bTB episode. Specifically, herds that introduced animals early during the eligible bTB episode were at significantly greater future bTB risk than herds where animals were only introduced later. To illustrate, herds that introduced animals after the first retest did not have a significantly different risk compared to herds that did not introduce animals at all. In contrast, herds that did introduce animals prior to the first retest had 1.5 times higher risk of a subsequent bTB episode. Future practices concerning the introduction of animals during an episode now need to be reviewed.

Estimation of the Relative Sensitivity of the Comparative Tuberculin Skin Test in Tuberculous Cattle Herds Subjected to Depopulation

Bovine tuberculosis (bTB) is one of the most serious economic animal health problems affecting the cattle industry in Great Britain (GB), with incidence in cattle herds increasing since the mid-1980s. The single intradermal comparative cervical tuberculin (SICCT) test is the primary screening test in the bTB surveillance and control programme in GB and Ireland. The sensitivity (ability to detect infected cattle) of this test is central to the efficacy of the current testing regime, but most previous studies that have estimated test sensitivity (relative to the number of slaughtered cattle with visible lesions [VL] and/or positive culture results) lacked post-mortem data for SICCT test-negative cattle. The slaughter of entire herds (“whole herd slaughters” or “depopulations”) that are infected by bTB are occasionally conducted in GB as a last-resort control measure to resolve intractable bTB herd breakdowns. These provide additional post-mortem data for SICCT test-negative cattle, allowing a rare opportunity to calculate the animal-level sensitivity of the test relative to the total number of SICCT test-positive and negative VL animals identified post-mortem (rSe). In this study, data were analysed from 16 whole herd slaughters (748 SICCT test-positive and 1031 SICCT test-negative cattle) conducted in GB between 1988 and 2010, using a Bayesian hierarchical model. The overall rSe estimate of the SICCT test at the severe interpretation was 85% (95% credible interval [CI]: 78–91%), and at standard interpretation was 81% (95% CI: 70–89%). These estimates are more robust than those previously reported in GB due to inclusion of post-mortem data from SICCT test-negative cattle.

Development of a diagnostic gene expression assay for tuberculosis and its use under field conditions in African buffaloes (Syncerus caffer)

The development of diagnostic tests for tuberculosis (TB) in exotic species is constrained by host biology and the limited availability of suitable assay reagents. As such, we evaluated a gene expression assay (GEA) which is easily modified for novel species and allows for initial sample processing under field conditions. African buffaloes (Syncerus caffer) were categorized using the single comparative intradermal tuberculin test, and blood from test-positive and test-negative animals was incubated for 20h in “Nil” tubes (containing saline) and “TB Antigen” tubes (containing Mycobacterium tuberculosis complex (MTC)-specific antigens) of a commercial human TB test, the QuantiFERON®-TB Gold (In-Tube) (QFT) assay. Blood samples were then stabilized in RNAlater® and transported to the laboratory for RNA extraction. A Custom TaqMan GEA was used to calculate the relative abundance of interferon-gamma (IFN-γ) mRNA in the TB Antigen tube compared to that in the Nil tube as a marker of immune activation in response to MTC antigen recognition. The GEA results from the two buffalo groups were compared and a cutoff value of 2.85 was calculated to differentiate between animals from these groups with a sensitivity of 80% (95% C.I.: 56–94%) and a specificity of 95% (95% C.I.: 75–100%). Further optimization of this assay could provide a highly useful tool for the diagnosis of MTC infection in exotic species.

Evaluation of single reactor bovine tuberculosis breakdowns based on analysis of reactors slaughtered at an Irish export meat plant

The ‘Singleton Protocol’ was adopted by the Irish Department of Agriculture Fisheries and Food (DAFF) in 1996 to address the incomplete specificity of the single intra-dermal comparative tuberculin test (SICTT)...

The Accuracy of the Single Intradermal Comparative Skin Test for the Diagnosis of Bovine Tuberculosis-Estimated from a Systematic Literature Search

Background: Bovine Tuberculosis (bTN) elimination programs are based on test-and-slaughter strategies. No diagnostic test used in the control of Bovine Tuberculosis (bTB), a zoonotic disease, is a perfect gold standard having a diagnostic sensitivity and specificity of 100%. Methods: To find relevant data to assess diagnostic accuracy of one variant of the tuberculin test, the Single Intradermal Comparative Cervical Tuberculin Test (SICCT) used in the diagnosis of bTB a systematic literature search was performed. To estimate diagnostic test accuracies of the SICCT, a Bayesian latent class analysis has been undertaken. Results: Only one eligible study was found. Assuming bacterial isolation has a specificity of 100%, specificity of gross lesion detection and histopathology were estimated as 90% and 97% respectively. Estimates of the sensitivity of the Single Intradermal Comparative Cervical Tuberculin Test (SICCT), gross lesion detection, histopathology and bacteriological isolation were 80%, 89%, 93% and 98% respectively. The design of this study precluded estimating the SICCT specificity, although official UK surveillance data indicates specificity greater than 99.67%. Conclusion: Studies to estimate the diagnostic performance of key tests for bTB are lacking, yet essential for an informed debate in regard to bTB public health policy.

Fasciola hepatica is associated with the failure to detect bovine tuberculosis in dairy cattle

Bovine tuberculosis (BTB) is a significant and intractable disease of cattle caused by Mycobacterium bovis. In the UK, despite an aggressive eradication programme, the prevalence of BTB is increasing with an unexplained, exponential rise in cases year on year. Here we show in a study involving 3026 dairy herds in England and Wales that there is a significant negative association between exposure to the common, ubiquitous helminth parasite, Fasciola hepatica and diagnosis of BTB. The magnitude of the single intradermal comparative cervical tuberculin test used to diagnose BTB is reduced in cattle experimentally co-infected with M. bovis and F. hepatica. We estimate an under-ascertainment rate of about one-third (95% Confidence Intervals 27-38%) among our study farms, in the hypothetical situation of no exposure to F. hepatica. This finding may in part explain the continuing spread of BTB and the failure of the current eradication programme in the UK.

Comparison of decontamination methods for primary isolation of Mycobacterium bovis in paucibacillary bovine tissues

To compare three decontamination methods applied to paucibacillary samples for primary isolation of Mycobacterium bovis from suspect lesions. Tuberculosis caused by Myco. bovis is an important infectious disease of cattle in Brazil and also has zoonotic potential. Although a national campaign based on testing and slaughtering cattle has achieved good results, there is a strong need to develop better diagnostic methods to identify cattle with recent infections harbouring few bacilli. A dairy herd (274 adult crossbred cows) located in the state of Rio de Janeiro was tested for tuberculosis with both single intradermal tuberculin test and comparative intradermal tuberculin test. Reactive cows (n=27, 9.8%) were slaughtered and suspect lesions were collected (one sample per cow). Samples considered paucibacillary (based on microscopy) were decontaminated with 0.75% hexadecylpyridinium chloride (HPC), 4% sodium hydroxide (Petroff) or 6% sulphuric acid. Using these methods, 10, five and six, respectively, of the 27 samples yielded positive cultures. Overall, Myco.bovis was isolated from 14 of 24 cows. Although the HPC method resulted in isolation of more Myco.bovis strains than either Petroff or sulphuric acid methods (P=0.015), it did not result in the recovery of Myco.bovis from all samples. However, using both HPC and 6% sulphuric acid methods for decontamination was possible to identify 13 of 14 (92·9%) of infected cows. At least two methods should be used concurrently for primary isolation of Myco. bovis from bovine tissues, particularly for paucibacillary samples. Detection of low numbers of Myco.bovis in tissue is an important goal in optimizing the detection of bovine tuberculosis and should assist in identification of infected cattle, in particular, those with few Myco.bovis bacilli. This was apparently the first study comparing three decontamination methods for the detection of Myco.bovis in paucibacillary samples from naturally infected cattle.