Test Characteristics of Assays to Detect Mycobacterium bovis Infection in High-Prevalence African Buffalo (Syncerus caffer) Herds

Bernitz, Netanya; Kerr, Tanya J.; Waal, Candice R. de; Cooper, David; Warren, Robin M.; Helden, Paul D. van; Parsons, Sven D.C.; Miller, Michele A.

doi:10.7589/2019-06-173

Cited by 9 publications

(8 citation statements)

References 12 publications

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“…This result was expected, since IP-10 is known to be a more sensitive cytokine biomarker compared to IFN-γ [9]. The specificity for IPRA in the current study was higher than that reported by Bernitz et al [14] at 67%. However, Bernitz et al [14] determined specificity in M. bovis culture-negative buffaloes from a bTB endemic herd.…”

Section: Discussionsupporting

confidence: 43%

“…The fourth tube (QFT TB1) only contains CD4 stimulating antigens. Following 100% agreement in test outcomes from TB1 and TB2 tubes in a previous study [14], the TB1 tube was not included for these buffaloes. After inverting all tubes 10 times, tubes were incubated at 37°C for 24 h, prior to harvesting plasma fractions by centrifugation at 3000 rpm for 15 min.…”

Section: Animals and Sample Collectionmentioning

confidence: 99%

“…Although current guidelines for testing buffaloes in South Africa rely on the SCITT, the use of parallel testing has been shown to improve detection of infected animals [4,9,14]. With increased sensitivity, there is a trade-off in specificity, resulting in culling of some false-positive buffaloes, which is of lesser concern when attempting to eradicate bTB in a herd [9].…”

Section: Introductionmentioning

confidence: 99%

“…However, a fitfor-purpose high specificity algorithm has not been evaluated in African buffaloes. Previous studies, to determine bTB test specificity values, used buffaloes that were M. bovis culture-negative, but from exposed herds (bTB endemic herds), which may result in an inaccurate estimate of specificity [14]. Therefore, this study aimed to 1) determine individual specificities of the QFT Mabtech IGRA, QFT IPRA, and SCITT in known M. bovis unexposed African buffaloes, 2) evaluate test algorithms to optimise specificity in these M. bovis unexposed buffalo herds, 3) determine if there is an association between falsepositive bTB test results in M. bovis unexposed herds and presence of NTMs, and 4) apply the high specificity testing algorithm to an unrelated historically bTB-free herd as a proofof-principle.…”

Section: Introductionmentioning

confidence: 99%

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High Specificity Test Algorithm for Bovine Tuberculosis Diagnosis in African Buffalo (<em>Syncerus caffe</em>r) Herds

Clarke¹,

Bernitz²,

Goosen³

et al. 2022

Preprint

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Ante-mortem bovine tuberculosis (bTB) tests for buffaloes include the single comparative intradermal tuberculin test (SCITT), interferon-gamma (IFN-γ) release assay (IGRA) and IFN-γ-inducible protein 10 release assay (IPRA). Although parallel test interpretation increases detection of Mycobacterium bovis-infected buffaloes, these algorithms may not be suitable for screening buffaloes in historically bTB-free herds. In this study, the specificities of three assays were determined using M. bovis unexposed herds, and a high specificity diagnostic algorithm developed. Serial test interpretation using the IGRA and IPRA showed significantly greater specificity (98.3%) than individual tests or parallel testing (73%). When the SCITT was added, the algorithm had a 100% specificity. Since the cytokine assays had imperfect specificity, potential cross-reactivity with nontuberculous mycobacteria (NTM) was investigated. No association was found between NTM presence (in oronasal swab cultures) and positive cytokine assay results. As a proof-of-principle, serial testing was applied to high-value buffaloes (n=153) in a historically bTB-free herd. Buffaloes positive on a single test (n=28) were regarded as test negative. Four buffaloes were positive on IGRA and IPRA, and M. bovis infection was confirmed following culling. These results demonstrate the value of using IGRA and IPRA in series to screen buffalo herds with no previous history of M. bovis infection.

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Section: Discussionsupporting

confidence: 43%

Section: Animals and Sample Collectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High Specificity Test Algorithm for Bovine Tuberculosis Diagnosis in African Buffalo (<em>Syncerus caffe</em>r) Herds

Clarke¹,

Bernitz²,

Goosen³

et al. 2022

Preprint

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“…Since no single cytokine release assay has perfect sensitivity and specificity ( 80 ), biomarker panels are being investigated to improve diagnostic performance. The parallel measurement of IFN-γ and IP-10 has been shown to maximize the detection of M. bovis -infected African buffaloes while maintaining specificity ( 13 ).…”

Section: Indirect Detectionmentioning

confidence: 99%

Review of Diagnostic Tests for Detection of Mycobacterium bovis Infection in South African Wildlife

et al. 2021

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Wildlife tuberculosis is a major economic and conservation concern globally. Bovine tuberculosis (bTB), caused by Mycobacterium bovis (M. bovis), is the most common form of wildlife tuberculosis. In South Africa, to date, M. bovis infection has been detected in 24 mammalian wildlife species. The identification of M. bovis infection in wildlife species is essential to limit the spread and to control the disease in these populations, sympatric wildlife species and neighboring livestock. The detection of M. bovis-infected individuals is challenging as only severely diseased animals show clinical disease manifestations and diagnostic tools to identify infection are limited. The emergence of novel reagents and technologies to identify M. bovis infection in wildlife species are instrumental in improving the diagnosis and control of bTB. This review provides an update on the diagnostic tools to detect M. bovis infection in South African wildlife but may be a useful guide for other wildlife species.

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Development of a cytokine gene expression assay for the relative quantification of the African elephant (Loxodonta africana) cell-mediated immune responses

et al. 2021

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Test Characteristics of Assays to Detect Mycobacterium bovis Infection in High-Prevalence African Buffalo (Syncerus caffer) Herds

Cited by 9 publications

References 12 publications

High Specificity Test Algorithm for Bovine Tuberculosis Diagnosis in African Buffalo (<em>Syncerus caffe</em>r) Herds

High Specificity Test Algorithm for Bovine Tuberculosis Diagnosis in African Buffalo (<em>Syncerus caffe</em>r) Herds

Review of Diagnostic Tests for Detection of Mycobacterium bovis Infection in South African Wildlife

Development of a cytokine gene expression assay for the relative quantification of the African elephant (Loxodonta africana) cell-mediated immune responses

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