Bovine TB: Research project summary
Project SE3118: Review and economic analysis of the use of rapid methods for M. tuberculosis complex detection and identification in the bovine TB control programme.
Project duration: 6 months
Recent developments in rapid detection methods for MTB (Mycobacterium
Tuberculosis) complex, such as PCR (Polymerase Chain Reaction), have
the potential to improve the cost-effectiveness of detection and identification
of M. bovis in tissue samples. This project produced a critical
review of all current rapid detection methods available for the detection
and identification of M. bovis. Options for incorporation of
such methods into routine bovine TB testing, and any costs and benefits
were also evaluated.
A number of potential rapid detection systems for MTB complex were reviewed.
While some of these show great promise, for example, nanotechnology, they
all require further development. There is no obvious method to replace
PCR in the immediate future.
The IS1081 PCR (Defra project SE3008) was considered to be the most suitable PCR assay, and was therefore used in assessing the feasibility of using PCR in detection of M. bovis in cattle tissue samples. PCR will provide most value when applied to samples from herds that are not known to be infected with M. bovis, since a rapid result will reduce the chance of further infection within and between herds. The two cattle populations assessed in this project were therefore herds from which: visible lesions were detected in an animal at the slaughterhouse (SLH); or one non-visible lesion, skin test-positive animal was detected (NVL reactor).
PCR was considered to be economically worthwhile in SLH cases, particularly if it replaced histopathological examination. It may also be economically worthwhile to replace culture with PCR in NVL reactor cases, and forego the ability to spoligotype these strains, since the proportion of M. bovis positive animals in this group is small.
Several assumptions were made in this analysis, and the financial saving from using PCR may not be as high as predicted since administrative costs are currently imbedded in the cost of culture. In addition, future developments in PCR sensitivity, and the ability to type M. bovis strains from DNA extracted directly from tissue samples, could increase the number of situations to which PCR could provide an economic benefit. Further research is therefore recommended.
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Page last modified:
July 7, 2008