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Collection of resource material for Johne's disease test validation in beef cattle
As a result of the project it is now clear that a diagnostic test which had not been validated due to lack of suitable samples could now be submitted to the Sub Committee on Animal Health Laboratory Standards (SCAHLS) for approval for use in the national JD control program: the direct faecal PCR test. Additional validation of this test was recommended by the JD Research Advisory Group to provide better estimates of sensitivity and specificity. This was due to there being only a low number of samples of suitable quality from infected herds, and few culture positive samples, despite appropriate effort to obtain these in project P.PSH.0297.
During this project a total of 2472 faecal and blood samples were collected. Of the 2472 samples, 378 were selected for examination and were tested in both faecal culture and the new direct faecal PCR test. Of the 378 samples, 98 were positive in faecal culture and 111 were positive in faecal PCR. The selection of samples was successful for the purpose of validation of the PCR test. Remaining aliquots of the samples which were tested, as well as the samples which were not tested during this project were archived for future examination and represent a very valuable resource for BJD test development and validation, including in an active project P.PSH.0576.
The direct faecal PCR test will be a breakthrough for the beef cattle industry. Previously, faecal samples were collected, sent to a laboratory and 3 months would elapse before negative test results could be confirmed. For cattle sales this meant considerable forward planning and great inconvenience for the producer. Where culture was used to confirm a suspected herd infection, for example after positive or suspect ELISA test results, the long delay caused considerable additional anxiety for the producer. The new test overcomes these problems because it can provide results within a few days of receipt of samples at a laboratory. It will cost no more than culture. Furthermore it is suitable for testing pooled faecal samples, which enables a cheap method of herd testing, either to detect infection or to show that it is not present in herds in the Market Assurance Program. The test will also be suitable for environmental testing.
Final data will be submitted to SCAHLS in January 2012 for approval for use of the test in the National Johne’s Disease Program.
This page was last updated on 24/07/2017
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