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This article was published in 1992
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Comparison of the Gamma-Interferon Assay and SID Tests for the Diagnosis of Bovine Tuberculosis in a Mudgee Beef Herd
HV Grant-Frost District Veterinarian, MUDGEE
HISTORY
This herd had a history of TB going back to 1982. Between March 1982 and November 1984 a total of 2723 SID tests were carried out, with removal of 36 positive reactors of which 22 had lesions at autopsy, and were M. bovis culture positive. No positive reactors were found after E6 in May 1983, when quarantine was lifted.
A further traceback occurred in February 1990 when a yearling heifer slaughtered at Blayney abattoir was found to have large granulomatous lesions in several organs and lymph nodes. TB was confirmed by culture in May 1990.
Field testing began on 20 February 1990. 208 head were SID tested and blood samples taken concurrently. Bloods were consigned same day to RVL Orange which had made all necessary preparations for completion of the GIFN. The remainder of the herd, a further 208 head, was tested on 17 March after a decision had been made for the valuation and slaughter of the herd.
TEST RESULTS
20.02.90
| GIFN+ | SID+ | CULTURE | |
|---|---|---|---|
| MOB 1 | 3 | 0 | 0 |
| MOB 2 | 14 | 17 | 18 |
| MOB 3 | 2 | 1 | 1 |
| МОВ 4 | 1 | 1 | 1 |
| TOTAL | 20 | 19 | 20 |
* 4 false + ve GIFN
4 false - ve GIFN
*1 false - ve SID (this animal also false - ve GIFN)
O false + ve SID
* Mob 2 was a group of 17 old cows, all of which were infected, and four younger Cows, none of which reacted to either test. They were slaughtered along with their cohorts, one being found infected i.e. the one animal falsely negative to both SID and GIFN.
17.03.90
| GIFN+ | SID+ | CULTURE | |
|---|---|---|---|
| 208 Head | 6 | 7 | 5 |
* 1 false + ve GIFN
O false - ve GIFN
* 5 false + ve SID
3 false - ve SID
SUMMARY
316 cattle tested with both SD and GIFN.
25 infected animals, one failing to react to either test.
5 false + ve GIFN
4 false - ve GIFN
5 false + ve SID
4 false - ve SID
REFERENCES
Wood et al. (1991) Aust. Vet. J. 68:9:286.
Everett (1990) NSW Agriculture memo.