Evaluation of a comparative intradermal tuberculin test in California dairy cattle :
Nine herds containing 2361 cattle were tested with mammalian and avian tuberculins from Agricultural Research Service (ARS). Injections were made at the cervical and the caudal fold sites and were observed at 48, 72 and 96 hours after injection. Sensitivity to tuberculin was demonstrated in 515 (21.8 per cent) cattle, and 31 of the 515 were confirmed as tuberculosis "positive", either by laboratory findings or by the presence of typical tuberculosis lesions (or both). Computer-based discriminant analysis of the sizes of reactions to the 2 tuberculins correctly classified 20 of the 31 tuberculosis-positive cattle (false negatives = 35.5 per cent) and 120 of the 165 tuberculosis-negative cattle (false positives = 25.9 per cent) used as a comparison group. According to the British system for classification of tuberculin reactions and a graphic comparative system of classification (described in the report), the percentage of false positives and the total number of cattle required for postmortem examination were decreased, but the percentage of false negatives was increased to 41.9 per cent. Both of these methods were better than the ARS procedure for classifying cattle on the basis of tuberculin reactions. Skin lesions were equally prevalent in the positive and the negative classes. With both tuberculins, the cervical test site was shown to be more sensitive than the caudal fold test site. Continued use and analysis of the comparative test are proposed
| Main Authors: | , , |
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| Format: | biblioteca |
| Language: | eng |
| Published: |
Mar
|
| Subjects: | TUBERCULINA, INMUNOSENSIBILIZACION, REACCIONES ALERGICAS, PRUEBA TUBERCULINICA, RESPUESTA INMUNOLOGICA, LESIONES, MYCOBACTERIUM, BACTERIOSIS, TUBERCULOSIS BOVINA, GANADO DE LECHE, INSPECCION POSTMORTEM, PROCESAMIENTO DE DATOS, CALIFORNIA, ESTADOS UNIDOS DE AMERICA, |
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| Summary: | Nine herds containing 2361 cattle were tested with mammalian and avian tuberculins from Agricultural Research Service (ARS). Injections were made at the cervical and the caudal fold sites and were observed at 48, 72 and 96 hours after injection. Sensitivity to tuberculin was demonstrated in 515 (21.8 per cent) cattle, and 31 of the 515 were confirmed as tuberculosis "positive", either by laboratory findings or by the presence of typical tuberculosis lesions (or both). Computer-based discriminant analysis of the sizes of reactions to the 2 tuberculins correctly classified 20 of the 31 tuberculosis-positive cattle (false negatives = 35.5 per cent) and 120 of the 165 tuberculosis-negative cattle (false positives = 25.9 per cent) used as a comparison group. According to the British system for classification of tuberculin reactions and a graphic comparative system of classification (described in the report), the percentage of false positives and the total number of cattle required for postmortem examination were decreased, but the percentage of false negatives was increased to 41.9 per cent. Both of these methods were better than the ARS procedure for classifying cattle on the basis of tuberculin reactions. Skin lesions were equally prevalent in the positive and the negative classes. With both tuberculins, the cervical test site was shown to be more sensitive than the caudal fold test site. Continued use and analysis of the comparative test are proposed |
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