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Title: Bovine brucellosis : a study of the serological aspects of the disease
Author: Nagy, Laszlo K.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1965
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Abstract:
A study of bovine brucellosis was carried out on a herd of mixed vaccination history with a view to evaluating the various methods of diagnosis used under field conditions in Great Britain. It was shown that the milk ring and whey agglutination tests were largely negative in calfhood-vaccinated brucella-free animals (85.1% and 96.1% respectively). In animals vaccinated as adults or repeat vaccinated, the milk ring test appears to be valueless as an indicator of field infection because of the very high percentage of falsely positive results (47.7%). The whey agglutination test was shown to be as valuable in these cattle as in calfhood-vaccinated cows, provided that the level of significance of whey agglutinins was taken as 1:10. The whey agglutinin titres appear to be influenced by the stage of lactations and there is a rise in the percentage of positives with advancing gestation. It is suggested that the milk ring and whey agglutination tests on them are of little value in the detection of infected animals since these are detected more readily by repeat serum agglutination test alone, but they are valuable as moderators in cases where the serum agglutination test gave doubtful results. The results of the vaginal mucus agglutination test indicate that tis value is very similar to that of the whey agglutination test in that it does not help significantly in the detection of infected animals but does serve to indicate absence of brucella infection in animals giving doubtful serum agglutinin titres. Over-age vaccination of cattle with Br.abortus S19 diminishes the value of the serum agglutination test to a considerable degree. The vaccinal serum agglutinin titre persists much longer in adult-vaccinated animals than in calfhood-vaccinated stock. There is a marked tendency for the serum titres of adult and also of calfhood-vaccinated animals, born and vaccinated in an infected environment, to show fluctuation of serum titres. One result of this fluctuation is that, on occasions, non-infected animals may show higher titres than animals known to be infected with Br.abortus. It is suggested that the too rigid application of the accepted criteria to the interpretation of serum agglutinin titres of adult-vaccinated cows may cause the disposal of many cows which may never constitute any danger for the rest of the herd. The examination of milk and vaginal mucus samples may be of real value in this situation. The results of cultural and biological examination of milk, vaginal mucus, post-partum and autopsy specimens indicated that the time and expense involved in these tests, purely for the diagnosis of brucella infection, is not proportionate to their value. However, where maximum safety is required their use may be justified.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.776705  DOI: Not available
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