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Title: Epidemiology and immuno-pathology of bovine tuberculosis in Bos indicus and Bos taurus cattle in Ethiopia
Author: Ameni, Gobena
ISNI:       0000 0004 2670 9130
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
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A comparative study was conducted on the immunology, pathology, and epidemiology of bovine tuberculosis (TB) between 2004 and 2008 in Bos indicus (Arsi zebu) and Bos taurus (Holstein) in Ethiopia. A total of 153 cattle were used for immunological and pathological studies while 5,924 (500 from intensive farm and 5,424 from pasture) cattle were used for epidemiological studies. Comparative intradermal tuberculin (CIDT) test, gamma interferon (IFN-γ) test, lateral flow assay, multiple antigen print assay, enzyme-linked immuno-spot assay, interleukin-4 (IL-4) and IL-10 assays were used. IFN- γ responses to mycobacterial antigens were higher (for all: P<0.05) in Holstein than in Arsi zebu. But both breeds exhibited similar T cell and antibody specificities to mycobacterial antigens. Holstein kept indoors produced higher IFN-γ responses (for all: P<0.001) to mycobacterial antigens than those kept on pasture. Pathology of bovine TB was more severe (P<0.05) in Holsteins than in Arsi zebus as well as in Holsteins kept indoors (P<0.001) than in those kept on pasture. Pathology was localised in the digestive tract in cattle kept on pasture while it was localised in the respiratory tract in cattle kept indoors. At a cut-off >2mm, the sensitivity of CIDT was 69% (95% CI=58.5%, 79%) while it was 59% (95%CI = 49%, 69%) at a cut-off >4mm. Its specificity at both cut-off points was 97% (95%CI=89%, 100%). At cut-off >4mm, the apparent prevalence was 13.5% while it was 16.0% at cut-off >2mm, and was higher in Holstein than in Arsi zebus both at a cut-off >4mm (P<0.001) and cut-off >2mm (P<0.001). The true prevalence at a cut-off >4mm was 18.5% while it was 19.6% at a cut-off >2mm. In grazing cattle, of the total 40 isolates, 12 were specified as M. tuberculosis, 7 were M. avium subspecies while only a single isolate was M. bovis while in intensive husbandry, all the isolates (41) were confirmed to be a single strain of M. bovis (SB1176). All the strains of M. tuberculosis isolated from cattle had similar patterns with M. tuberculosis strains isolated from farmers in the area. In conclusion, Holsteins exhibited higher T cell responses to mycobacterial antigens, and higher prevalence and more severe pathology of bovine TB as compared to Arsi zebus. Besides, the results of this study suggest the transmission of M. tuberculosis between farmers and their cattle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available