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Field evaluation of specific mycobacterial protein-based skin test for the differentiation of Mycobacterium bovis-infected and Bacillus Calmette Guerin-vaccinated crossbred cattle in Ethiopia.

Published version
Peer-reviewed

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Authors

Bayissa, Berecha 
Sirak, Asegedech 
Zewude, Aboma 
Gumi, Balako 

Abstract

Bovine tuberculosis (bTB) challenges intensive dairy production in Ethiopia and implementation of the test and slaughter control strategy is not economically acceptable in the country. Vaccination of cattle with Bacillus Calmette-Guerin (BCG) could be an important adjunct to control, which would require a diagnostic test to differentiate Mycobacterium bovis (M. bovis)-infected and BCG-vaccinated animals (DIVA role). This study describes an evaluation of a DIVA skin test (DST) that is based on a cocktail (DSTc) or fusion (DSTf) of specific (ESAT-6, CFP-10 and Rv3615c) M. bovis proteins in Zebu-Holstein-Friesians crossbred cattle in Ethiopia. The study animals used were 74 calves (35 BCG vaccinated and 39 unvaccinated) aged less than 3 weeks at the start of experiment and 68 naturally infected 'TB reactor' cows. Six weeks after vaccination, the 74 calves were tested with the DSTc and the single intradermal cervical comparative tuberculin (SICCT) test. The TB reactor cows were tested with the DSTc and the SICCT test. Reactions to the DSTc were not observed in BCG-vaccinated and unvaccinated calves, while SICCT test reactions were detected in vaccinated calves. DSTc reactions were detected in 95.6% of the TB reactor cows and single intradermal tuberculin positive reactions were found in 98.2% (95% confidence interval, CI, 92.1-100%). The sensitivity of the DSTc was 95.6% (95% CI, 87.6-99.1%), and significantly (p < .001) higher than the sensitivity (75%, 95% CI, 63.0-84.7%) of the SICCT test at 4 mm cut-off. DSTf and DSTc reactions were correlated (r = 0.75; 95% CI = 0.53-0.88). In conclusion, the DSTc could differentiate M. bovis-infected from BCG-vaccinated cattle in Ethiopia. DST had higher sensitivity than the SICCT test. Hence, the DSTc could be used as a diagnostic tool for bTB if BCG vaccination is implemented for the control of bTB in Ethiopia and other countries.

Description

Funder: The Defense Science and Technology Laboratory


Funder: Medical Research Council; Id: http://dx.doi.org/10.13039/501100000265


Funder: Economic and Social Research Council; Id: http://dx.doi.org/10.13039/501100000269


Funder: Department for International Development, UK Government; Id: http://dx.doi.org/10.13039/501100000278


Funder: Biotechnology and Biological Sciences Research Council; Id: http://dx.doi.org/10.13039/501100000268

Keywords

BCG vaccination, DIVA skin test, bovine tuberculosis, crossbred cattle, specific mycobacterial proteins, Animals, BCG Vaccine, Cattle, Cattle Diseases, Ethiopia, Female, Mycobacterium bovis, Tuberculin, Tuberculin Test, Tuberculosis, Bovine, Vaccination

Journal Title

Transbound Emerg Dis

Conference Name

Journal ISSN

1865-1674
1865-1682

Volume Title

Publisher

Hindawi Limited
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/L018977/1)
Biotechnology and Biological Sciences Research Council (BB/S013806/1)