TY - JOUR
T1 - Utility of the Intradermal Skin Test in a Test-and-Cull Approach to Control Bovine Tuberculosis
T2 - A Pilot Study in Ethiopia
AU - Lakew, Matios
AU - Srinivasan, Sreenidhi
AU - Mesele, Beruhtesfa
AU - Olani, Abebe
AU - Koran, Tafesse
AU - Tadesse, Biniam
AU - Mekonnen, Getnet Abie
AU - Almaw, Gizat
AU - Sahlu, Temertu
AU - Seyoum, Bekele
AU - Beyecha, Kebede
AU - Gumi, Balako
AU - Ameni, Gobena
AU - Ashenafi, Hagos
AU - Bakker, Douwe
AU - Kapur, Vivek
AU - Gebre, Solomon
N1 - Funding Information:
All reagent and salary/per diem expenses were supported by NAHDIC's internal funds. The other expenditure associated with culling of reactor animals was covered by Alage Agricultural Technical and Vocational Education Training (ATVET) College. The cost for the fifth-round testing was covered by Accelerating Bovine Tuberculosis Control in Developing Countries (ABCD) project which is supported by a grant (OPP1176950) from the Bill & Melinda Gates Foundation and the U.K. Department for International Development to the Pennsylvania State University. TB
Publisher Copyright:
Copyright © 2022 Lakew, Srinivasan, Mesele, Olani, Koran, Tadesse, Mekonnen, Almaw, Sahlu, Seyoum, Beyecha, Gumi, Ameni, Ashenafi, Bakker, Kapur and Gebre.
PY - 2022/3/7
Y1 - 2022/3/7
N2 - Bovine tuberculosis (bTB) is one of the top three, high-priority, livestock diseases in Ethiopia and hence, the need for evaluation of potential control strategies is critical. Here, we applied the test-and-segregate followed by cull strategy for the control of bTB in the intensive Alage dairy farm in Ethiopia. All cattle reared on this farm were repeatedly skin tested using the Comparative Cervical Tuberculin (CCT) test for a total of five times between 2015 and 2021. During the first (October 2015) and second (March 2017) rounds of testing, all reactor animals (>4 mm) were culled, while those that were deemed as inconclusive (1–4 mm) were segregated and retested. At retest, animals with CCT >2 mm were removed from the herd. In the third (December 2017) and fourth (June 2018) rounds of tuberculin testing, a more stringent approach was taken wherein all reactors per the severe mode of CCT test interpretation (>2 mm) were culled. A final herd status check was performed in May 2021. In summary, the number of CCT positives (>4 mm) in the farm dropped from 23.1% (31/134) in October 2015 to 0% in December 2017 and remained 0% until May 2021. In contrast, the number of Single Cervical Tuberculin (SCT) test positives (≥4 mm) increased from 1.8 to 9.5% (from 2017 to 2021), indicating that CCT test might not be sufficient to effectively clear the herd of bTB. However, a more stringent approach would result in a drastic increase in the number of false positives. The total cost of the bTB control effort in this farm holding 134–200 cattle at any given time was conservatively estimated to be ~US$48,000. This, together with the need for culling an unacceptably high number of animals based on skin test status, makes the test-and-cull strategy impractical for nationwide implementation in Ethiopia and other low- and middle-income countries (LMICs) where the infection is endemic. Hence, there is an increased emphasis on the need to explore alternate, affordable measures such as vaccination alongside accurate diagnostics to help control bTB in endemic settings.
AB - Bovine tuberculosis (bTB) is one of the top three, high-priority, livestock diseases in Ethiopia and hence, the need for evaluation of potential control strategies is critical. Here, we applied the test-and-segregate followed by cull strategy for the control of bTB in the intensive Alage dairy farm in Ethiopia. All cattle reared on this farm were repeatedly skin tested using the Comparative Cervical Tuberculin (CCT) test for a total of five times between 2015 and 2021. During the first (October 2015) and second (March 2017) rounds of testing, all reactor animals (>4 mm) were culled, while those that were deemed as inconclusive (1–4 mm) were segregated and retested. At retest, animals with CCT >2 mm were removed from the herd. In the third (December 2017) and fourth (June 2018) rounds of tuberculin testing, a more stringent approach was taken wherein all reactors per the severe mode of CCT test interpretation (>2 mm) were culled. A final herd status check was performed in May 2021. In summary, the number of CCT positives (>4 mm) in the farm dropped from 23.1% (31/134) in October 2015 to 0% in December 2017 and remained 0% until May 2021. In contrast, the number of Single Cervical Tuberculin (SCT) test positives (≥4 mm) increased from 1.8 to 9.5% (from 2017 to 2021), indicating that CCT test might not be sufficient to effectively clear the herd of bTB. However, a more stringent approach would result in a drastic increase in the number of false positives. The total cost of the bTB control effort in this farm holding 134–200 cattle at any given time was conservatively estimated to be ~US$48,000. This, together with the need for culling an unacceptably high number of animals based on skin test status, makes the test-and-cull strategy impractical for nationwide implementation in Ethiopia and other low- and middle-income countries (LMICs) where the infection is endemic. Hence, there is an increased emphasis on the need to explore alternate, affordable measures such as vaccination alongside accurate diagnostics to help control bTB in endemic settings.
UR - http://www.scopus.com/inward/record.url?scp=85127299143&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85127299143&partnerID=8YFLogxK
U2 - 10.3389/fvets.2022.823365
DO - 10.3389/fvets.2022.823365
M3 - Article
C2 - 35330613
AN - SCOPUS:85127299143
SN - 2297-1769
VL - 9
JO - Frontiers in Veterinary Science
JF - Frontiers in Veterinary Science
M1 - 823365
ER -