Abstract
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.
Highlights
Bovine tuberculosis is a chronic, progressive, granulomatous, inflammatory disease of cattle caused by members of the Mycobacterium tuberculosis complex (MTBC) [1]
The 64 local Boran cattle were not tested in the previous round and a decision was made to include them in this round of testing as they were managed in close proximity from the main Alage herd and to avoid any resulting spillover of infection
The prevalence of bovine tuberculosis (bTB) in this round was found to be 4.6% (8/173), which was significantly lower than the prevalence observed in the first round (χ2 = 23.3; P < 0.0001)
Summary
Bovine tuberculosis (bTB) is a chronic, progressive, granulomatous, inflammatory disease of cattle caused by members of the Mycobacterium tuberculosis complex (MTBC) [1]. Most high-income countries have successfully controlled bTB based on test-and-slaughter of skin test-positive animals, alongside slaughterhouse surveillance, and trade and movement restrictions of affected herds. In most low- and middle-income countries (LMICs), the bTB prevalence is high, and implementation of a test-and-slaughter program is not affordable for both social and economic reasons and, as a result, the disease has continued to cause significant economic and public health impacts [4]. It is important to note that this is likely an underestimate due to the lack of cross-sectional, national-level surveillance programs, under-reporting and lack of laboratory confirmation of causative agents in LMICs where the infection is endemic in both human and bovine populations [5]. It is being increasingly recognized that eliminating TB in humans cannot be accomplished without first controlling bTB in cattle
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
