Browsing by Author "Abebe Fromsa"

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    Bovine Tuberculosis in Central Ethiopia: Epidemiology, BCG Efficacy in Reducing Transmission, and Performance of Defined Antigen Cocktails for Differentiating Infected from Vaccinated Crossbred Cattle
    (Addis Abeba University, 2025) Abebe Fromsa; Prof. Balako Gumi
    : Bovine tuberculosis (bTB) is a threat to animal health, the livestock economy,food security, and human safety. Although animal level prevalence ranges from 25% to 39% and herd prevalence exceeds 50% in intensive dairy farms in central Ethiopia, control measures are lacking. The conventional test-and-slaughter strategy is resource-intensive and unaffordable for low- and middle-income countries (LMICs) such as Ethiopia. This necessitates a cost-effective alternative control strategy. Bacillus Calmette-Guérin (BCG) vaccination may constitute a cost-effective approach to control bTB in LMICs and regions with wildlife reservoirs. A meta-analysis of previous BCG vaccine evaluation studies demonstrated limited overall direct efficacy of 25% and additional partial protection by reducing the frequency and severity of disease pathology. Whether this partial protective effect translates into indirect protection through a reduction in the infectiousness of vaccinated animals has not been evaluated. Besides, since the interference of the BCG vaccine with the tuberculin skin testing is a major hindrance to the deployment of BCG vaccination for cattle, there is also a need to adopt a diagnostic test that differentiates infected from vaccinate animals (DIVA). On top of these, a slaughterhouse survey was conducted to identify hotspots of bTB in central Ethiopia to prioritize targeted control measures. Objectives: The objectives of this study include to quantify the direct and indirect efficacies of BCG vaccination in crossbred cattle, evaluate the diagnostic performance of defined peptide antigen cocktails (ESAT-6, CFP10, and Rv3615c) in differentiating infected from vaccinated animals (DIVA), assess the practical implications of routine vaccination on the spread of bTB in the emerging dairy sector, and estimate the prevalence and identify the causative agents of bTB in cattle in central Ethiopia. Methodology: A natural transmission experiment was conducted using a crossover design in two phases, each lasting for one year to evaluate both the direct and indirect effects of BCG vaccination in reducing the transmission of bTB. Sixty-seven unvaccinated control and 67 vaccinated calves were exposed to an equal number of respective seeders eight weeks postvaccination and maintained in contact for twelve months during each phase. Sixty-five unvaccinated control and 62 vaccinated calves underwent postmortem tests. Skin and IGRA tests were conducted using tuberculin and DIVA antigen cocktails every four and two months, respectively. For efficacy evaluation, calves that ever tested positive for DIVA antigens in the IGRA test were considered infected and potentially infectious. Then a mechanistic transmission model calibrated using within-herd basic reproduction number (Ro) and empirical cattle movement data was used to explore the long-term effect of routine BCG vaccination in controlling bTB in the Ethiopian dairy sector. The performance of DIVA antigen cocktails was compared to tuberculin in both IGRA and skin test formats. A slaughterhouse survey was conducted in Central Ethiopia to assess the prevalence, risk factors, and causative agents of bTB. The causative agents were identified using multiplex quantitative PCR (m-qPCR) in all culture-positive samples. Result: The study found a significantly lower total visible lesion score in vaccinated animals compared to unvaccinated controls and a reduction in bTB transmission of 74% (95% CI: 46– 89%) among vaccinated animals compared to unvaccinated controls. The direct efficacy was 58% (95% CI: 34%–73%). The combined direct and indirect effects resulted in a total vaccine efficacy of 89% (95% CI, 74–96%). The estimated Ro, representing the average number of secondary cases per infectious individual was 3.1 (95% CI: 2–4) in unvaccinated group while it was 0.3 (95% CI: 0.1–0.7) in the vaccinated group. A mechanistic transmission model suggests that routine neonatal calf vaccination has the potential to reduce the average population Ro to below 1 within 10 years, presenting significant opportunities for the control and elimination of bTB in cattle. Eight weeks after vaccination, but before exposure to infected seeder animals, the specificities of IGRA and skin test-based defined antigen cocktails were 98.5% and 94.0%, respectively. However, at the end of the experiment, the sensitivities of these tests were 46% and 47%, respectively, which were similar with 45% sensitivity of the comparative tuberculin test (CCT). A slaughterhouse survey revealed the ongoing challenge of bTB in Central Ethiopia, with a prevalence of 2.3% bTB-related lesions and an eleven-fold greater risk in crossbred cattle than in local zebu cattle. All mycobacterial species isolated from experimental and slaughterhouse cattle were identified as M. bovis, except for two cases from the slaughterhouse. One of these cases exhibited co-infection with M. bovis and M. tuberculosis, while the other was co-infected with M. bovis and M. caprae. However, no positive M. orygis was detected in any of culture-positive samples. Conclusions: The study revealed previously unrecognized superior indirect effects of BCG on bTB transmission compared to its direct protective effect against infection. Scenario analyses using mechanistic models indicate that BCG vaccination may enable effective control of bTB and contribute to elimination efforts. DIVA antigens demonstrated high specificity in BCGvaccinated cattle, highlighting their importance for potential integration into BCG vaccination programs for bTB control. These findings hold significant implications for resource-limited settings where the test-and-slaughter strategy is not feasible, while vaccination combined with DIVA testing remains a beneficial and effective approach. The higher risk of bTB in crossbred cattle underscores the necessity for targeted interventions, particularly in crossbred cattle predominantly raised in intensive dairy production systems.
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    Case Reports on Common Surgical Procedures, Techniques and Its Outcome on Domestic Animals in and around Bishoftu Town, Ada’a District, East Shoa Zone, Ethiopia
    (2019-06) Jiregna Dugassa; Abebe Fromsa
    Livestock are the back bone of growth and development of a particular country of the world especially where majority of people rely on it as main source of income, daily livelihood and draught purpose. However this vast and valuable sector can be affected by multifaceted problems and constraints which can directly and/or indirectly hamper the production and productivity of the animals. Among these factors, poor and unsatisfactory coverage of veterinary services particularly veterinary surgical management of different deformities, injuries and ailment of various origins is one of the main problems in Ethiopia. So the surgical case reports presented in this study were compiled from surgical cases presented and performed to show the significance of surgical procedures and techniques on the outcomes related to recovery from abnormality. The procedures and techniques included in these case reports were performed on domestic animals brought to Veterinary Teaching Hospital, Donkey Sanctuary and Dire Veterinary Clinics with different ailments requiring surgical management during October, 2018 to June, 2019 G.C. On presentation, history, general physical examinations, clinical and laboratory findings were thoroughly assessed to determine the type of treatment and surgical intervention required. When the animal was found to require specific surgical treatment; each and every animal was well prepared for aseptic procedures and anesthetics preoperatively, before surgical procedure depending on animal species and type of surgical procedure to be conducted. The prescribed specific surgical procedure for each specific condition was performed using appropriate technique, suture material and patterns based on the requirement of the body site. After surgery, each and every animal patient was followed postoperatively and surgical complications and recovery outcomes were recorded. In this study a total of 27 animals including 33.33% (9/27) small animals and 66.67% (18/27) large animals were operated on different parts of their body at different places. Of all the operated animals, 96.30% (26/27) were recovered and cured whereas 3.70% (1/27) was died. This finding shows that surgical intervention performed by well trained veterinary surgeon under proper aseptic technique is crucial to save significant number of animals affected by life threatening conditions.
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    Compiled Case Reports on Different Surgical Cases: Their Procedures, Outcomes and Encountered Complications in Different Domestic Animals in and around Bishoftu, Oromia, Ethiopia
    (Addis Abeba University, 2024) Maranata Milkias; Abebe Fromsa
    Livestock is an indispensable component of Ethiopian agriculture, with live animals and their byproducts contributing approximately 40% of the agricultural economy. Disease significantly impacts livestock productivity by reducing growth rates, reproductive performance, and milk production while increasing mortality rates and economic losses. Surgical interventions play a critical role in treating various diseases and conditions in livestock, thereby enhancing their health, productivity, and overall well-being. Complications following surgery at the incision site can include swelling, local infection, sinus formation around sutures, hematoma (blood accumulation), drainage from the incision site, incisional opening (dehiscence), and hernia formation. The present case report was compiled between September 2023 and May 2024 GC aimed to document a variety of surgical conditions affecting different body systems in domestic animals. The cases were referred to or directly presented to esteemed institutions such as Professor Fiseha Gebreab Memorial Veterinary Teaching Hospital, Society for the Protection of Animals Abroad, Donkey Sanctuary Veterinary Clinic, and Amanuel Veterinary Clinic located in Dire. The objective was to analyze the outcomes of these surgical interventions, their procedures and encountered complications. All the cases presented in this study were thoroughly examined to determine the organ or system that was affected. The animal's medical history, clinical observations, and laboratory results were meticulously documented in the patient record format. Animals with urgent surgical conditions underwent premedication, aseptic preparation, and anesthesia. They subsequently received specific surgical treatment and corrections, followed by adequate postoperative care and routine follow-up. A total of twenty-one cases were handled, 13 out of 21 (61.90%) were large animals and 8 out of 21(38.01%) were small animals. 4 out of 21 (19.05%) cases died, while 17 out of 21 (80. 95%) animals recovered. Continued research and detailed documentation of surgical cases should be encouraged to build a robust database of case studies that can serve as valuable references for veterinary practitioners