Browsing by Author "Debebe Ashenafi"

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    Comparative Study on the Antibody Response of Infectious Bursal Disease Immune-Complex and Live Vaccines and Survey on Overall Disease Status Progress and Vaccine Management in Commercial Poultry Farms in Bishoftu Town, Central Ethiopia
    (Addis Ababa University, 2024) Nanoshe Taye; Debebe Ashenafi
    The poultry production sector is vital for providing sustenance and enhancing food security in developing nations such as Ethiopia. However, this sector faces significant challenges, including infectious bursal disease (IBD). Evaluating the effectiveness of different vaccines for IBD is crucial for improving vaccination protocols and disease management. This study, conducted from November 2023 to May 2024, involved a controlled experimental study on 100 day-old chickens and a questionnaire survey of 93 poultry farms in Bishoftu town. The objectives were to gain insights into disease and vaccine management and to compare the immune response of chickens to various vaccines. The experimental study utilized a stratified randomized controlled trial with four groups of 25 chickens each. Group 1 received the CEVAC® TRANSMUNE vaccine, Group 2 received CEVAC® GUMBO L, Group 3 received IBD VIRUS LC – 75, and Group 4 served as a control. Vaccines were administered according to the manufacturer's recommendations. Blood samples (2 ml per chick) were collected on days 7, 14, 21, 28, 35, and 42 post-vaccination. Serum samples were analyzed for antibody response using a commercial indirect ELISA kit, and data were processed with STATA software. Survey results indicated that most respondents (64.52%) had 1 to 5 years of experience in the sector, and 50.54% were familiar with IBD and its impact. Key factors in vaccine selection included efficacy (45.16%), availability (19.35%), and cost (18.28%). Antibody titers produced by the vaccines varied: Trans-immune showed mean titers of 1298.814, 183.868, 38.864, 6280.42, 4424.76, and 6129.617 on days 7, 14, 21, 28, 35, and 42, respectively; Gumbo L showed titers of 21.46286, 2581.282, 3363.248, 3156.71, 3400.04, and 5973.526; and IBD LC-75 showed titers of 22.916, 642.136, 5270.4, 5653.071, 5793.221, and 6520.836 on the same days. All vaccines induced protective antibody titers, despite differences in the timing of responses. Continuous and updated surveillance on vaccine types and management practices is essential for effective disease control. Evaluating the immune response to vaccines in the presence of the challenge virus is also critical
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    Molecular Detection and Virus Isolation of Infectious Bursal Disease Virus from Outbreak Cases in Selected Districts of Central Ethiopia
    (Addis Abeba University, 2023) Endeshaw Mulu; Debebe Ashenafi
    Infectious bursal disease also called Gumboro is a highly contagious viral disease of young chickens that causes significant economic losses in the poultry industry worldwide. The disease is caused by the Infectious bursal disease virus (IBDV), which belongs to the genus Avibirnavirus of the family Birnaviridae, double strand RNA virus with a non-enveloped, icosahedral capsid with bi-segmented genome. An outbreak based cross sectional study was conducted in poultry farms located in Bishoftu, Dukem, Modjo, Gelan and Tulu-Dimtu, central Ethiopia, from December 2022 to May 2023 for molecular detection and isolation of infectious bursal disease virus (IBDV) from outbreak cases. Purposive sampling technique and a semi-structured questionnaire was employed on selected farm owner and attendants to assess management and vaccination practices of the farms. Pools of bursal samples were collected, and virus isolation and reverse transcriptase-polymerase chain reaction (RT-PCR) were performed to confirm the outbreak cases. From the total nineteen farms surveyed 47.37% vaccinate their chickens against IBDV. Only 21.05% vaccinate according to manufacturer‟s protocol and 78.95% revealed lack of knowledge about biosecurity practice, and 63.16% had poor hygienic condition, while only 26.32% practice regular cleaning and disinfectants. Out of a total of 4 bursal suspensions collected and prepared from 19 poultry farm outbreaks, all were showed characteristic cytopathic effects starting on day two post infection after second passage on differentiated fibroblasts (CEF) cell lines. Of the seven pooled samples analyzed by RT-PCR, six of them were positive results. The results indicated that there is continuous presence of IBD in poultry farms in the country suggesting that current vaccine procedures and protocols as well as management practices may not be working properly. In conclusion, IBD has become the most devastating disease of chicken in central Ethiopia, with high economic lose. Hence, sequencing of the positive samples is much needed to know the circulating virus strains in the areas.
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    Outbreak Investigation and Molecular Characterization of Infectious Bursal Disease Virus in Poultry Farms at Modjo and Bishoftu Towns, Central Ethiopia
    (2020-06) Debebe Ashenafi; Gezahegn Mamo
    Infectious Bursal Disease (Gumboro disease) is a highly contagious viral disease of chickens with a worldwide prevalence, which is caused by infectious bursal disease virus, (genus Avibirnavirus, family Birnaviridae), infects chickens and is becoming serious threat and challenging to the emerging poultry industry in Ethiopia. Molecular characterization targeting the major capsid protein, viral protein 2, plays an important role in the identification of the various strains of infectious bursal disease virus, tracing back of the origin of the virus and in vaccine matching studies. An outbreak based cross sectional study was carried out from October 2019 to May 2020, with the main objectives of characterizing field strains of the virus from outbreak cases in poultry farms at Bishoftu and Modjo towns, Central Ethiopia. A total of six farms were addressed during the study time and four to five chickens were opened per outbreak from each farm. Smear samples for molecular analysis and pooled samples for culture were collected on Flanders Technology Associates cards and in universal bottles containing viral transport medium, respectively. Virus isolation and reverse transcriptase-polymerase chain reaction and sequencing were performed to confirm the outbreak cases. Bursal suspensions were prepared for both cell culture and molecular analysis. Up on visualizations of the DF-1 cell lines used for cell culture after two passages, cytopathic effects: cell swelling, cell rounding, detachment and floating, were observed. Up on characterization of viral protein 2 region of the virus using reverse transcriptase polymerase chain reaction and sequencing, both vaccinal (six IBDV Genogroup 1) and field viral strains (five IBDV Genogroup 3) were detected. The current isolates made three clusters, namely, isolates identical to vaccinal strains ((Winterfield 2512-like) - CEVAC® IBD L)) and (Faragher 52/70 used in HVT+IBD vaccines), field strains identical to very virulent strains deposited in the Genbank, and isolates identical to vaccine strain manufactured and marketed by National Veterinary Institute, Ethiopia. The results indicate that, in addition to the continuous circulation of vvIBDV strains in the country, vaccinal strains are also reverting to their virulence being one of the causes for the investigated outbreaks. Therefore, further and sustained molecular characterization of the vaccinal and field IBDV strains is crucial as the virus is resistant and prone to change in its nucleotide sequences.