ABSTRACT
BACKGROUND: Marek's disease is a chicken lymphoproliferative viral illness. As new viruses emerge, vaccination immunity is being broken and hence pathogenecity assessment and vaccine evaluation related to the pathogen is critical for developing vaccine immunity in the field. METHODS: An experimental investigation was conducted to determine the pathogenicity of field isolates against Marek's disease in antibody-free chicks and to assess the protective efficacy of the Marek's disease vaccination. The viral isolates in question were discovered during an outbreak investigation for a previous study. The pathogenicity and effectiveness trial used a complete random design. RESULTS: In the pathogenicity trial, chickens inoculated with Bishoftu and Mojo field isolate had lower body weight 77.7±3.757 and 78.15±1.95 g at 10 dpi, respectively, when compared to un-inoculated controls, 89.85±3.838 g at 10 dpi. Incidence of early mortality syndrome (35% and 25%), lymphoma (53.8% and 40%), and overall mortality (50% and 45%) between Bishoftu and Mojo isolates, respectively, was discovered. Vaccinations with Herpes virus of turkey challenged chickens were provided complete protection against Marek's disease. CONCLUSION: Based on the findings in pathogenecity assessment experimental trials, Bishoftu and Mojo isolates were designated as virulent Marek's disease viruses. Regular vaccinations with Herpes virus of turkey vaccine and supported by biosecurity measures in poultry farms are important to prevent the disease.
ABSTRACT
A cross-sectional study was conducted between December, 2013, and May, 2014, to determine the prevalence and antibiotic resistance feature of Salmonella isolated from broilers slaughtered in Debre Zeit and Modjo towns, Ethiopia. A total of 384 caecal content samples were collected for microbiological examination following the standard techniques and procedures outlined by the International Organization for Standardization to isolate Salmonella. The sensitivity of the isolates subjected to nine antimicrobials was tested by the Kirby-Bauer disk diffusion method. The overall prevalence of Salmonella was 14.6%, and its occurrence differ significantly by farm (p < 0.05). The occurrence of the bacteria was not statistically different in the midland (15.2%) and lowland (13.3%) (p > 0.05) and between males (13.5%) and females (15.6) (p > 0.05). Of the 50 isolates, 48 were resistant to at least one drug. Multidrug resistance was recorded in 43 (86.0%) of the isolates. The study demonstrated considerable prevalence and high antimicrobial resistant Salmonella in exotic chicken and indicates the potential importance of chickens as source of foodborne salmonellosis and multiple antimicrobial resistance of Salmonella. Improving the hygienic practice of farms could help to reduce the occurrence of Salmonella in farms. Further studies are needed to describe the risk factors associated with the emergence of drug-resistant Salmonella in chicken.
