Outbreak of fowl adenovirus FAV-E (serotype 8b) in broilers in Libya: A case report.

Background: Fowl adenovirus (FAV) is responsible for many disease conditions in poultry, leading to numerous economic impacts, including mortality, drop in egg production, and carcass condemnations. This is the first report on molecular characterization of FAV-E (serotype 8b) in Libya. Case Description: During January 2023, three broiler flocks had increased mortality up to 25%-50%. Paleness and haemorrhages in the liver appeared in birds that were 23 to 27 days old. The total number of birds was 12,000, 16,000, and 22,000 in the first, second, and third flock, respectively. Ten Samples from the liver and kidneys were collected for histopathological examination from each flock, and liver, spleen, and caecal tonsils were collected for DNA extraction, Real-time polymerase chain reaction, and sequencing. Histopathological examination of the liver revealed hemorrhages, fatty changes, and coagulative necrosis, the presence of intranuclear eosinophilic inclusion bodies in hepatocytes, and karyorrhexis of the nucleus and multiple perivascular infiltration of pleomorphic lymphocytes. The kidney showed subcapsular hemorrhages and infiltration of lymphocytes and inflammatory cells, focal necrosis, and glomeruli enlarged with hyper-cellularity. All tested samples were positive for FAV, and sequencing confirmed the FAV-E (serotype 8b) strain, which is 99.53% identical to some isolates from Turkey. Conclusion: FAV-E (serotype 8b) strain is circulating in broiler flocks, leading to high mortality. Further research is required to determine the epidemiology of the disease in the country and to investigate the presence of other strains of fowl adenovirus in order to introduce the best vaccine.