Fowl aviadenoviruses in Moroccan poultry: pathological characteristics and phylogenetic analysis of circulating fowl aviadenovirus strains from 2012 to 2024.

Abstract

Over the last decade, the emergence of aviadenovirus infections, namely inclusion body hepatitis (IBH) and gizzard erosion and ulceration syndrome (GEUS) has occurred in Morocco with significant losses to the poultry industry. In this work, 255 suspected flock cases of IBH and GEUS were assessed among various poultry production types in the country from 2012-2024. Macroscopic pathological changes in affected chickens included an enlarged, discoloured liver or a distended gizzard with haemorrhagic content and erosion/ulceration on the koilin layer. Microscopic findings revealed severe necrotic hepatitis, consistent with IBH, and/or necrotizing ventriculitis, which is characteristic of GEUS, with intranuclear viral inclusion bodies (INIB) in the hepatocytes or epithelial cells of the gizzard, which are attributable to fowl adenovirus (FAdV). The real-time PCR results revealed that 71% (182/255) of the suspected FAdV cases tested positive. The prevalence varied by poultry production type, with broiler farms being the most affected at 79% (144/194), followed by layer farms at 15% (28/42), breeder farms at 5% (9/13), and turkey farms at 1% (1/6). Sequencing of the isolates identified FAdV serotype 11 (species D) and serotype 8b (species E) in 22 and six cases of IBH, respectively. Additionally, FAdV serotype 1 (species A) and serotypes 8a and 8b (species E) were detected in nine and two cases of GEUS, respectively. These findings underscore the significant impact of fowl adenoviruses on the Moroccan poultry industry and highlight the need for continuous surveillance and targeted control interventions.Increase in FAdV infections (IBH and GEUS) in Morocco over past decade.FAdV-positive cases were mainly found in broiler farms (79%).Identification of FAdV-11 and 8b serotypes for IBH, and FAdV-1, 8a and 8b for GEUS.