Epidemiological insights into fowl adenovirus, astrovirus, and avian reovirus in Brazilian poultry flocks: A cross-sectional study

This study conducted a comprehensive survey of Fowl Adenovirus (FAdV), Astrovirus (CAstV), and Avian Reovirus (ARV) in Brazilian poultry, aiming to understand their epidemiological aspects. A total of 1,988 commercial flocks were analyzed across various Brazilian states, resulting in 4,568 analyses. The findings indicated a 25.5 % positivity rate among flocks showing suggestive symptoms, with at least one virus detected in all industrial poultry-producing states. Single-agent infections were more prevalent than co-infections. Among states with over 100 flocks analyzed, the highest FAdV prevalence was found in Santa Catarina and Paraná, while Rio Grande do Sul and Goiás showed the highest CAstV prevalence. For ARV, São Paulo, Rio Grande do Sul, Paraná, and Goiás had the highest rates. FAdV or CAstV were primarily isolated from the intestine (79.69 % and 78.17 %, respectively), whereas ARV was often detected in both the intestine (58.61 %) and tendons (48.01 %). All positive flocks were under 70 days old; chicks younger than 14 days were more likely to test positive for CAstV, while those aged 15 to 70 days showed higher positivity for ARV or co-infections of FAdV and ARV. Notably, strong associations were found between leg problems and ARV (OR = 5.33) or mixed infections (OR = 10.60), as well as between white chicks and CAstV (OR = 5.15) and diarrhea linked to CAstV (OR = 7.27). Regarding gross lesions, significant associations included gizzard erosion with FAdV (OR = 8.20), liver lesions with FAdV (OR = 4.28), and arthritis with ARV (OR = 2.84). In 2023, FAdV strains identified included Aviadenovirus A (A. ventriculi), B (A. quintum), D (A. gallinae), and E (A. hepatitidis). This research underscores the substantial impact of these viruses on Brazilian poultry farming and emphasizes the urgent need for enhanced surveillance and control measures to mitigate their effects on poultry production.