A surge in fowl adenovirus (FAdV) causing inclusion body hepatitis (IBH) outbreaks has occurred in several countries in the last two decades. In Spain, a sharp increase in case numbers in broilers and broiler breeder pullets arose since 2011, which prompted the vaccination of breeders in some regions. Our retrospective study of IBH cases in Spain from 2011 to 2021 revealed that most cases were reported in broilers (92.21%) and were caused by serotypes FAdV-8b and -11, while cases in broiler breeder pullets were caused by serotypes FAdV-2, -11, and -8b. Vertical transmission was the main route of infection, although horizontal transmission likely happened in some broiler cases. Despite the inconsistent and heterogeneous use of vaccines among regions and over time, the number of cases mirrored the use of vaccines in the country. While IBH outbreaks were recorded year-long, significantly more cases occurred during the cooler and rainier months. The geographic distribution suggested a widespread incidence of IBH and revealed the importance of a highly integrated system. Our findings contribute to a better understanding of FAdV infection dynamics under field conditions and reiterate the importance of surveillance, serological monitoring of breeders, and vaccination of breeders against circulating serotypes to protect progenies.

The online version contains supplementary material available at 10.1038/s41598-025-33989-2.

Transmissible viral proventriculitis (TVP) and chicken proventricular necrosis virus (CPNV) affect the broiler industry globally and are emerging diseases of economic importance. Here, we present the findings of TVP from processed broiler carcasses in Argentina following marked condemnation at the processing plant. We studied a total of 122 abnormally presenting proventriculi at processing from 42-to-50-day-old, male Cobb500^™ broiler chicken carcasses from 11 farms belonging to the same company in 13 episodes of proventriculi–gizzards condemnation between December 2021 and April 2022. The proventriculi were enlarged and pale with a widened gastric isthmus. A histopathologic lesion score system was developed based on the presence of a combination of key microscopic findings, the distribution, and the severity of the lesions. Scoring of the affected proventriculi revealed 65% (79/122) with a score of 4, 23% (28/122) with a score of 3, and 12% (15/122) with a score of 2. Focal to multifocal immunoreactivity against the VP2-CPNV antigen within the necrotic glandular epithelial cells was noted in the affected proventriculi using immunohistochemistry. We found 84.4% (103/122) of the studied proventriculi with TVP lesions grossly and microscopically scored were positive for CPNV by RT-PCR. The sequencing results of the PCR product showed a high nucleotide sequence similarity (88.97%) to previously published VP1-CPNV sequences. We confirmed CPNV infection in most of the TVP affected proventriculi in all condemnation episodes at a broiler chicken processing plant in Argentina during the studied period. This study documents TVP associated with CPNV detection at processing plants in Argentina for the first time.

High pathogenicity avian influenza (HPAI) poses a significant threat to poultry. Some chickens show resilience to HPAI, but the mechanisms involved are poorly understood. In this study, we aimed to identify the biological mechanisms associated with resilience to HPAIV infection in chickens. Chickens were inoculated with H7N1 HPAIV and classified as susceptible or resilient based on clinical signs, mortality, histopathological lesions, AIV antigen detection in tissues, and viral shedding. Blood transcriptomic analysis revealed that genes from resilient chickens are involved in the integrin-mediated signaling pathway (ITGA5, ITGA6, ITGB1), as well as in adaptive (BTK, TEC) and innate (TRIM13, LCK, TICAM1) immune pathways. Plasma proteomic profiling revealed that ARF4, EIF4A2, and HNRNPAB (proteins involved in fundamental cellular processes) were less abundant in resilient chickens compared to both controls and susceptible birds. Our results suggest that early modulation of these pathways is associated with resilience to HPAIV and likely reflects early viral control or reduced systemic dissemination rather than the absence of infection.

The house sparrow ( Passer domesticus ), a ubiquitous but declining species, is a potential bridge host for introduction of avian influenza virus (AIV) into poultry farms. We investigated the influence of diet and urban vs rural habitat on susceptibility to and persistence of AIV infection. Wild captured sparrows were inoculated intrachoanally with H7N9 LPAIV (A/Anas crecca/Spain/1460/2008), while control birds received saline. Swab and blood samples collected on 0, 1, 3, 4, 7, 10 and 14 days post-inoculation (dpi), and vascular feathers (1, 7 dpi) from 25% of individuals per group were tested by real-time RT-PCR. Although clinical signs were mild or absent, unexpected mortality (8.3%, 3/36) occurred starting at 4 dpi in urban and 7 dpi in rural sparrows. Viral shedding was observed between 1 and 4 dpi and seroconversion was confirmed in both inoculated groups. Natural Avipoxvirus (APV) infection was evidenced in all experimental groups, by histology, PCR and sequencing. Three distinct APV lineages were detected in oral swabs from urban and rural control birds, on 1 dpi. APV prevalence was higher and persisted longer in LPAIV-infected sparrows, with APV detection overlapping the peaks of LPAIV shedding in both urban and rural birds. These results confirm that urban and rural sparrows are similarly susceptible to experimental H7N9 LPAIV infection. Increased prevalence and persistence of APV during LPAIV infection suggest interaction between these viruses. Such interactions may represent an ecologically relevant but often overlooked component of avian influenza epidemiology and should be considered when evaluating sparrows as potential bridge hosts.

Improving animal welfare is an important objective of the European Union’s Common Agricultural Policy, as well as national regulations and voluntary certification schemes. Drawing on research conducted within the BroilerNet project, this paper presents an assessment of the production and economic effects of good practices in broiler farming identified in 13 participating EU countries. The methodology involved defining key challenges related to animal welfare, health, and environmental impacts; identifying practices already applied under commercial conditions; conducting preliminary assessments by national expert panels; and selecting the most promising practices, referred to as Champions, for final economic evaluation. The assessment used gross margin analysis and budgeting techniques considering additional implementation costs and potential production benefits. Typical farm models representing different flock sizes were developed. The analysis of six Champions presented in the paper revealed varied outcomes depending on implementation costs, expected production benefits, and the assumptions adopted under optimistic and pessimistic scenarios. According to farmers’ observations, supported by the available literature, all assessed practices improved animal welfare. Financial benefits varied with implementation costs, achievable productivity gains, and production scale, with the smallest farms benefiting less. Given the generally low implementation costs, all assessed practices merit wider dissemination.