Epidemiological investigation of fowl adenovirus (FAdV) infections in ducks and geese in Shandong Province, China.

RESEARCH HIGHLIGHTS: Samples of suspected FAdV-infected waterfowl from farms in Shandong Province were collected from 2019 to 2022.Single infections with FAdV were less frequent than mixed infections.477 out of 792 samples (60.23%) tested positive for FAdV nucleic acids.Detection rate of FAdV was 65.47% in fattening duck farms, 55.73% in breeder duck farms and 54.55% in fattening geese farms.

Pathogenicity of duck circovirus 1 in experimentally infected specific pathogen-free ducks.

Ducks infected with duck circovirus (DuCV) show symptoms such as feather loss, growth retardation and low body weight in the flock. The virus induces immunosuppression and increases the prevalence of infection with other pathogens. However, most studies on duck circovirus were focused on coinfection, and fewer studies had been conducted on the pathogenicity of duck circovirus alone. The aim of the present study was to investigate the pathogenesis of DuCV-1 in experimentally infected specific pathogen-free ducks. In this study, we sequenced the whole genome of a strain of duck circovirus and identified the virus genotype as DuCV-1b. This strain of duck circovirus was named SDLH(OR567883). Animal pathogenicity experiments were then conducted, wherein specific pathogen-free ducks were infected by mucosal injection and abdominal injection. Infected ducks were sampled for 4 consecutive weeks after infection and showed symptoms of dwarfism. We further examined the replication of DuCV-1 in the ducks. The highest virus titers in the 2 infection groups were found in the liver and spleen, with different results for the different routes of infection. Pathological sections of duck organs were made and it was found that organs such as the liver and spleen were damaged by DuCV-1. In conclusion, our experimental results indicate that DuCV-1 can infect ducks individually and cause widespread organ damage in infected ducks.