Salmonella is a major threat to both human and animal health. However, the diversity and antibiotic resistance of animal-derived Salmonella and their association with human infections remain largely unexplored. In this study, Salmonella strains were isolated, identified, and sequenced from dead embryos and cloacal swab samples obtained from 278 large-scale duck farms in 11 cities in Shandong Province. The results show that a total of 57 Salmonella strains were isolated, with the dominant sequence types (ST) being ST17 (15/57) and ST19 (9/57), while the dominant serotypes were S. Indiana (15/57) and S. Typhimurium (11/57). Furthermore, genomic analysis has revealed the presence of prevalent antibiotic resistance genes (ARGs), which are often associated with co-transfer mechanisms. Over 52.63% of the strains were observed to carry two or more ARGs, especially one Salmonella strain that carried twenty-eight distinct ARGs. Furthermore, core genome multilocus sequence typing analysis (cgMLST) indicated that the 57 Salmonella strains may have a close relationship, which could be clonally transmitted among different cities. The results demonstrated a close relationship between the Salmonella strains identified in diverse geographical regions, suggesting that these strains may have been widely disseminated through clonal transmission. The mutation analysis reveals significant mutations at parC (T57S), gyrA (S83F), parC (S80R), gyrA (D87N), and gyrA (S83Y). These findings emphasize the necessity for monitoring and controlling Salmonella infections in animals, as they may serve as a reservoir for ARGs with the potential to affect human health or even be the source of pathogens that infect humans.

Avian reovirus (ARV), a highly pathogenic agent in poultry, causes severe economic losses through immunosuppression and secondary infections. Traditional diagnostic methods like reverse transcription quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) face limitations in resource-limited settings due to equipment dependency and prolonged processing. To address this, we developed a rapid, portable detection method integrating reverse transcription–recombinase-aided amplification (RT-RAA) with CRISPR/Cas12a. By targeting the conserved P17-coding region of the ARV S1 gene, this assay amplifies viral RNA isothermally (37 °C) within 20 min, followed by Cas12a-mediated collateral cleavage of fluorescent or lateral flow reporters for visual readout. The method achieved a sensitivity of 1 copy/μL, surpassing RT-qPCR (10 copies/μL), and completed detection in 40 min. Specificity tests against non-target pathogens confirmed zero cross-reactivity. Utilizing a portable incubator and low-cost visual tools, this platform eliminates reliance on thermocyclers and skilled personnel. Its field-deployable design enables on-site diagnosis, facilitating early ARV detection to mitigate outbreaks and economic losses in poultry farming. This study provides a paradigm shift in avian pathogen surveillance, combining speed, sensitivity, and accessibility for global agricultural and public health applications.

Salmonella enterica subsp. enterica serovar Gallinarum biovar pullorum (Salmonella pullorum) is an avian-specific pathogen that has caused considerable economic losses to the poultry industry. High endemicity, poor implementation of hygiene measures, and lack of effective vaccines hinder the prevention and control of this disease in intensively maintained poultry flocks. In recent years, the incidence of arthritis in chicks caused by Salmonella pullorum infection has increased. In this study, four Salmonella pullorum strains were identified from the livers, spleens, and joint fluids of Qingjiaoma chicken breeders with arthritis clinical signs, and an arthritis model of chicks was successfully established using SP206-2. Whole genome sequencing of the SP206-2 strain showed that the genome was 4,730,579 bp, 52.16% GC content, and contained 5007 genes, including 4729 protein-coding regions. The genomic analysis of four arthritis-causing isolates and three diarrhea-causing isolates showed that the genome of arthritis-causing isolates was subject to nonsynonymous mutations, shift mutations, and gene copy deletions. An SNP phylogenetic tree analysis showed that arthritis-causing isolates are located in a different evolutionary branch from diarrhea-causing isolates. Further differential genes analysis showed that the genome of arthritis-causing isolates had missense mutations in genes related to substance metabolism and substance transport, as a result of adaptive evolution.