Foot-and-mouth disease (FMD) is classified as a Class I animal disease in China and listed as one of the notifiable animal diseases by the World Organization for Animal Health (WOAH). It significantly impacts the safe production of livestock and the trade of animals and related products. China’s Yunnan Province shares a 710 km border with Laos, with frequent cross-border trade, and the cross-border flow of animals and related products occurs from time to time. In order to prevent the introduction of FMD from the border areas of Laos into China, this study conducted an assessment of the entry, exposure, and consequences of FMD transmission. The findings revealed a “high” risk in terms of entry assessment, a “medium” risk in exposure assessment, and a “high” risk in the consequence assessment. Based on these assessments, the overall risk level for the introduction of FMD from Laos into China is determined to be “high”. Therefore, it is recommended that management measures are implemented, such as restricting animal movement across borders and strengthening inspection procedures for animals entering China, to effectively prevent FMD introduction from Laos.

Duck viral hepatitis, caused by Duck Hepatitis A Virus Type 3 (DHAV-3), remains a major threat to young ducklings. Although DHAV-3 has circulated in China since the 1999s, the complete genomic architecture, exact virulence parameters, and evolutionary distance between early Yunnan isolates and current field strains have remained undefined. This study investigated six DHAV-3 strains isolated in Yunnan Province, China, between 2004 and 2006, to elucidate their genetic and biological characteristics. Full-genome sequencing and phylogenetic analysis revealed >99.5% nucleotide and >99.6% amino acid identity among the strains, suggesting a common ancestral origin. In vivo challenge assays showed rapid onset of clinical signs and >90% mortality in ducklings within 36 h post-inoculation. Embryonic deaths began at 24 h post-infection and peaked by 90 h. Viral replication was efficient in DEF, DEK, Vero, and BHK-21 cells, but absent in chicken fibroblasts (DF-1). Comparative genomic analysis between the YN/LR/2005 strain and recent field isolates (2022–2024) revealed substantial nucleotide divergence in structural regions, with 32 unique amino acid substitutions—all five located in the immunodominant VP1 region that may influence viral antigenicity and host interaction—alongside changes in N-glycosylation sites and alterations in protein secondary structure. Histopathological examination confirmed characteristic hepatic lesions. These findings demonstrate that while DHAV-3 has undergone genetic evolution, it retains high virulence, underscoring the need for ongoing molecular surveillance and supporting future vaccine and diagnostic development.