Spillover of Riemerella anatipestifer to laying hens leads to a decrease in egg production and hatchability

A strain of Riemerella anatipestifer,a bacterium that primarily infects ducks and geese, was isolated from a layer. Genetic analysis of the housekeeping genes (16S rRNA and rpoB), key virulence genes (prtC, hagA, and sspA), and dominant antigen gene (ompA) revealed that this isolate is closely related to strains commonly found in eastern China. Animal studies successfully replicated clinically similar cases, characterized by decreased egg production and reduced hatching rates, with the primary findings observed in the oviducts. Epidemiological investigations indicated that the disease has emerged in chicken farms across at least 5 provinces. Given these findings, enhanced surveillance is urgently needed to assess the potential impact on the poultry industry, particularly the layer sector, and to implement necessary measures to control the spread of the disease.