Identification of avihepadnaviruses and circoviruses in an unexplained death event in farmed ducks.

Research into disease pathogens can greatly benefit from viral metagenomics technology. Using this technique, we investigated potential disease pathogens that resulted in the death of many ducks on a duck farm. Two duck circoviruses (DuCV) and one duck hepatitis B virus (DHBV) were detected and identified, and all three strains were closely related to avian-associated viruses. Two duck circoviruses had 81.64%-97.65% genome-wide sequence identity to some reference strains, and duck hepatitis B virus shared 75.85%-98.92% identity with other strains. Clinical characteristics of the diseased ducks, including ruffled feathers, lethargy, and weight loss, were comparable to those observed in cases of DuCV infection. Further research is needed to determine whether coinfection with DHBV leads to liver damage and exacerbation of the disease.