Outbreak-associated novel avipoxvirus in domestic mallard ducks, China.

To the Editor: In December 2013, an unidentified disease in domestic mallard ducks (Anas platyrhynchos) occurred in Guangxi Province, China. Rates of illness in adult male and female ducks were 50%–70% and 5%–30%, respectively, in different flocks. No deaths were observed. Clinical signs included cutaneous nodules on the birds’ eyelids, beaks, and legs. All classical endemic viruses and bacteria, including avian influenza virus, avian paramyxovirus 1, duck enteritis virus, Riemerella anatipestifer, and Escherichia coli, were excluded as causative agents by PCR or bacteria isolation. During investigation of the illness, we isolated a novel duck-pathogenic avipoxvirus (APV) from skin nodules of the affected ducks.