3.1 Clinical signs and post-mortem examinations
For both NDRV outbreaks, most diseased ducklings were characterized by diarrhea, lethargy, increased eye discharge, loss of appetite, stunted growth, and paralysis. Among the organs collected from the dead ducklings in both cases, the predominant histologic lesions are located in the liver and spleen. The livers (Figure 1a, 1b, 1c) and spleens (Figure 1d, 1e, 1f) showed swelling, hemorrhage, and irregular necrosis in all dead ducklings. And other organs did not exhibit apparent lesions.