Figure 3. Mean cloacal excretion of highly pathogenic avian influenza virus (H5N1) by wild ducks by A) virus isolation and C) reverse transcription–PCR (RT-PCR). Legend for panels A–D as in Figure 2. E) Pancreas showing multiple foci of necrosis (between arrowheads) in a pochard. F) Pancreatic acinar cells in a pochard and H) hepatocytes in a tufted duck, showing the transition area between normal and necrotic tissue expressing abundant influenza virus antigen. G) Pancreatic lesions in a pochard and I) hepatic lesions in a tufted duck, characterized by sharp transition between normal tissue (left side of panels) and foci of necrosis and inflammatory cell infiltration (right side of panels). F, G original magnification ×50. H, I original magnification ×100. Tissues were stained either by immunohistochemistry that used a monoclonal antibody against the nucleoprotein of influenza A virus as a primary antibody (F, H) or with hematoxylin and eosin (G, I).