Highly pathogenic avian influenza (H7N1) in ostriches (Struthio camelus)

The clinical, virological and pathological findings observed in a natural outbreak of highly pathogenic avian influenza in intensively farmed ostriches (Struthio camelus) are reported. Clinical signs characterized by anorexia, depression, nervous and enteric signs were observed in young birds, which resulted in death of 30% of the affected birds. Virus isolation performed in accordance with the guidelines listed in European Union Directive 92/40/EEC yielded an influenza A virus of the H7N1 subtype with a deduced cleavage site motif containing multiple basic amino acids, typical of highly pathogenic viruses. Gross lesions, mainly haemorrhagic enteritis and liver degeneration and necrosis, were confirmed by histopathology and immunohistochemistry, resulting in the detection of necrotic lesions and influenza A nucleoprotein in selected organs. The findings reported indicate that ostriches are susceptible to highly pathogenic avian influenza.