Long-term monitoring for avian influenza viruses in wild bird species in Italy

摘要

The first reported isolation of an influenza virus from wild birds was obtained in 1961 from common terns (Sterna hirundo) in South Africa, where a highly pathogenic avian influenza (HPAI) virus (H5N3 subtype) caused the death of about 1300 birds (Stallknecht and Shane, 1988). Although evidence for the infection of wild birds with influenza viruses existed prior to the 1970s, it was not until then that systematic surveillance studies revealed the widespread distribution of influenza viruses in wild avian populations (Webster et al., 1992). To date a vast number of low pathogenicity avian influenza (LPAI) viruses have been isolated from a wide variety of birds. The HPAI viruses have rarely been isolated from feral birds, and when they have it has usually been from wild birds found dead in the vicinity of farms infected by HPAI viruses (Capua et al., 2000). The above-mentioned mass mortality among common terns represents the only case reported to date of influenza infection in free-living birds that is associated with obvious signs of disease and is unrelated to outbreaks of HPAI viruses in domestic birds (Alexander, 2000).