Active surveillance for avian influenza viruses in wild birds and backyard flocks in Northern Italy during 2004 to 2006

Abstract

Following the avian influenza epidemics that occurred in Italy between 1997 and 2003, the Italian Ministry of Health in collaboration with veterinary authorities promoted, funded and implemented a national surveillance programme. The main objectives of the surveillance effort were to identify avian influenza viruses circulating in wild birds and to investigate the role of backyard poultry flocks in the dynamics of infection in a densely populated poultry area. Over 2 years (2004 to 2006), 164 backyard flocks and 4083 wild birds (mainly migratory Anseriformes and Charadriiformes) were sampled in three regions in the North of Italy. Samples collected were screened by means of real-time reverse transcriptase-polymerase chain reaction and the positive samples were processed for attempted virus isolation in embryonated fowl's specific pathogen free eggs. At the end of the study period, 27 low-pathogenic avian influenza viruses had been isolated from backyard flocks and 49 strains obtained from wild birds. Of these, 26 belonged to the H5 or H7 subtype and were closely related to contemporary low-pathogenic strains of Eurasian lineage. The findings confirm that backyard free-range farming is at high risk for avian influenza virus introduction, and confirm the role of wild waterfowl in the introduction and perpetuation of low-pathogenic avian influenza viruses during the winter season in Southern Europe.

Risk factors of primary introduction of highly pathogenic and low pathogenic avian influenza virus into European poultry holdings, considering at least material contaminated by wild birds and contact with wild birds

“…In addition to the phylogenetic data, presence of wild birds in the proximity of the effected holdings was also reported as further evidence for some of the analysed outbreaks (Bouwstra et al, 2015b;Gall-Recule et al, 2008;Therkildsen et al, 2011). Other sources of evidence presented to support the incrimination of contact with wild birds as the source of introduction were: proximity (epidemiological evidence) (Cecchinato et al, 2010;Cherbonnel et al, 2007;Conraths et al, 2016;Iglesias et al, 2010;Manvell et al, 2008;Marche et al, 2014;Probst et al, 2012;Ward et al, 2008a;Ward et al, 2009b) or phylogenetic inference, where virus was only isolated from the affected poultry holdings and compared with sequences reported in databases such as GenBank (Alexander et al, 2010;Bragstad et al, 2007;Bragstad et al, 2005;Corrand et al, 2012;Handberg et al, 2010;Hanna et al, 2015;Marche et al, 2014;Marinova-Petkova et al, 2016;Parker et al, 2014;Reid et al, 2011;Starick et al, 2008;Szeleczky et al, 2009;Terregino et al, 2007) (Table 5). …”

“…This attribution was done following epidemiological investigations that excluded the presence of undetected infected poultry holdings as the source of the detected outbreak. For 14 of the reported outbreaks, the virus serotype causing the outbreak was isolated from both the affected poultry and wild birds present in the same region around the same time, with the virus isolates showing high genetic homology (Bouwstra et al, 2015b;Gall-Recule et al, 2008;Handberg et al, 2010;Lindh et al, 2014;Terregino et al, 2007;Therkildsen et al, 2011). In addition to the phylogenetic data, presence of wild birds in the proximity of the effected holdings was also reported as further evidence for some of the analysed outbreaks (Bouwstra et al, 2015b;Gall-Recule et al, 2008;Therkildsen et al, 2011).…”

Patho-Morphological And Clinical Examinations In Experimental Infection Of Guinea Fowl (Numida Meleagris) With Lpaiv H6n2

“…In Italy, an emerging infection with HPAIV H7N7 has affected 7 bird species -chickens, turkeys, emus, goose, ducks, pelicans and guinea fowl (5). The most recent data justify the performance of a monitoring survey for the presence of AIV in birds reared in domestic conditions, including guinea fowl (6), and from some of them, a H9N2 strain was isolated.…”

Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) related with the vaccination against avian influenza of H5 and H7 subtypes in domestic poultry and captive birds

“…Both these occurrences show that, although it was not possible to avoid the introduction of AI viruses in vaccinated turkey flocks (vaccinated layers have never been involved), the spread of the infection was limited and the containment of the outbreaks was successful in a shorter time compared to previous epidemics, with a marked reduction in economic losses Since LPAI H5N2 was eradicated there have been no additional introductions of AI in the vaccinated poultry population of the DPPA in northern Italy. Thus, no virus of the H5 or H7 subtype was introduced into the vaccinated population between April 2005 and October 2006, notwithstanding 10 viral isolations of LPAI H5/H7 strains in wild birds (Terregino et al, 2007), and the 16 swans and one mallard found positive to the Asian HPAI H5N1 virus .…”