Active surveillance for Avian Influenza viruses in wild birds and backyard flocks in Northern Italy during 2004-2006
Résumé
Following the avian influenza (AI) 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 (AIVs) circulating in wild birds and to investigate the role of backyard poultry flocks in the dynamics of infection in a densely populated poultry area (DPPA). Over two years (2004-2006) 164 backyard flocks and 4,083 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 (RRT-PCR) and the positive samples were processed for attempted virus isolation in embryonated fowl's specific pathogen free (SPF) eggs. At the end of the study period 27 low pathogenic avian influenza (LPAI) 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 AIVs introduction, and the role of wild waterfowl in the introduction and perpetuation of LPAI viruses during the winter season in Southern Europe.
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