Low pathogenicity avian influenza in Italy during 2007 and 2008: epidemiology and control

Since 1999, the Italian poultry production system has experienced several outbreaks of avian influenza (AI), mainly located in northeastern Italy. This paper describes the low pathogenicity (LP) AI outbreaks detected during the surveillance activities implemented in 2007-08. From May to October 2007, ten rural and hobby poultry farms were infected by an LPAI virus of the H7N3 subtype. In August-October 2007, the H7N3 LPAI virus was introduced into the industrial poultry sector with the involvement of six meat turkey farms. Phylogenetic analysis of the hemagglutinin gene indicated that all but one of the H7N3 virus strains had a high level of homology (98.7%-99.8%). Furthermore, in August 2007, an LPAI H5N2 virus was identified in a free-range geese and duck breeder flock. The hemagglutinin and neuraminidase genes showed a high level of homology (99.8% and 99.9%, respectively) with H5N2 LPAI viruses isolated from mallards in July 2007 in the same area, suggesting a possible introduction from the wild reservoir. All the birds (in total 129,386) on the infected poultry farms were culled. The prompt implementation of AI control measures, including the enforcement of a targeted emergency vaccination plan, allowed the rapid eradication of infection. In 2008, three LPAI viruses (two H7N1 and one H5N1) were identified in dealer/rural farms. The surveillance activity implemented in this area allowed the prompt detection of LPAI viruses of the H5 and H7 subtypes in the rural sector, which, as observed in the 2007 epidemic, might be the source of infection for industrial poultry.