Low pathogenic avian influenza in domestic fowl in Norfolk, England, March and April, 2006

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). …”

“…Other sources of introduction into commercial poultry holdings were the presence of undetected circulation in backyard flocks and scavenging (DEFRA, 2006;Manvell et al, 2008). The former resulted in trade of infected live animals within rural (mixed outdoor) holdings or sharing of personnel or contaminated equipment between holdings under the same ownership ( The present document has been produced and adopted by the bodies identified above as authors.…”

“…These holdings are expected the have the highest level of biosecurity and still virus introduction took place. The route of introduction of the virus into the poultry houses was considered to take place via footwear or equipment contaminated with wild bird faeces (Conraths et al, 2016;Manvell et al, 2008). This route of entry, contaminated fomites, could also explain the routes of entry into the affected indoor holdings analysed in this review ( Figure 1).…”

“…It is noteworthy considering the outbreaks that took place in chicken breeder holdings (n = 3) (Manvell et al, 2008;Parker et al, 2012;Probst et al, 2012). These holdings are expected the have the highest level of biosecurity and still virus introduction took place.…”

“…In case of the latter, it was speculated that scavenging foxes brought infected carcasses to the premises of a broiler breeder holding, contaminating the environment and virus was later introduced into the poultry house via contaminated footwear worn by staff or egg collection teams (biosecurity flaw) (DEFRA, 2006;Manvell et al, 2008).…”