First introduction of highly pathogenic H5N1 avian influenza A viruses in wild and domestic birds in Denmark, Northern Europe

Abstract

The first case of HP H5N1 infection of wild and domestic birds in Denmark was experienced in March 2006. This is the first full genome characterisation of HP H5N1 avian influenza A virus in the Nordic countries. The Danish viruses from this time period have their origin from the wild bird strains from Qinghai in 2005. These viruses may have been introduced to the Northern Europe through unusual migration due to the cold weather in Eastern Europe at that time.

Avian Influenza Virus (H5N1) Replication in Feathers of Domestic Waterfowl

“…A/chicken/Miyazaki/K11/2007 (Ck/ Miya/K11/07) belongs to genotype Z and H5 clade 2 subclade 2 (M. Mase, unpub. data), which is now circulating from China to Japan, Europe, and Africa (5,14). The stored virus was propagated for 36-48 hours in the allantoic cavity of 10-day-old embryonated chicken eggs at 37°C.…”

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). …”

Avian Influenza Virus (H5N1) Mortality Surveillance

“…Initial spread from Southeast Asia before 2005 was likely the result of transport of infected poultry because the spread was not easily explained by natural bird movements (4,5). However, its spread to Western Europe in late 2005 could be explained by weatherinduced migration of waterfowl after a freeze in Eastern Europe (6,7). Since spreading to Sweden and Denmark in early 2006, the virus has been detected there in dead birds of numerous species (Table).…”

“…Certainly, both pathogens are presumed to be vectored in association with human activities (7,8), but B. dendrobatidis exhibits a greater host and geographic range and thus should exhibit greater prevalence if humans were mediating introduction across the range of our study. Second, human activities such as construction and industry, may directly or indirectly infl uence the basic reproductive number, R 0 , of ranavirus to a greater extent than for that of B. dendrobatidis.…”