RESEARCH Spread of Influenza Virus A (H5N1) Clade 2.3.2.1 to Bulgaria in Common Buzzards

• Main Authors: Atanaska Marinova-petkova, Georgi Georgiev, Patrick Seiler, Daniel Darnell, John Franks, Scott Krauss, Richard J. Webby, Robert G. Webster
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2010
• Subjects: Penfold; Sterna hirundo
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.307.14; http://wwwnc.cdc.gov/eid/article/18/10/pdfs/12-0357.pdf

virus was isolated from the carcass of a common buzzard (Buteo buteo) in Bulgaria. Phylogenetic analyses of the virus showed a close genetic relationship with infl uenza virus A (H5N1) clade 2.3.2.1 viruses isolated from wild birds in the Tyva Republic and Mongolia during 2009–2010. Designated A/common buzzard/Bulgaria/38WB/2010, this strain was highly pathogenic in chickens but had low pathogenicity in mice and ferrets and no molecular markers of increased pathogenicity in mammals. The establishment of clade 2.3.2.1 highly pathogenic avian infl uenza viruses of the H5N1 subtype in wild birds in Europe would increase the likelihood of health threats to humans and poultry in the region. Wild aquatic birds are considered natural reservoirs of all known influenza virus subtypes (1). Highly pathogenic avian influenza viruses (HPAIVs) usually cause asymptomatic infections in waterfowl. Compared with that for poultry, the number of reported outbreaks of HPAIVs in wild birds (aquatic or terrestrial) before 2002 was low; 1 influenza A (H5N3) outbreak occurred in wild common terns (Sterna hirundo) in South Africa in 1961 (2), and H7 subtype HPAIV was isolated from a Saker falcon (Falco cherrug) in Italy in 2000 (3). In December 2002, a die-off of aquatic waterfowl caused by an HPAIV (H5N1) occurred in Penfold Park in Hong Kong. That event was followed by