01.01.2017

EID, Vol. 23, No. 2 - February 2017

Highly pathogenic avian influenza virus (HPAIV) subtype H5N1 was first isolated from a goose in 1996 in Guangdong China (Gs/GD). This virus evolved into multiple hemagglutinin (HA) genetic clades and underwent reassortment with different neuraminidase and internal genes to generate subtype H5N8 clade 2.3.4.4 Gs/GD HPAIV, which first appeared in an outbreak in poultry in China in 2013, followed closely by outbreaks in South Korea in January 2014. During these outbreaks, 2 distinct groups of H5N8 viruses were identified; group A (Buan-like) and group B (Gochang-like). There have been no further reports of group B virus since its original detection in China and South Korea during 2014. In contrast, in early 2014, group A viruses predominated in South Korea. On the basis of aquatic bird migration patterns, it is hypothesized that HPAIV (H5N8) reached Siberia during the 2014 spring bird migration. The virus was probably carried by birds from Siberia to various countries of Asia, Europe, and North America during the fall migration, representing an intercontinental group A (icA). 
In June 2016, samples were collected from dead wild aquatic birds around Uvs-Nuur Lake (Tyva Republic) at the Russia–Mongolia border. These isolates were further characterized as H5N8 clade 2.3.4.4 group B HPAIV.
Uvs-Nuur Lake is a key habitat for 46 resident waterfowl species and 215 kinds of birds migrating south from Siberia, suggesting this area is a useful site for surveillance of HPAIV in wild aquatic birds. Because numerous species of migratory shorebirds and waterfowl use the summer breeding grounds of Siberia, the identification of HPAIV infection in wild aquatic birds in this area signifies the potential for wide dissemination of these novel reassortant Group B H5N8 viruses during the 2016 fall migration.