Novel Eurasian highly pathogenic avian influenza A H5 viruses in wild birds, Washington, USA, 2014

Abstract

Novel Eurasian lineage avian influenza A(H5N8) virus has spread rapidly and globally since January 2014. In December 2014, H5N8 and reassortant H5N2 viruses were detected in wild birds in Washington, USA, and subsequently in backyard birds. When they infect commercial poultry, these highly pathogenic viruses pose substantial trade issues.

Keywords: A(H5N2); A(H5N8); H5N2; H5N8; HPAI; United States; highly pathogenic avian influenza virus; influenza; intercontinental transmission; reassortment; viruses; wild birds.

Figure 1

Phylogenetic comparison of the complete hemagglutinin genes of highly pathogenic avian influenza A(H5N2) and A(H5N8) strains from the United States with strains from Asia, Europe, and Canada. Solid circles indicate H5N2 and H5N8 strains from the United States; open circle indicates H5N2 strain from Canada; black triangle indicates H5N8 strain from a crane in Japan. Sequences were aligned by using MUSCLE, and phylogenetic and molecular evolutionary analyses were conducted by using MEGA version 5, using the neighbor-joining tree-building method, with 1,000 bootstrap replicates (10). Scale bar indicates nucleotide substitutions per site. Analysis was done with viruses that were phylogenetically representative of appropriate lineages (Influenza Virus Resource Database, http://www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html).

Figure 2

Phylogenetic comparison of the complete neuraminidase genes of highly pathogenic avian influenza A(H5N2) (panel A) and A(H5N8) (panel B) strains from the United States with strains from Asia, Europe, and Canada. Solid circles indicate H5N2 and H5N8 strains from the United States; black triangle indicates H5N8 strain from a crane in Japan. Sequences were aligned by using MUSCLE, and phylogenetic and molecular evolutionary analyses were conducted by using MEGA version 5, using the neighbor-joining tree-building method, with 1,000 bootstrap replicates (10). Scale bar indicates nucleotide substitutions per site. Analysis was done with viruses that were phylogenetically representative of appropriate lineages (Influenza Virus Resource Database, http://www.ncbi.nlm.nih.gov/genomes/FLU/FLU.html).