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

The novel Eurasian lineage clade highly pathogenic avian influenza (HPAI) A(H5N8) virus (http:// spread rapidly and globally during 2014, substantially affecting poultry populations. The first outbreaks were reported during January 2014 in chickens and domestic ducks in South Korea and subsequently in China and Japan (1-4), reaching Germany, the Netherlands, and the United Kingdom by November 2014 and Italy in early December 2014 (5). Also in November 2014, a novel HPAI H5N2 virus was reported in outbreaks on chicken and turkey farms in Fraser Valley, British Columbia, Canada (5). This H5N2 influenza virus is a reassortant that contains the Eurasian clade H5 plus 4 other Eurasian genes (polymerase acidic protein subunit, matrix protein, polymerase basic protein subunit [PB] 2, nonstructural protein) and 3 North American wild bird lineage genes (neuraminidase [NA], nucleoprotein, PB1) (5). Taiwan has recently reported novel reassortants of the H5 clade with other Eurasian viruses (H5N2, H5N3).

The appearance of highly similar Eurasian H5N8 viruses in Asia, Europe, and now the United States suggests that this novel reassortant may be well adapted to certain waterfowl species, enabling it to survive long migrations (6). These appearances also represent a major change in Eurasian H5 virus circulation. After the reported spread of HPAI H5N1 virus in Asia, a large, interagency avian influenza virus (AIV) surveillance effort was implemented throughout the United States during April 2006-March 2011 (7). Of nearly 500,000 wild bird samples tested, none harbored Eurasian subtype H5 AIV. The overall prevalence of AIV was [approximately equal to] 11%, and most viruses (86%) were detected in dabbling ducks (family Anatidae) (8). Although H5N8 subtype viruses have been detected previously in the United States, all have been low pathogenicity AIV of North American wild bird lineage.

Case Reports

After the November 2014 report of H5N2 HPAI outbreaks among poultry in British Columbia, the US Departments of Agriculture and Interior, together with state agency personnel, increased surveillance of poultry flocks, hunter-harvested wild birds, and wild bird die-offs along the US-Canada border. A wild bird die-off was reported on December 1, 2014, at Wiser Lake (48.9039N, 122.4799W) in Whatcom County, Washington, USA. The lake, which has a history of waterfowl deaths caused by lead poisoning and aspergillosis, is located [approximately equal to] 32 km from the location of the index cases in Fraser Valley. Up to 10,000 waterfowl were on the lake when the deaths began. The dead birds consisted primarily of mallards (Anas platyrhynchos), American wigeon (A. americana), and northern pintail (A. acuta), along with smaller numbers of other waterfowl species.

Nine carcasses were submitted to the National Wildlife Health Center (Table 1); 6 were examined in detail. Aspergillus fumigatus was isolated from 5 birds with characteristic lesions of airsacculitis (Table 1). In addition, cloacal and/or oral swab samples from 5 birds had molecular assay results positive for influenza A and H5 (Table 1). A Eurasian lineage H5 clade AIV, A/northern pintail/Washington/40964/2014 (H5N2) (GenBank taxon no. 1589662), was isolated from a lung specimen. Wholegenome sequencing indicated the virus was highly similar to the H5N2 reassortant virus from Canada. Both viruses have 3 RNA segments of North American wild bird lineage (PB1, nucleoprotein, and NA) and 5 RNA segments (PB2, polymerase acidic, HA, matrix protein, and nonstructural protein) that showed >99% similarity to 2014 Eurasian clade H5N8 viruses (Table 2). According to World Organisation for Animal Health guidelines (9), the virus was consistent with HPAI on the basis of the amino acid sequence at the hemagglutinin cleavage site and in vivo assay results (intravenous pathogenicity index 2.57).

In a related event, on December 6, 2014, an American wigeon was captured and partially consumed by a captive-reared gyrfalcon (Falco rusticolus) in Whatcom County, [approximately equal to] 8 km from Wiser Lake. The wigeon remains were also fed to 3 other gyrfalcon and gyrfalcon-peregrine hybrids at a farm with another 25 raptors and 40 pigeons. The first falcon (RW099878) died on December 8 and was submitted to the National Wildlife Health Center. The second falcon (RX085847) also died on December 8 and the third (RX093091) on December 11; the fourth (RX084955) was euthanized on December 11. Carcasses of these last 3 falcons were submitted to the Washington Animal Disease Diagnostic Laboratory. No further deaths or illnesses have been reported among other raptors at the facility. Histologic and pathologic findings for the 3 raptors were consistent with those described in previous reports of H5N8 infections (1,6), and the severity of the lesions corresponded to virus concentrations detected in the tissues by molecular assays; results will be further detailed in a subsequent publication.

Molecular assay results for oral and cloacal swab samples and major organ and brain samples from falcon RW099878 were positive for influenza A and H5 viruses. For falcons RW099878 and RX085847, partial HA and NA genes were directly sequenced from brain and oral swab samples. A Eurasian lineage H5 clade AIV, A/gyrfalcon/Washington/41088-6/2014 (H5N8) (GenBank taxon no. 1589663), was isolated from the brain of falcon RW099878. All 8 RNA segments for the strain were >99% similar to those for 2014 Group A H5N8 strains from South Korea (3) (Table 2); the amino acid sequence at the hemagglutinin cleavage site and in vivo assay results (intravenous pathogenicity index 2.65) were consistent with HPAI.

Phylogenetic analysis of the H5 clade viruses detected in the United States resulted in 3 major findings (Figures 1, 2; online Technical Appendix, http://wwwnc. First, the Eurasian lineage avian H5N8 clade virus survived introduction into North America in its entirety. Second, introduction of Eurasian H5N8 virus into North America appears to be independent from introductions of the virus into Europe. Third, the duration of circulation of H5N8 virus in the Pacific flyway (California, Idaho, Nevada, Oregon, Utah, and Washington, USA) is unknown, but it was sufficient for reassortment with low pathogenicity North American lineage wild bird AIV (Figure 1).


The ongoing circulation of these Eurasian HPAI H5 viruses in wild birds considerably alters the potential risks and subsequent consequences for US poultry and wildlife rehabilitation centers. Detection of HPAI H5N8 virus in apparently healthy common teal (A. crecca), Eurasian wigeon (A. penelope), mallard, spot-billed duck (A. poecilorhyncha), and tundra swans (C. columbianus) (3,5) suggests that wild birds may contribute to further spread of this HPAI H5 lineage in North America. However, culling and otherwise disturbing wild birds or their habitats has not been shown to be beneficial in the control of avian influenza (11). The scientifically supported management action (11) is to enhance biosecurity to minimize contacts between poultry, wild birds, and their fomites (11). In addition, hunters should be cognizant of risks from handling potentially infected carcasses ( birdbiosecurity/downloads/USDA_HntrCd_Hi.pdf).

Examination of wild bird surveillance samples collected before December 2014 may provide further insight into the timing and route of introduction of the Eurasian clade H5N8 virus into North America. In addition, enhanced and ongoing influenza surveillance in wild birds and poultry will contribute to a better understanding of the geographic distribution and species involved in the spread of these HPAI H5 viruses. Together, these data may enable waterfowl managers and poultry producers to better assess and manage disease risks. Human infections have not been associated with either virus; however, H5 clade 2.3.4 H5N1 virus has caused human death, so caution is warranted. During preparation of this article, H5N8 was reported in wild birds and poultry along the Pacific flyway; novel H5N2 virus was detected in Idaho, Oregon, and Washington; and another novel reassortant H5N1 was detected in Washington and British Columbia (5). These detections have had major effects on US poultry trade (12).


We acknowledge the dedicated staff at our respective institutions, who ensured timely field support, rapid response, and prompt and accurate laboratory testing; in particular, Renee Long, Katy Griffin, Jeffery Messer, Karin McMullen, Amber Itle, and Thomas Gilliom.

Dr. Ip is the section head of the Diagnostic Virology Laboratory, Wildlife Disease Diagnostic Laboratories Branch, US Geologic Survey-National Wildlife Health Center. His research interests include emerging diseases of wildlife, disease transmission and persistence in natural populations, and laboratory diagnostics development.


(1.) Kim Y-L, Pascua PNQ, Kwon H-I, Lim G-J, Kim E-H, Yoon S-W, et al. Pathobiological features of a novel, highly pathogenic avian influenza A(H5N8) virus. Emerging Microbes and Infections. 2014;3:e75.

(2.) Lee YJ, Kang HM, Lee EK, Song BM, Jeong J, Kwon YK, et al. Novel reassortant influenza A(H5N8) viruses, South Korea, 2014. Emerg Infect Dis. 2014;20:1087-9. eid2006.140233

(3.) Jeong J, Kang HM, Lee EK, Song BM, KwonYK, Kim HR, et al. Highly pathogenic avian influenza virus (H5N8) in domestic poultry and its relationship with migratory birds in South Korea during 2014. Vet Microbiol. 2014;173:249-57. http://dx.doi. org/10.1016/j.vetmic.2014.08.002

(4.) Zhao K, Gu M, Zhong L, Duan Z, Zhang Y, Zhu Y, et al. Characterization of 3 H5N5 and one H5N8 highly pathogenic avian influenza viruses in China. Vet Microbiol. 2013;163:351-7.

(5.) World Organisation for Animal Health. Summary of immediate notifications and follow-ups-2014. Highly pathogenic avian influenza [cited 2014 Dec 14]. wahid.php/Diseaseinformation/Immsummary

(6.) Kang H-M, Lee E-K, Song B-M, Jeong J, Choi J-G, Jeong J, et al. Novel reassortant influenza A(H5N8) viruses among domestic and wild ducks, South Korea, 2014. Emerg Infect Dis. 2015;21:298304.

(7.) Olsen B, Munster VJ, Wallensten A, Waldenstrom J, Osterhaus AD, Fouchier RA. Global patterns of influenza a virus in wild birds. Science. 2006;312:384-8. science.1122438

(8.) Bevins SN, Pedersen K, Lutman MW, Baroch JA, Schmit BS, Kohler D, et al. Large-scale avian influenza surveillance in wild birds throughout the United States. PLoS ONE. 2014;9:e104360.

(9.) World Organisation for Animal Health (OIE). Avian influenza. Chapter 2.3.4. In: Manual of diagnostic tests and vaccines for terrestrial animals. Paris: The Organisation; 2014.

(10.) Tamura K, Peterson D, Peterson N, Stecher G, Nei M, Kumar S. MEGA5: Molecular Evolutionary Genetics Analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods. Mol Biol Evol. 2011;28:2731-9. http://dx.doi. org/10.1093/molbev/msr121

(11.) The Scientific Task Force on Avian Influenza and Wild Birds. Statement on H5N8 highly pathogenic avian influenza (HPAI) in poultry and wild birds [cited 2014 Dec 14]. news/statement-on-h5n8-highly-pathogenic-avian-influenza-hpaiin-poultry-and-wild-birds

(12.) United States Department of Agriculture, Food Safety Inspection Service. Recently revised export requirements [cited 2015 Jan 13]. international-affairs/exporting-products/export-libraryrequirements-by-country

Address for correspondence: Mia Kim Torchetti, USDA APHIS VS National Services Veterinary Laboratories, 1920 Dayton Ave, Ames, IA 50010, USA; email:

Hon S. Ip, [1] Mia Kim Torchetti, [1] Rocio Crespo, Paul Kohrs, Paul DeBruyn, Kristin G. Mansfield, Timothy Baszler, Lyndon Badcoe, Barbara Bodenstein, Valerie Shearn-Bochsler, Mary Lea Killian, Janice C. Pedersen, Nichole Hines, Thomas Gidlewski, Thomas DeLiberto, Jonathan M. Sleeman

Author affiliations: US Geologic Survey-National Wildlife Health Center, Madison, Wisconsin, USA (H.S. Ip, B. Bodenstein, V. Shearn-Bochsler, J.M. Sleeman); US Department of Agriculture, Ames, Iowa, USA (M.K. Torchetti, M.L. Killian, J.C. Pedersen, N. Hines); Washington State University, Pullman, Washington, USA (R. Crespo, T. Baszler); Washington Department of Agriculture, Olympia, Washington, USA (P. Kohrs, T. Baszler, L. Badcoe); Washington Department of Fish and Wildlife, Olympia (P. DeBruyn, K.G. Mansfield); US Department of Agriculture, Fort Collins, Colorado, USA (T. Gidlewski, T. DeLiberto)


[1] These first authors contributed equally to this article.

Table 1. Summary of influenza test results for samples from 10 birds
from Washington, USA, 2014 *

Sample ID no.    Species, common name   Necropsy

26080-001         Northern shoveler        Yes
26080-002          Northern pintail        Yes
26080-003          American wigeon         Yes
26080-004          American wigeon         No
26080-005          American wigeon         No
26080-006              Mallard             Yes
26080-007              Mallard             Yes
26080-008              Mallard             No
26080-009           Trumpeter swan         Yes
RW099878              Gyrfalcon            Yes

Sample ID no.               AIV status              Diagnostic finding

26080-001        PCR negative, isolation negative      Aspergillosis
26080-002                  Subtype H5N2             Aspergillosis, HPAI
26080-003        PCR positive, isolation negative      Aspergillosis
26080-004        PCR negative, isolation negative           ND
26080-005        PCR negative, isolation negative           ND
26080-006        PCR positive, isolation negative      Aspergillosis
26080-007        PCR positive, isolation negative      Aspergillosis
26080-008        PCR positive, isolation negative           ND
26080-009        PCR negative, isolation negative       Emaciation
RW099878                   Subtype H5N8                    HPAI

* AIV, avian influenza virus; HPAI, highly pathogenic avian influenza;
ID, identification, ND, not determined.

([dagger]) Specimens tested by the Washington Animal Disease
Diagnostic Laboratory.

Table 2. Nucleotide identity between the influenza A(H5N2) and A(H5N8)
viruses from Washington, USA, and their nearest homologues in GenBank
as of January 8, 2015 *

Virus from                     Nearest homologue            % Identity
Washington State

A/Northern pintail/
2014 (H5N2)
  PB2                     A/bean goose/Korea/H40/2014          99.5
  PB1                  A/bufflehead/California/3118/2011       99.0
  PA                    A/common teal/Korea/H455-30/2014       99.5
  HA                       A/crane/Kagoshima/KU1/2014          99.3
  NP                        A/American green-winged            99.1
  NA                   A/bufflehead/California/4935/2012       99.0
  MP                     A/Baikal teal/Korea/S005/2014        100.0
  NS                   A/Baikal teal/Korea/Donglim3/2014       99.9
2014 (H5N8)
  PB2                     A/bean goose/Korea/H40/2014          99.6
  PB1                     A/Baikal teal/Korea/H41/2014         99.4
  PA                   A/Baikal teal/Korea/Donglim3/2014       99.3
  HA                       A/crane/Kagoshima/KU1/2014          99.2
  NP                      A/Baikal teal/Korea/H41/2014         99.5
  NA                         A/Coot/Korea/H81/2014             99.4
  MP                   A/Baikal teal/Korea/Donglim3/2014       99.9
  NS                   A/Baikal teal/Korea/Donglim3/2014      100.0

* HA, hemagglutinin; MP, matrix protein; NA, neuraminidase; NP,
nucleoprotein; NS, nonstructural, PA, polymerase acidic; PB1 and 2,
polymerase basic 1 and 2.
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Article Details
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Title Annotation:DISPATCHES
Author:Ip, Hon S.; Torchetti, Mia Kim; Crespo, Rocio; Kohrs, Paul; DeBruyn, Paul; Mansfield, Kristin G.; Ba
Publication:Emerging Infectious Diseases
Geographic Code:9SOUT
Date:May 1, 2015
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