USA - 1 new outbreak of highly pathogenic avian influenza virus H5N1 in American wigeon, Whatcom, Washington (OIE, April 15, 2015)

[Pathfinder]

Highly pathogenic avian influenza, United States of America

Information received on 15/04/2015 from Dr John Clifford, Deputy Administrator, Animal and Plant Health Inspection Service, United States Department of Agriculture, Washington, United States of America

Summary Report type Follow-up report No. 7 Date of start of the event 16/01/2015 Date of confirmation of the event 16/01/2015 Report date 15/04/2015 Date submitted to OIE 15/04/2015 Reason for notification Reoccurrence of a listed disease Date of previous occurrence 2004 Manifestation of disease Sub-clinical infection Causal agent Highly pathogenic avian influenza virus Serotype H5N1 Nature of diagnosis Laboratory (advanced) This event pertains to a defined zone within the country Related reports Immediate notification (20/01/2015) Follow-up report No. 1 (03/02/2015) Follow-up report No. 2 (13/02/2015) Follow-up report No. 3 (25/02/2015) Follow-up report No. 4 (05/03/2015) Follow-up report No. 5 (20/03/2015) Follow-up report No. 6 (08/04/2015) Follow-up report No. 7 (15/04/2015)

New outbreaks (1)

Outbreak 1 Whatcom County, Whatcom, WASHINGTON Date of start of the outbreak 05/03/2015 Outbreak status Continuing (or date resolved not provided) Epidemiological unit Not applicable Affected animals Species Susceptible Cases Deaths Destroyed Slaughtered American wigeon:Anas americana(Anatidae) Affected population Wild bird surveillance.

Summary of outbreaks Total outbreaks: 1 Total animals affected Species Susceptible Cases Deaths Destroyed Slaughtered American wigeon:Anas americana(Anatidae) ** Outbreak statistics Species Apparent morbidity rate Apparent mortality rate Apparent case fatality rate Proportion susceptible animals lost* American wigeon:Anas americana(Anatidae) ** ** ** ** *Removed from the susceptible population through death, destruction and/or slaughter **Not calculated because of missing information

Epidemiology Source of the outbreak(s) or origin of infection Contact with wild species Epidemiological comments As part of the increased AI surveillance of wild birds (performed by testing hunter harvested birds), another Eurasian H5 clade 2.3.4.4 virus was identified through whole genome sequencing of the virus isolate. Introduction of the Eurasian (EA) H5N8 virus into the Pacific Flyway sometime during late 2014 has allowed mixing with North American (AM) lineage viruses and generated new combinations with genes from both EA and AM origin (or “reassortant” viruses) such as the EA/AM H5N2-reassortant detected in Canada and the United States. Such findings are not unexpected as the EA-H5N8 virus continues to circulate. A novel EA/AM H5N1-reassortant clade 2.3.4.4 was isolated from an American green winged teal in Whatcom County, Washington. This H5N1 subtype is different from strain circulating in Asia. The gene constellation is as follows: Eurasian lineage genes (PB2, H5, NP, MP >99% identical to A/gyrfalcon/WA/41088/2014 H5N8); North American lineage genes (PB1 {98% identical to A/Northern pintail/Washington/40964/2014 H5N2}, PA, N1, NS of North American LPAI wild bird lineage. The HA cleavage site is compatible with strains that are highly pathogenic. As of 15 April 2015 there was one new occurrence in wild birds of novel EA/AM H5N1. This novel HPAI EA/AM H5N1-reassortant virus has NOT been found in commercial poultry anywhere in the United States.

Control measures Measures applied Vaccination prohibited No treatment of affected animals Measures to be applied No other measures

Diagnostic test results Laboratory name and type Species Test Test date Result National Veterinary Services Laboratories (NVSL) (National laboratory) American wigeon real-time reverse transcriptase/polymerase chain reaction (RRT-PCR) 05/03/2015 Positive National Veterinary Services Laboratories (NVSL) (National laboratory) American wigeon virus sequencing 05/03/2015 Positive

Future Reporting The event is continuing. Weekly follow-up reports will be submitted.

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