OIE: Highly pathogenic avian influenza ,United States of America

Information received on 20/01/2015 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	Immediate notification
Date of start of the event	29/12/2014
Date of pre-confirmation of the event	16/01/2015
Report date	20/01/2015
Date submitted to OIE	20/01/2015
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

New outbreaks

Summary of outbreaks

Total outbreaks: 1

Outbreak Location

WASHINGTON ( Whatcom County, Whatcom )

Total animals affected

Species	Susceptible	Cases	Deaths	Destroyed	Slaughtered
Green-winged Teal:Anatidae (Anas carolinensis)		**

Outbreak statistics

Species	Apparent morbidity rate	Apparent mortality rate	Apparent case fatality rate	Proportion susceptible animals lost*
Green-winged Teal:Anatidae (Anas carolinensis)	**	**	**	**

* 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 has been 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.
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

National Veterinary Services Laboratories (NVSL) ( National laboratory )

Tests and results