Analysis of H5N1 avian influenza infections from wild bird surveillance in Hong Kong from January 2006 to October 2007

Intensive surveillance of dead wild birds for H5N1 avian influenza infection is conducted in Hong Kong. Between January 2006 and October 2007 pooled cloacal and tracheal swabs from 17692 dead wild birds (from 16 different orders including 82 genera) were tested and 33 H5N1 highly pathogenic avian in...

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Bibliographic Details
Published in:	Avian pathology Vol. 38; no. 2; pp. 107 - 119
Main Authors:	Ellis, Trevor M, Dyrting, Kitman C, Wong, Chun W, Chadwick, Brad, Chan, Cassius, Chiang, Micah, Li, Clara, Li, Pamela, Smith, Gavin J.D, Guan, Yi, Peiris, J.S. Malik
Format:	Journal Article
Language:	English
Published:	England Taylor & Francis Group 01-04-2009 Taylor & Francis Ltd
Subjects:	Animal diseases Animals Animals, Domestic - virology Animals, Wild - virology Aves Avian flu avian influenza bird diseases Birds - classification Birds - virology Cloaca - virology dead animals diagnostic techniques disease detection disease surveillance Genetic diversity H5N1 avian influenza histopathology Hong Kong Incidence Influenza A virus Influenza A Virus, H5N1 Subtype - isolation & purification Influenza in Birds - epidemiology Influenza in Birds - mortality microbial genetics molecular sequence data mortality nucleotide sequences pathogen identification polymerase chain reaction reverse transcriptase polymerase chain reaction strains Trachea - virology vertebrate viruses virulence wild birds Wildfowl zoonoses China Hong Kong
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Summary:	Intensive surveillance of dead wild birds for H5N1 avian influenza infection is conducted in Hong Kong. Between January 2006 and October 2007 pooled cloacal and tracheal swabs from 17692 dead wild birds (from 16 different orders including 82 genera) were tested and 33 H5N1 highly pathogenic avian influenza viruses were isolated. No H5N1 infection has occurred in poultry farms since January 2003, or in live poultry markets in Hong Kong since November 2003 until a recent detection of H5N1 virus by surveillance of live poultry markets in June 2008. The gross and histopathology in the various H5N1-infected avian species is described, along with the performance of the virus isolation and polymerase chain reaction (PCR) tests used. This evaluation also included determination of virus titres and detection limits for the H5 haemagglutinin gene (H5)and matrix gene real-time reverse-transcription PCR tests in cloacal and tracheal swabs from 12 wild birds. The viruses isolated belonged to Clades 2.3.2 and 2.3.4, and within Clade 2.3.4 some clustering was evident based on H5 haemagglutinin gene haemagglutinating sequencing. There were no differences in the pathology findings between these subgroupings and the various diagnostic tests gave similar results for these viruses, except for a loss in sensitivity of the H5 real-time reverse-transcription PCR for several viruses in one cluster from birds submitted in February 2007. The use of multiple test methods was important in maintaining the diagnostic sensitivity for detecting avian influenza viruses with high genetic variability.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Current address: School of Veterinary and Biomedical Studies, Murdoch University, South Street, Murdoch WA 6150, Australia
ISSN:	0307-9457 1465-3338
DOI:	10.1080/03079450902751855