Risk-based surveillance of avian influenza in Australia’s wild birds

John P. Tracey

doi:10.1071/WR09152

RESEARCH ARTICLE (Open Access)

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Risk-based surveillance of avian influenza in Australia’s wild birds

John P. Tracey

+ Author Affiliations

- Author Affiliations

Invasive Animals Cooperative Research Centre, Vertebrate Pest Research Unit, Industry & Investment NSW, Forest Road, Orange, New South Wales 2800, Australia. Email: john.tracey@industry.nsw.gov.au

Wildlife Research 37(2) 134-144 https://doi.org/10.1071/WR09152
Submitted: 4 November 2009 Accepted: 8 February 2010 Published: 16 April 2010

Abstract

Context. The epidemiology of avian influenza and the ecology of wild birds are inextricably linked. An understanding of both is essential in assessing and managing the risks of highly pathogenic avian influenza (HPAI).

Aims. This project investigates the abundance, movements and breeding ecology of Australia’s Anseriformes in relation to the prevalence of low-pathogenicity avian influenza (LPAI) and provides risk profiles to improve the efficiency and relevance of wild-bird surveillance.

Methods. Generalised linear models and analysis of variance were used to examine the determinants of Anseriformes abundance and movements in Australia, and the observed prevalence of LPAI in Australia (n = 33 139) and overseas (n = 93 344). Risk profiles were developed using poultry density, estimated LPAI prevalence, the abundance of Anseriformes, and the probability of Anseriformes moving from areas of HPAI epizootics.

Key results. Analysis of Australian wild-bird surveillance data strongly supports other studies that have found the prevalence of LPAI in wild birds to be much lower (1%) in Australia than that in other countries (4.7%). LPAI prevalence was highly variable among sampling periods and locations and significantly higher in dabbling ducks than in other functional groups. Trends in Anseriformes movements, abundance and breeding are also variable, and correlated with rainfall, which could explain low prevalence and the failure to detect seasonal differences in LPAI in wild birds. Virus prevalence of faecal samples was significantly lower, whereas collecting faecal samples was 3–5 times less expensive and logistically simpler, than that of cloacal samples. Overall priority areas for on-going surveillance are provided for Australia.

Conclusions. Previous surveillance has occurred in high-priority areas, with the exception of Mareeba (North Queensland), Brisbane and Darwin, and has provided valuable information on the role of wild birds in maintaining avian influenza viruses. However, several practical considerations need to be addressed for future surveillance.

Implications. Long-term surveillance studies in wild birds in priority areas are required, which incorporate information on bird abundance, age, behaviour, breeding and movements, particularly for dabbling ducks. This is important to validate trends of LPAI prevalence, in understanding the main determinants for virus spread and persistence, and in predicting and managing future epizootics of HPAI in Australia.

Acknowledgements

I am indebted to Glen Saunders, Peter Fleming (Industry and Investment NSW), Rupert Woods, Leesa Haynes, Tiggy Grillo (Australian Wildlife Health Network), Chris Bunn (Department of Agriculture Fisheries and Forestry), Tony Peacock (IACRC) and Brian Boyle (Game Council NSW) for their on-going support and for collaborating on aspects of this project, and Camilla Myers for suggesting this paper. Thanks also go to Brian Lukins, Franz Zikesch, Megan Moppett, Brent Waldron, Shannon Slade and Game Council NSW for assistance with bird sampling; Peter Kirkland and Edla Arzey for testing samples; Remy van de Ven and Steven McLeod for valuable advice on data analysis; the staff of the Vertebrate Pest Research Unit for advice and technical support, and Simone Warner, David Roshier, Phil Hansbro and the Avian Influenza Wild Bird Steering Group for useful discussions. Thank you to David Drynan and Andrew Silcocks and many participants of Birds Australia Atlas, the Australian Bird Count Data and the Australian Bird and Bat Banding Scheme for collecting and collating data on anatids, in particular Greg Hocking, Clive Minton, Roz Jessop, Victorian Wader Study Group, Australasian Wader Study Group, Raoul Mulder and Patrick-Jean Guay. Thank you to Iain East and Graeme Garner (Department of Agriculture Fisheries and Forestry) for advice on Australian commercial poultry operations. Funding was provided by the Wildlife and Exotic Disease Preparedness Program, Industry and Investment NSW and the Invasive Animals Cooperative Research Centre.

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