Surveillance for highly pathogenic avian influenza in migratory shorebirds at the terminus of the East Asian-Australasian Flyway

Abstract

AIM: To determine if migratory birds arriving in New Zealand in the Southern Hemisphere spring of 2004 were infected with the highly pathogenic avian influenza (AI) virus, H5N1.

METHODS: Cloacal and faecal samples were collected from migratory red knots following their arrival in New Zealand in October 2004. Two species of resident sympatric birds, wrybill and mallard duck, were sampled prior to, and following, the arrival of migratory birds.

RESULTS: No AI viruses were isolated from migratory or resident shorebirds. Non-pathogenic AI viruses were isolated from six resident mallard ducks, comprising the endemic subtypes H4 (n=2), H7 (non-pathogenic), H10, and H11 (n=2).

CONCLUSIONS: Highly pathogenic AI H5N1 virus was not detected in migratory shorebirds or sympatric water birds in the Firth of Thames, New Zealand, in 2004-2005, despite the possible proximity of migratory birds to outbreaks of the disease in East Asia in 2004.

KEY WORDS::

• Surveillance
• highly pathogenic avian influenza
• H5N1 virus
• low-pathogenic avian influenza
• migratory shorebirds
• East Asian-Australasian Flyway
• mallard ducks

Acknowledgements

The authors would like to especially thank members of the OSNZ, Fish and Game New Zealand, and all the volunteers who assisted with sampling. We thank David Melville and Dr Phil Battley, ornithologists of Blenheim and Palmerston North, respectively, and Dr Ken Shortridge, virologist, Auckland, for their valuable advice. The inter-agency group of the Ministry of Agriculture and Forestry, the Ministry of Health, and the Department of Conservation funded this project through the Cross-Departmental Research Pool.