Eco-virological approach for assessing the role of wild birds in the spread of avian influenza H5N1 along the Central Asian Flyway.

Charles M Bishop,Nichola J Hill,Patrick J Butler,Scott H Newman,Igor O Voronkin,Diann J Prosser,Baoping Yan,Nyambayar Batbayar,John Y Takekawa,Martin Wikelski,Sivananinthaperumal Balachandran,David C Douglas,Kyle A Spragens,Daniel Janies,Taej Mundkur,Tseveenmyadag Natsagdorj,Fumin Lei

doi:10.1371/journal.pone.0030636

Abstract

A unique pattern of highly pathogenic avian influenza (HPAI) H5N1 outbreaks has emerged along the Central Asia Flyway, where infection of wild birds has been reported with steady frequency since 2005. We assessed the potential for two hosts of HPAI H5N1, the bar-headed goose (Anser indicus) and ruddy shelduck (Tadorna tadorna), to act as agents for virus dispersal along this ‘thoroughfare’. We used an eco-virological approach to compare the migration of 141 birds marked with GPS satellite transmitters during 2005–2010 with: 1) the spatio-temporal patterns of poultry and wild bird outbreaks of HPAI H5N1, and 2) the trajectory of the virus in the outbreak region based on phylogeographic mapping. We found that biweekly utilization distributions (UDs) for 19.2% of bar-headed geese and 46.2% of ruddy shelduck were significantly associated with outbreaks. Ruddy shelduck showed highest correlation with poultry outbreaks owing to their wintering distribution in South Asia, where there is considerable opportunity for HPAI H5N1 spillover from poultry. Both species showed correlation with wild bird outbreaks during the spring migration, suggesting they may be involved in the northward movement of the virus. However, phylogeographic mapping of HPAI H5N1 clades 2.2 and 2.3 did not support dissemination of the virus in a northern direction along the migration corridor. In particular, two subclades (2.2.1 and 2.3.2) moved in a strictly southern direction in contrast to our spatio-temporal analysis of bird migration. Our attempt to reconcile the disciplines of wild bird ecology and HPAI H5N1 virology highlights prospects offered by both approaches as well as their limitations.

Highlights

Avian influenza virus of the highly pathogenic subtype H5N1, continues to pose a pandemic threat more than a decade after the virus first emerged in 1996 [1]
As a step towards assessing the role of wild birds in the dispersal of HPAI H5N1 from South to East Asia, we developed an ecovirological approach that utilized tools from the disparate fields of ecology and virology
Migration ecology In total, 97 bar-headed geese were marked with GPS satellite transmitters; from India, 1 from Nepal, from China and 39 from Mongolia

Summary

Introduction

Avian influenza virus of the highly pathogenic subtype H5N1 (or ‘HPAI H5N1’), continues to pose a pandemic threat more than a decade after the virus first emerged in 1996 [1]. The virus has not yet gained capacity for rapid human-to-human transmission but shows high fatality rates in humans (60%) [2]. It has become endemic in Indonesia, Bangladesh, India and Egypt with repeated emergence in China, Vietnam, Thailand and Mongolia [3]. HPAI H5N1 remains a significant threat to the poultry industry, destabilizing agriculture in countries where backyard farming of domestic ducks is common [4] and impacting the food security and livelihood of millions of people. The role of wild and domestic birds in the transmission of HPAI H5N1 depends on temporal and regional contexts and is currently far from clear [16]

Methods

Results

Conclusion