US: Satellite tracking of wild birds in Asia suggests that they may be spreading H5N1 avian influenza from India or Tibet to Mongolia when they fly north in the spring, according to a recent report from the United Nations Food and Agriculture Organization (FAO).
This conclusion comes from the tracking of waterfowl that frequent China’s Qinghai Lake, where more than 6,000 wild birds died of H5N1 in 2005. Since that outbreak, researchers with the FAO and the US Geological Survey have mounted GPS transmitters on 525 waterfowl in 11 countries to track their migrations, the FAO said.
About half of the birds that died in the Qinghai Lake outbreak were bar-headed geese. The FAO said the satellite tracking has shown that most of the bar-headed geese tagged at Qinghai Lake spend their winters in the Lhasa region of Tibet or in India. There, wild birds are exposed to domestic poultry and since those areas have had H5N1 outbreaks, the virus may spread between domestic and wild birds, according to the FAO.
“If this is so, wild waterfowl on the eastern portion of the Central Asian Flyway may in fact be helping spread H5N1 HPAI [highly pathogenic avian influenza] into Mongolia each spring as they cross the Qinghai-Tibetan plateau to the north and east,” the report says.
“Most interesting is that this repeatable pattern of wild bird outbreaks at the northern end of their migration pathway each spring does not appear to be occurring in other major flyways, thus demonstrating the complexity surrounding the role of wild birds in the disease epidemiology,” it adds.
A chart in the FAO newsletter shows that Mongolia reported its first H5N1 outbreak in August 2005 and its latest one in May of this year. Reports from the World Organization for Animal Health (OIE) say that Mongolia also reported H5N1 outbreaks in 2009 and 2006. All outbreaks reported there have been in wild birds.
An FAO fact sheet on wildlife and H5N1 says that in 2009 large numbers of birds died at Qinghai Lake after the spring migration northward from India and Bangladesh and that more wild birds died weeks later at the northern end of the flyway in Mongolia and Russia, which “strongly supports the spread of the virus from infected wild birds.”
However, the fact sheet says the overall global pattern of avian flu spread since 2005 “suggests that wild birds are not the primary spreader of H5N1 HPAI but that human movement of virus through trade, marketing, and fomites likely accounts for the significant spread of the virus.”