In mid-August, the [avian flu] survivors will start returning to their winter ranges, which stretch from eastern Europe to Australia and Alaska, and overlap with the ranges of other migrants. Mundkur cautions that it is not known how many birds from Qinghai Lake migrate to the farthest reaches of their species’s known ranges. But if some birds carrying the virus remain healthy enough to migrate, the disease could spread far and wide...
What is not clear is whether the Qinghai virus is any more deadly to wild birds than the other H5N1 variants that have killed wild birds. The Qinghai outbreak might merely be the first time that H5N1 has had the opportunity to infect such a large number of wild fowl.
“Any susceptible migrant could pick up the virus and die in the wild without being noticed,” says Mundkur. “It is only because the birds were congregating in a place that is visited, that the mass die-off was reported at Qinghai.”
Nor is it known if the Qinghai virus could kill humans. It does have a mutation associated with increased deadliness in mammals – Gao found that it kills all mice infected with it in four days – but this mutation may not be enough to make the virus dangerous for humans.
What is certain is that if the virus spreads to other countries, it will decimate poultry industries. The sequence also shows that H5N1 viruses in Asia are swapping genes – which could give rise to a virus capable of causing a human pandemic.
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