By Tanya Lewis, LiveScience Staff
Writer | LiveScience.com
They were dropping like flies.
One by one, the blackbirds started dying, with
no obvious cause. That year, 2001, the birds completely disappeared from
the city of Vienna.
The bird population rebounded a few years later,
but meanwhile, researchers at the University of Veterinary Medicine,
Vienna, started doing some detective
work. The team initially suspected West
Nile virus might have caused the blackbird die-off, but the tests
weren't conclusive.
A closer look revealed the killer was a related
pathogen called Usutu virus, but how it arrived in Vienna was a mystery.
Now, the scientists have identified that the virus first appeared
in Italy in 1996.
"This virus was not very well-known,
because it had never been related to any disease," study leaderand
pathologist Herbert Weissenböck told LiveScience. When it cropped up in
2001 in Vienna and other parts of Europe, "it was the causative agent of
huge avian mortality," he said.
Feathery surprise
Recently, Weissenböck and his colleagues at the
University of Veterinary Medicine, Vienna, learned of a similar mass dying
of blackbirds that took place in Tuscany, Italy, five years earlier,
in 1996. At the time, the cause was unknown, but scientists at the University
of Camerino saved tissue samples from the dead birds in paraffin wax.
Weissenböck's team analyzed the samples and
found the same strain of Usutu virus that had hit Vienna. "It was just a
guess, because the major species in Italy had been blackbirds as
well,"Weissenböck said.
The Vienna scientists sequenced the
genetic material from the Tuscany samples and samples from infected Vienna
birds, finding a match between the two viruses. A second test, using antibodies
for the virus, confirmed the match.
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