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Scientists say bird flu cases back migration theory
  Tue Oct 18, 2005 8:46 AM ET
By David Evans
PARIS (Reuters) - The discovery of bird flu in Romania and Turkey supports the theory the deadly virus is being spread by migrating wildfowl, scientists said on Tuesday.
Ever since the discovery in July that H5N1 bird flu, which has killed more than 60 people in Asia, had spread to birds in Siberia, experts have feared that migratory wildfowl would bring the virus westwards.
"These latest cases in Romania and Turkey have reinforced that theory," Alex Thiermann, President of the International Animal Health Code at the World Organization for Animal Health (OIE) in Paris, told Reuters.
H5N1 is particularly deadly for chickens and can wipe out a flock within hours. But wild water-birds such as ducks and geese can harbour the virus for long periods, most of the time showing no symptoms or becoming ill.
Whilst any bird can in theory become infected, wildfowl are the primary carriers, and many species fly south from Siberia seeking warmer climes at the onset of winter, scientists say.
"The existence of known migration flyways of several birds species connecting South East Asia, Siberia and Europe shows a possibility of the introduction of the H5N1 virus to both eastern and western Europe," the OIE said this week in a report on the outbreak in Russia.
It said surveillance should be increased in the Caspian Sea region, which was recognized as "a significant wintering area for water birds of various origins (Europe and western Asia) and can be considered as a so-called biological 'hub'."
What scares experts most is that the virus could mutate and pass easily between humans -- possibly sparking a pandemic to rival the killer global flu outbreaks of the last century.
The spread of bird flu in parts of Asia and earlier this year from Russia to Kazakhstan has also been linked to cross-border trade in live poultry, either legal or illegal.
Thiermann said the widespread practice of cock-fighting in Asia, where it was big business, may have played a role there.
But trade was an unlikely source of the latest cases.
"The role of migratory birds carrying the Asian H5N1 influenza virus under certain conditions to other parts of the world seems now more likely," the OIE said after the latest test results from Romania and Turkey.
The OIE and U.N. Food and Agriculture Organization (FAO) have pinpointed the Caspian and Black Sea regions, as well as the Balkans, as a "gateway to central Europe for the virus."
Bird migration routes also ran across Azerbaijan, Iran, Iraq, Georgia, Ukraine and some Mediterranean countries to Africa, where outbreaks were possible.
Didier Houssin, the French government official in charge of the country's bird flu defense, told Le Monde newspaper that migrating birds were the most likely source of transmission, using flyways between the Black Sea region and Mediterranean.
"This axis raises fears that pockets will emerge in the Middle East and then in Africa. It then becomes a very serious threat. One can imagine the virus becoming endemic in Africa as it is in several Asian countries," Houssin said.
"We'd be confronted with great difficulties in controlling the disease, and in a few months, with the threat of potentially infected birds flying back up to western Europe from Africa."
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