MOSCOW - A strain of avian influenza virus that can be lethal to humans has spread from Southeast Asia to poultry flocks in Russia and Kazakhstan, a scientific journal reported yesterday, leading a British researcher to warn that the virus may be approaching Europe.
"If we are seeing an expansion in range, that is something we should be concerned about," Ian Brown, head of avian virology at the United Kingdom Veterinary Laboratories Agency, told the journal Nature in an article published yesterday on its Web site.
A Kazakh man who works on a chicken farm recently fell ill with the symptoms of bird flu, Nature reported. The man lives in a village in the Pavlodar region of northeast Kazakhstan, near the Russian border.
An outbreak has killed 600 geese in the village. Nature reported that tests showed they were infected with the virulent H5N1 strain of the bird flu virus.
The virus has also been discovered in three regions of Siberia, but so far no suspected human cases have been reported in Russia.
Since late 2003, the H5N1 strain has sickened 109 people and killed at least 55 in Vietnam, Thailand, Cambodia and Indonesia. Outbreaks of the disease have also led to the culling and vaccination of tens of millions of domestic birds.
So far, most humans have contracted this particularly dangerous type of influenza from contact with birds.
But public health experts fear that the virus may evolve into a vastly more dangerous form that could be transmitted between people.
Dr. Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy, said it was too early to conclude whether the events reported in Nature represent a widening of the outbreak that has struck Southeast Asia.
"The fact of the matter is that H5N1 has been found in ducks around the world for some time," said Osterholm, who has warned that governments are ill-prepared for the next flu pandemic. "But it's been a different H5N1, genetically different from what's been found in Asia."
Osterholm said it's unclear whether new isolates are turning up because the disease is spreading or because scientists are sampling more birds.
The Russian outbreak began in mid-July when geese, chickens, ducks and turkeys began dying on farms in the village of Suzdalka, near Chany Lake, a migratory habitat in the Novosibirsk region. The outbreak spread to at least 13 nearby villages, where it has killed hundreds of domestic birds.
Russian agriculture officials said the poultry flocks probably contracted the bird flu from migratory waterfowl.
Poultry have also started dying of H5N1 in recent days in two other Russian regions, Tyumen' and the mountainous Altay oblast, the Health Ministry said yesterday.
About 450 domestic birds have died in the nearby Omsk region, according to the Itar-Tass news service. But officials are still trying to determine the cause of those deaths.
Confirmation of the arrival of the H5N1 strain in western Siberia came after repeated denials by Russian health officials.
A state virologist told the Interfax news service July 22 that a bird flu outbreak, first reported in Suzdalka, was of a type harmless to humans. On July 26, Gennady Onishchenko, the Health Ministry's chief epidemiologist, assured Russian news media that the strain of influenza found on Russian poultry farms could not sicken people.
Confirmation that the Siberian outbreak was caused by the H5N1 strain came Friday, in a Agriculture Ministry statement.
An aide said Onishchenko was away from Moscow and not available for comment.
The World Health Organization has urged governments to send bird flu samples to its labs to speed positive identification of the type of virus involved.
All of the affected areas in Russia are in south-central and southwestern Siberia, about 1,700 miles east of Moscow. All are being quarantined, Yevgeny Nepoklonov, a deputy head of the federal veterinary service, told NTV television yesterday.
A total of 2,707 domestic birds had died in the Russian outbreak, the Emergency Situations Ministry told the Associated Press. Health authorities have ordered the destruction of 65,000 birds in the 14 affected villages.
Even if the bird flu causes no human deaths, it could devastate Russia's booming poultry industry. Global health officials fear that bird flu will spread around the world in coming weeks as waterfowl begin their annual migrations.
Sun staff writer Jonathan Bor contributed to this article.