Russia said Saturday its scientists had detected the first case of transmission of the H5N8 strain of avian flu to humans and had alerted the World Health Organization.
In televised remarks, the head of Russia's health watchdog Rospotrebnadzor, Anna Popova, said scientists at the Vektor laboratory had isolated the strain's genetic material from seven workers at a poultry farm in southern Russia, where an outbreak was recorded among the birds in December.
The workers did not suffer any serious health consequences, she added.
"Information about the world's first case of transmission of the avian flu (H5N8) to humans has already been sent to the World Health Organization,", Popova said.
There are different subtypes of avian influenza viruses.
While the highly contagious strain H5N8 is lethal for birds it has never before been reported to have spread to humans.
Popova praised "the important scientific discovery," saying "time will tell" if the virus can further mutate.
"The discovery of these mutations when the virus has not still acquired an ability to transmit from human to human gives us all, the entire world, time to prepare for possible mutations and react in an adequate and timely fashion," Popova said.
People can get infected with avian and swine influenza viruses, such as bird flu subtypes A(H5N1) and A(H7N9) and swine flu subtypes such as A(H1N1).
According to the WHO, people usually get infected through direct contact with animals or contaminated environments, and there is no sustained transmission among humans.
H5N1 in people can cause severe disease and has a 60 percent mortality rate.
Located in Koltsovo outside the Siberian city of Novosibirsk, the Vektor State Virology and Biotechnology Center has developed one of Russia's several coronavirus vaccines.
In the Soviet era the top-secret lab conducted secret biological weapons research and still stockpiles viruses ranging from Ebola to smallpox.
Speaking in televised remarks, Vektor head Rinat Maksyutov said the lab was ready to begin developing test kits that would help detect potential cases of H5N8 in humans and to begin work on a vaccine.
The Soviet Union was a scientific powerhouse and Russia has sought to reclaim a leadership role in vaccine research under President Vladimir Putin.
Russia registered coronavirus vaccine Sputnik V in August, months before Western competitors and even before large-scale clinical trials.
After initial scepticism in the West, the Lancet journal this month published results showing the Russian vaccine - named after the Soviet-era satellite - to be safe and effective.
Avian flu has raged in several European countries including France, where hundreds of thousands of birds have been culled to stop the infection.