H5N8 has been isolated in seven workers on a Russian poultry farm in what is the first recorded case of the avian influenza variant passing to humans.
In December last year, an outbreak of H5N8 was discovered on a poultry farm in the Astrakhan region, in the south-west of the country.
As part of control measures, some 600,000 birds were culled in line with international guidelines, Russian authorities said.
But seven employees at the plant reported sore throats, for which they received outpatient care.
Anna Popova, the head of Russian public health authority Rospotrebnadzor, said the genetic material of H5N8 had been isolated, but there was no evidence of transmission between the workers.
She added that the incident had been reported to the World Health Organisation (WHO).
A WHO spokesperson said that, if confirmed, it would be the first time H5N8 had infected humans.
“WHO has been notified by the Russian Federation about human infection with avian influenza H5N8 through International Health Regulation mechanisms.
Preliminary information indicates that the reported cases were workers exposed to bird flocks.
“They were asymptomatic, and no onward human to human transmission was reported.
“If confirmed, this would be the first time H5N8 infects people.
“We are in discussion with national authorities to gather more information and assess the public health impact of this event. “
A Defra spokesperson said: “We are aware of media reports that the H5N8 strain of avian flu has been detected in humans and are working with the World Health Organisation to obtain more information.
“While the risk to the public’s health from the avian influenza virus strains found in England is very low, people should continue to avoid contact with dead or sick wild birds and bird keepers should maintain biosecurity measures on their premises.”
Most strains of avian influenza do not infect humans, though some variants are of concern.
Those that have passed from bird to human usually do so because of close contact with an infected animal.