The Bird Flu Virus That Has Infected People in Russia

New strains of influenza are constantly emerging. Although the virus is associated with winter epidemics of respiratory disease in people, wild migratory birds are flu’s main target -- and are responsible for much of its global distribution. An avian flu variant that’s been spreading in wild birds and occasionally spilling over and killing poultry for years recently caused the first reported human infections in southern Russia. Authorities have found no sign this particular virus is being transmitted from person to person. But new strains capable of infecting people raise concern because of the potential for them to mutate and become better suited to human respiratory tracts, potentially sparking dangerous epidemics.

Five women and two men aged 29 to 60 were infected with the H5N8 strain of bird flu while responding to an outbreak on an egg-producing farm in the administrative region of Astrakhan in December 2020. Some 101,000 of 900,000 hens died on the farm from Dec. 3-11, according to the World Health Organization. The affected workers developed no illness as a result of the infection, the WHO said on Feb. 26, contradicting a report by state media five days earlier that said the employees developed a sore throat. All are now in good health, after “the disease ended rather quickly,” Anna Popova, the country’s public-health chief, told reporters on Feb. 20, adding that the virus spurred an immune response in those infected. All close contacts of the seven cases were monitored, and no one showed signs of clinical illness, the WHO said.