Testing of the latest human case of bird flu has revealed a “notable” mutation in the virus, officials have said.
The case, which was identified this month in a dairy worker in Michigan, marks the second human infection linked to the multi-state H5N1 outbreak among US cattle.
Genomic sequencing has now found a change in the virus compared to an earlier infection in a dairy worker in Texas, raising concerns that the virus is evolving to better infect humans.
The slight change in the virus’s genetic makeup is “associated with viral adaptation to mammalian hosts,” the Centre for Disease Control said in a statement published on Friday.
This change has also been identified as resulting in enhancement of virus replication and disease severity in mice during studies with avian influenza viruses, the agency added.
“This is exactly why I’ve been trying to call attention to deep sequencing of each virus from cows, cats, and people infected with H5N1, which is needed for a rapid and effective global response on vaccine and antiviral development,” said Dr Rick Bright, an immunologist and influenza expert, on X (formerly Twitter).
Despite the virus’s evolution, the CDC stressed the strain is still closely related to the clade of H5N1 circulating in US dairy cattle, and closely matches the two candidate vaccines currently available to manufacturers, should they be needed.
Experts think it likely that we will begin to see more human cases of H5N1 in dairy workers in the coming weeks and months, as surveillance efforts ramp-up across America.
