WASHINGTON, Dec 28, 2024 (BSS/AFP) - The bird flu virus found in a severely
ill patient hospitalized in the United States has mutated to become better
adapted to human airways, though there is no evidence it has spread beyond
the individual, authorities said.

Earlier this month, officials announced an elderly Louisiana patient was in
"critical condition" with a severe H5N1 infection.

An analysis posted by the Centers for Disease Control and Prevention (CDC) on
its website Thursday found that a small percentage of the virus detected in
the patient's throat had genetic changes that may lead to "increased virus
binding" to certain "cell receptors found in the upper respiratory tract of
humans."

Importantly, these changes have not been found in birds, including in the
backyard poultry flock thought to have infected the Louisiana patient
initially.

Instead, the CDC stated that the mutations were "likely generated by
replication of this virus in the patient with advanced disease," adding that
no transmission of the mutated virus to other humans has been identified.

Experts contacted by AFP said it was too early to determine whether these
changes would make the virus spread more easily or cause more severe disease
in humans.

The particular mutation "is one step that is needed to make a more
efficiently transmissible virus," said Angela Rasmussen, a virologist at the
University of Saskatchewan in Canada. "But I do want to point out that it's
not the only step."

She explained that while the mutation might mean the virus can more easily
enter cells, this would need to be confirmed through further testing on
animals. Moreover, similar mutations have been found in severely ill patients
in the past without triggering wider spread among humans.

"It's good to know that we should be looking out for this," she said, "but it
doesn't actually tell us, 'Oh, we're this much closer to a pandemic now.'"

Another expert, Thijs Kuiken of Erasmus University Medical Center in the
Netherlands, agreed with Rasmussen.

"Efficient attachment to human upper respiratory tract cells is necessary,
but not sufficient, for more efficient transmissibility between people," he
said, "because the attachment process is but one of several steps in the
virus replication cycle in a human cell."

Rasmussen expressed greater concern about the overall level of bird flu
currently circulating rather than this specific case.

The CDC has reported 65 confirmed human cases of bird flu in the United
States in 2024, with more likely going undetected among dairy and poultry
workers.

This, Rasmussen explained, increases the chances of bird flu "reassortment"
with seasonal flu, which could lead to "rapid evolutionary leaps in a short
period of time," similar to the processes that caused the 1918 and 2009
pandemics.