The CDC found two bird flu genetic mutations in a Chilean man who recently fell ill with the disease. The mutations show signs of the virus adapting to mammals, The New York Times reported April 14.
The mutations, both in the PB2 gene, help the virus, known as H5N1, replicate better in mammalian cells. However, health officials say the public risk remains low and no additional human cases were linked to the hospitalized man. The mutation likely emerged in the Chilean man over the course of his illness, according to the report.
"There are three major categories of changes we think H5 has to undergo to switch from being a bird virus to being a human virus," Richard Webby, a bird flu expert at Memphis, Tenn.-based St. Jude Children's Research Hospital, told the Times. "The sequences from the person in Chile have one of those classes of changes. But we also know that of those three sets of changes, this is the easiest one for the virus to make."
The other two mutations H5N1 would need to make include a mutation that would stabilize the virus and one that would help it bind more tightly to human cells.
Chile's Ministry of Health reported the man's case to the World Health Organization on March 29. The 53-year-old man is believed to have gotten the infection from birds or sea lions near his home. He is the 11th reported human case of H5N1 since January 2022.
A 56-year-old woman from China was reported to be the first human death from the H3N8 strain on April 11.