Mutated Bird Flu Virus Raises Concern After Being Found In US Patient

The Centers for Disease Control and Prevention (CDC) claim that the bird flu virus found in a severely ill American patient contains modifications that have improved its adaptation to human airways. Authorities did, however, clarify that there is no proof the altered virus is spreading outside of the individual.

The elderly patient is still in critical condition after being admitted to the hospital in Louisiana due to a severe H5N1 virus. A little portion of the virus in the patient’s throat had genetic alterations that might improve its capacity to attach to cell receptors in the human upper respiratory tract, according to the CDC’s analysis, which was published on its website on Thursday.

Notably, birds—including the backyard flock of chickens thought to have initially infected the patient—were not discovered to have these alterations. Rather, the CDC came to the conclusion that the changes most likely resulted from the virus multiplying inside the very sick patient.

“No transmission of the mutated virus to other humans has been identified,” the CDC stated.

The alteration may be a step toward simpler human-to-human transmission, but it is not definitive proof of a greater threat, virologists stressed.

“This is one step that is needed to make a more efficiently transmissible virus,” said Angela Rasmussen, a virologist at the University of Saskatchewan, “but it’s not the only step.” She added that further testing is required to determine if the mutation enhances the virus’s ability to enter human cells.

Prior instances of extremely sick bird flu patients have shown similar mutations without causing broad transmission. “It’s good to know that we should be looking out for this,” Rasmussen said, “but it doesn’t actually tell us, ‘Oh, we’re this much closer to a pandemic now.’”

She reiterated her warning, pointing out that effective binding to human respiratory cells is “necessary, but not sufficient” for prolonged human-to-human transmission, as stated by Thijs Kuiken of Erasmus University Medical Center in the Netherlands.

Rasmussen was more alarmed by the high prevalence of bird flu that is affecting the entire world. In 2024, the CDC recorded 65 verified human cases in the US, with many more among dairy and poultry workers probably going unreported.

Rasmussen cautioned that this extensive dissemination raises the possibility of “reassortment” of seasonal flu and bird flu viruses, which could result in swift evolutionary alterations. Past pandemics, such as those in 1918 and 2009, have been connected to such processes.