A rare and severe case of bird flu in Louisiana has led to a genetic mutation in the virus, prompting cautious attention from health experts. The U.S. Centers for Disease Control and Prevention (CDC) confirmed the mutation after analyzing samples from a patient over 65 years old who had underlying health conditions. The individual was hospitalized with severe respiratory symptoms after exposure to sick and dead birds in a backyard flock.
According to the CDC, the mutation affects the H5N1 strain of bird flu, increasing its ability to bind to cell receptors in the human upper respiratory tract. This development, while significant, appears to have occurred during the virus’s replication within the critically ill patient. Importantly, no evidence suggests that this mutated strain has spread to other humans or is circulating in bird populations.
While the mutation may enhance the virus’s ability to infect human cells, it does not indicate an imminent pandemic risk. Dr. Michael Osterholm, an infectious disease expert from the University of Minnesota, explained that the mutation allows the virus to fit better into human cell receptors but does not enable efficient human-to-human transmission. “This is a key that sits in the lock, but it doesn’t open the door,” Osterholm said, emphasizing the need for continued surveillance.
Other experts echoed this sentiment. Angela Rasmussen, a virologist at the University of Saskatchewan, noted that similar mutations have occurred in past cases without triggering outbreaks. Thijs Kuiken, a researcher at Erasmus University Medical Center, highlighted that while attachment to upper respiratory tract cells is necessary for transmissibility, it is just one of many steps required for a virus to spread efficiently among humans.
The CDC maintains that the overall risk to the public remains low. However, it acknowledges the need for vigilance given the widespread circulation of H5N1 in birds and its sporadic transmission to humans.
The U.S. has recorded 65 confirmed human cases of bird flu in 2024, with most infections linked to poultry or dairy farms. Experts warn that the extensive circulation of the virus increases the risk of it mixing with seasonal influenza strains, which could accelerate its evolution. Rasmussen compared this scenario to the origins of the 1918 and 2009 flu pandemics.
Meanwhile, reports of H5N1 infections in cats have raised additional alarms. In Oregon, a cat died after consuming raw pet food contaminated with the virus. Genome sequencing confirmed the strain in the food matched that found in the cat. Similar incidents have occurred, including the deaths of 20 big cats at a Washington sanctuary.
Ryan Scholz, a state veterinarian in Oregon, noted that the infected cat had no environmental exposure to the virus, underscoring the risks posed by contaminated pet food. Experts caution that outdoor cats, if infected by consuming infected birds, could pose a risk to humans through close contact.
The CDC and other health organizations are closely monitoring these developments. While the mutation in Louisiana’s patient is not an immediate cause for alarm, experts stress the importance of continued surveillance and preparedness. “The pandemic clock is ticking,” Osterholm said, “but we don’t know what time it is.”
