A genetic analysis suggests the bird flu virus mutated inside a Louisiana patient who contracted the nation’s first severe case of the illness, federal health officials said this week.
The CDC said changes seen in the person were not present in the virus samples obtained from the birds, suggesting that mutations developed during the person’s infection.
What Researchers Say
Michael Osterholm, a University of Minnesota infectious disease researcher, likened this binding interaction to a lock and key. To enter a cell, the virus needs to have a key that turns the lock, and this finding means the virus may be changing to have a key that might work.“Is this an indication that we may be closer to seeing a readily transmitted virus between people? No,” Osterholm said. “Right now, this is a key that sits in the lock, but it doesn’t open the door.”
Angela Rasmussen, a virologist who specializes in infectious diseases, wrote that “more [genetic] sequences from humans is a trend we need to reverse” and that “we need fewer humans infected” by bird flu.
She said the Louisiana “patient was infected by the birds, but because the bird viruses don’t have these sequences, it’s likely they emerged in the human host,” which she called “good news.”
“It reduces the risk of transmission to another person and suggests ‘human-adapted’ viruses aren’t emerging in birds,” Rasmussen said.
She cautioned that “there has been an explosion of human cases” and that “we don’t know what combination of mutations would lead to a pandemic H5N1 virus … but the more humans are infected, the more chances a pandemic virus will emerge.”
“We kind of have our head in the sand about how widespread this is ... from the animal-to-human standpoint,” she said.
Scott Gottlieb, a former U.S. Food and Drug Administration (FDA) commissioner and Pfizer board member, wrote on X that “most believe it’s unlikely H5N1 will develop into a pandemic, but in a low-probability scenario it does, the U.S. will have only itself to blame.”
Outbreak Risk Remains Low
In its report, the CDC said the Louisiana patient was exposed to sick and dead birds in backyard flocks and that the risk of a U.S. outbreak is still low. So far, there have been 65 confirmed human cases of H5N1 avian influenza across the United States in 2024, while the CDC has confirmed that 891 dairy herds have been impacted by the virus.“The detection of a severe human case with genetic changes in a clinical specimen underscores the importance of ongoing genomic surveillance in people and animals, containment of avian influenza outbreaks in dairy cattle and poultry, and prevention measures among people with exposure to infected animals or environments,” the agency said.
The virus has been causing sporadic, mostly mild illnesses in people in the United States, and nearly all of those infected worked on dairy or poultry farms. The Louisiana patient who developed a severe form of the disease is over age 65 and had underlying medical issues, said the CDC earlier this month.
The CDC has stressed there has been no known transmission of the virus from the Louisiana patient to anyone else.
In November, Canadian officials reported that a teen in the province of British Columbia was hospitalized with a severe case of avian flu.
CDC Recommendations
The CDC website recommends that people should “avoid direct contact with wild birds and observe them only from a distance, if possible,” and they are advised to “avoid contact with wild or domestic birds that appear ill or have died and call to report sick or dead birds.”People are also advised not to consume raw or unpasteurized milk or products made from raw milk, according to the CDC.
Bird Flu Can Spread to Cats
The death of an Oregon house cat and a pet food recall this week have raised questions about the ongoing outbreak.Oregon health officials traced the cat’s illness to frozen cat food that contained raw turkey. The virus recovered from the recalled pet food and the infected cat matched. At the same time, the Los Angeles County Department of Public Health is investigating the deaths of four house cats that drank recalled raw milk.
Northwest Naturals, a pet food company in Portland, Oregon, announced a voluntary recall Tuesday of one batch of its 2-pound Feline Turkey Recipe raw frozen pet food after it tested positive for the virus.
Emergency Declared in California
Earlier in December, California Gov. Gavin Newsom declared an emergency over bird flu in his state, suggesting that the move was precautionary in nature.His office said bird flu cases have been discovered in dairy cows in Southern California and added that enhanced monitoring is needed to “contain and mitigate the spread of the virus.”
“This proclamation is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak,” the governor said in a Dec. 18 statement about the emergency order.
