Bird flu fears As US marks first H5N1 bird flu death, WHO and CDC say risk remains low No human-to-human spread identified and no concerning mutations circulating. Beth Mole Jan 7, 2025 6:14 pm | 11 A colorized image shows H5N1 avian flu strain viruses (gold) grown in dog kidney cells (green). Credit: uafcde A colorized image shows H5N1 avian flu strain viruses (gold) grown in dog kidney cells (green). Credit: uafcde Story textSizeSmallStandardLargeWidth *StandardWideLinksStandardOrange* Subscribers only Learn moreThe H5N1 bird flu situation in the US seems more fraught than ever this week as the virus continues to spread swiftly in dairy cattle and birds while sporadically jumping to humans.On Monday, officials in Louisiana announced that the person who had developed the country's first severe H5N1 infection had died of the infection, marking the country's first H5N1 death. Meanwhile, with no signs of H5N1 slowing, seasonal flu is skyrocketing, raising anxiety that the different flu viruses could mingle, swap genetic elements, and generate a yet more dangerous virus strain.But, despite the seemingly fever-pitch of viral activity and fears, a representative for the World Health Organization today noted that risk to the general population remains lowas long as one critical factor remains absent: person-to-person spread."We are concerned, of course, but we look at the risk to the general population and, as I said, it still remains low," WHO spokesperson Margaret Harris told reporters at a Geneva press briefing Tuesday in response to questions related to the US death. In terms of updating risk assessments, you have to look at how the virus behaved in that patient and if it jumped from one person to another person, which it didn't, Harris explained. "At the moment, we're not seeing behavior that's changing our risk assessment," she added.In a statement on the death late Monday, the US Centers for Disease Control and Prevention emphasized that no human-to-human transmission has been identified in the US. To date, there have been 66 documented human cases of H5N1 infections since the start of 2024. Of those, 40 were linked to exposure to infected dairy cows, 23 were linked to infected poultry, two had no clear source, and one casethe fatal case in Louisianawas linked to exposure to infected backyard and wild birds."Additionally, there are no concerning virologic changes actively spreading in wild birds, poultry, or cows that would raise the risk to human health," the CDC said.Ongoing threatIn its own announcement of the death, the Louisiana health department noted that the person who was infected was over the age of 65 and had underlying medical conditions, which made the person particularly vulnerable to severe disease.A 13-year-old girl in Canada also developed severe disease from an H5N1 infection in November and required intensive care, intubation, and the use of the life-support therapy extracorporeal membrane oxygenation (ECMO). The teenager is, fortunately, recovering, according to a medical report published December 31 in the New England Journal of Medicine.But, fatalities are not uncommon with H5N1 infections overall. According to data collected by the WHO, there have been 954 documented cases between 2003 and 2024. Of those, 464 were fatal, leading to a fatality rate of about 49 percent among documented cases.Without sustained human-to-human transmission or other dangerous changes to the virus, the risk to the general population remains low. But, both the CDC and Harris emphasized that people who work with birds and other animals are at greater risk of infection and should take precautions. Since March, at least 919 dairy herds across 16 states have been infected with H5N1, 703 of which have been in California. Since January 2022, over 130 million birds have been affected.With the continued spread in birds and other animals, the virus has more opportunities to adapt to humans. Health experts have criticized the US handling of the outbreaks and not doing more to curb the spread of the virus, which has moved seemingly unabated through dairy farms.Beth MoleSenior Health ReporterBeth MoleSenior Health Reporter Beth is Ars Technicas Senior Health Reporter. Beth has a Ph.D. in microbiology from the University of North Carolina at Chapel Hill and attended the Science Communication program at the University of California, Santa Cruz. She specializes in covering infectious diseases, public health, and microbes. 11 Comments