H5N1 spreading in animals
Researchers say new H5N1 mutations are helping the virus infect cows more easily by targeting mammary glands, while not yet showing evidence of increased human risk. (unmc.edu). Scientists also mapped the rapid, continent‑wide expansion of genotype D1.1 in North American wild birds during the 2024 migration, indicating the strain is now well‑established in wild reservoirs. (nature.com)(prnewswire.com). Outbreaks continue: Ivory Coast reported about 95,000 poultry deaths, Britain confirmed three cases days after lifting housing rules, and WHO tallies show nearly 1,000 confirmed human H5N1 infections since 2003 with more than 450 deaths. (devdiscourse.com)(farminguk.com)(threads.com)
Bird flu is changing in animals again: researchers say one H5N1 version now infects cows more easily, while another has spread widely through North American wild birds. (unmc.edu) Influenza infects cells by latching onto sugars on their surface, like a key fitting a lock. A report published April 15 said some H5N1 viruses in dairy cattle now bind better to a cattle sugar called N-glycolylneuraminic acid, or NeuGc, which is found in cow mammary tissue but not in humans or birds. (unmc.edu) That change helped the virus infect and grow in cow mammary tissue more efficiently in lab work, according to researchers cited by the University of Nebraska Medical Center. The same report said the adaptation did not appear to increase the virus’s ability to target human-type receptors. (unmc.edu) A separate paper in Nature Medicine tracked genotype D1.1 during the 2024 fall migration and found it spread rapidly across Canada and the United States in wild birds. The authors said D1.1 formed a single lineage and displaced earlier H5 genotypes across several flyways. (nature.com) Wild birds matter because they move the virus long distances and keep reseeding farms and other animals. The United States Department of Agriculture says H5N1 is present in wild birds worldwide and is causing outbreaks in domestic birds and dairy cattle. (aphis.usda.gov) Public health agencies are drawing a line between animal spread and human risk. The Centers for Disease Control and Prevention said on March 6 that H5 bird flu is widespread in wild birds, poultry, and United States dairy cows, but the current public health risk remains low and there is no known person-to-person spread. (cdc.gov) Human infections are still rare, but they are not new. The World Health Organization’s cumulative table, updated with data through January 22, 2026, shows 973 confirmed H5N1 cases and 470 deaths reported since 2003. (who.int) Outbreaks in birds are continuing on multiple continents. Ivory Coast reported about 95,000 poultry deaths in the town of Vridi, and British poultry authorities confirmed three new cases after mandatory housing measures in England and Wales were lifted on April 9. (devdiscourse.com) (gov.uk) (farminguk.com) In the United States, the cattle outbreak first reported on March 25, 2024, was the first time these bird flu viruses had been found in cows. The Centers for Disease Control and Prevention says people with job-related exposure to infected birds or animals, including cows, face higher risk than the general public. (cdc.gov) The immediate question is no longer whether H5N1 can move through animal populations. It is how long health agencies can keep tracking a virus that is now entrenched in wild birds and has found a more efficient foothold in dairy cattle. (nature.com) (cdc.gov)
