Bird Flu In US: How Is The New H5N5 Strain Different From H5N1?

As bird flu continues to trouble several countries, health officials in the United States have reported the first known human case of the H5N5 subtype of avian influenza. The Washington State Department of Health announced on November 14, 2025, that the virus was found in a resident of Grays Harbor County. The patient, an older adult with existing medical issues, is currently in the hospital. Authorities noted that the individual kept poultry at home that had contact with wild birds, which is believed to be the likely source of the infection, though the investigation is still underway. Since H5N5 is newly identified in humans, many are asking whether it differs from the earlier H5N1 strain.What Is the H5N1 Strain?H5N1 is a highly pathogenic form of avian influenza that mainly affects birds