“The report marks the 15th human case of an H5-type bird flu infection in the country since 2022. But, the case stands out—and is quickly generating alarm online—because the man reported no contact with animals. All 14 of the previous cases occurred in farmworkers who had contact with either dairy cows or poultry that were known to be infected with H5N1.”
I don’t think they’re necessarily saying it was spontaneous bird flu, it’s much easier to determine the animal(s) that gave a farm worker avian flu than testing every animal/person who interacted with someone.