Bird flu has reached new corners of the globe and become endemic for the first time in some wild birds that transmit the virus to poultry, according to veterinarians and disease experts, who warn it is now a year-round problem.

More than 20 experts and farmers on four continents said the prevalence of the virus in the wild signals that record outbreaks will not abate soon on poultry farms, ramping up threats to the world's food supply. They warned that farmers must view the disease as a serious risk all year, instead of focusing prevention efforts during spring migration seasons for wild birds.

Outbreaks of the virus have widened in North and South America, Europe, Asia and Africa, undefeated by summer heat or winter cold snaps, since a strain arrived in the United States in early 2022 that was genetically similar to cases in Europe and Asia.