Turkey has reported an outbreak of the highly contagious H5N1 strain of avian influenza on a poultry farm for the first time in over a year, the World Organisation for Animal Health (WOAH) said on Monday.

The UK government said on Tuesday that cases of bird flu had been confirmed in commercial poultry at premises in Yorkshire, hours after it increased the risk level of the disease from medium to high.

The United States Department of Agriculture last week reported that a pig on a backyard farm in Oregon was infected with bird flu.

In many ways, the initial reports of this case are – against the backdrop of a continuing viral outbreak that has devastated seabird colonies around the world, caused huge die-offs of sea lions and led to the emergence of an entirely new disease of US dairy cattle – pretty innocuous.