However, the number of cases in poultry flocks continues to increase across Great Britain and there is a heightened risk of transmission from wild to kept birds.
Fodd bynnag, mae nifer yr achosion mewn heidiau dofednod yn parhau i gynyddu ledled Prydain Fawr ac mae risg uwch o drosglwyddo o adar gwyllt i adar a gedwir.