Israel detected its first cases of H5N1 bird flu on Friday, saying the virus had killed thousands of turkeys and chicken on two farms, and hospitalized three people suspected of being infected. Bird flu has spread with alarming speed in recent weeks across Europe, Africa and parts of Asia, stoking fears the virus could mutate into a form that could easily pass from one person to another, triggering a pandemic in which millions could die. Three people who worked in poultry coops at the farms where the virus was discovered were admitted to isolation units at Soroka Medical Center in the southern Israeli city of Beersheba.