Bird flu prevention zone imposed in England / B.C. animal clinics told to set up avian flu protocols amid human exposure risk / B.C.'s chief vet tells clinics to set up avian flu protocols amid human exposure risk / Health experts raise concern over the disposal of infected poultry birds as avian flu spreads / Bird flu vaccines for laying hens prove effective in practice / A person in Texas tested positive for avian influenza after exposure to dairy cattle presumed to be infected with the H5N1 bird flu, the Centers for Disease Control said.