The CDC on Thursday urged labs nationwide to determine within 24 hours of admission whether people hospitalized with the flu have seasonal influenza or are infected with the bird flu that's behind an escalating outbreak in dairy cows and poultry.

The agency is advising enhanced safety measures in Minnesota and South Dakota, where turkey flocks with more than 500 birds should be isolated, monitored and tested for bird flu within 72 hours before going to slaughter,

The CDC announced on Thursday its recommendation to test hospitalized influenza A patients more quickly and thoroughly to distinguish between seasonal flu and bird flu.