The CDC is now calling for subtyping of influenza A viruses in all hospitalized patients -- and on an accelerated timeline, ideally within 24 hours. Nirav Shah, MD, JD, principal deputy director of the CDC,

The US Centers for Disease Control and Prevention is urging hospitals to accelerate advanced testing of people they suspect may have bird flu.

The risk to the general public from bird flu is low, and there has been no further evidence of person to person spread, the agency said. Influenza A-positive patients, particularly those in an intensive care unit,

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.

CDC officials say medical professionals are seeing more patients whose illness cannot be traced back to an infected animal or bird.

CDC officials say they extended the guidance now because they are seeing more H5N1 patients whose illness they cannot track back to an infected bird or cow.