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.

Officials from the Centers for Disease Control and Prevention (CDC) recommend that hospitals speed up testing people who are hospitalized with the flu for H5N1 bird flu. Health care workers in hospitals are urged to perform additional testing on patients hospitalized with influenza A — ideally within 24 hours of admission — to determine

People hospitalized for flu should be tested for bird flu within 24 hours, the U.S. Centers for Disease Control and Prevention said on Thursday, in an expansion of the agency's efforts to tackle increasing infections in humans.

The Centers for Disease Control and Prevention says hospitals treating people for the flu should test them for avian influenza within 24 hours.

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.

The CDC is calling for expanded testing of bird flu after a child in California tested positive for the virus despite no known contact with animals.