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

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.

Officials from the Centers for Disease Control and Prevention recommend that hospitals speed up testing people who are hospitalized with the flu for H5N1 bird flu. Healthcare workers in hospitals

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.

The CDC advises testing hospitalized flu patients for bird flu within 24 hours to prevent delays in identifying human infections. While the public risk remains low, nearly 70 Americans have contracted bird flu.

We last spoke in April, after a dairy worker became infected with bird flu. At the time, you described your level of concern about bird flu as “medium.” How would you describe your level of worry now?