By Leah Douglas and Tom Polansek (Reuters) -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 ongoing 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.

The CDC recommends that hospitalized flu patients be tested for bird flu within 24 hours to timely identify avian influenza A (H5N1) cases. While the public risk remains low, faster detection aids in tracing infections and providing swift medical response.

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.