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.

Hospitals should expand and speed up testing of people hospitalised with influenza to see if they are suffering from bird flu, according to the Centers for Disease Control and Prevention (CDC).