A genetic mutation of the H5N1 bird flu virus — a mutation associated with increased infectiousness and disease severity — has been found in two cats, in what scientists say is another indication of the risks posed by the virus.

Health authorities say the threat of infection for people remained low even amid the spread of H5N1 virus among birds and cattle nationally.

Health officials urged pet owners not to let their felines roam outdoors or feed them raw food or raw milk — common ways avian influenza can be transmitted.