The CDC has confirmed a total of 66 human cases of bird flu across the United States as of Friday, although the number is believed to be higher.

A genetic analysis of samples from the patient in Louisiana recently hospitalized with the country’s first severe case of H5N1 bird flu show the virus likely mutated in the patient to potentially become more transmissible to humans,

The CDC said that testing of a person with a severe case of bird flu indicated the virus had mutated but the risk remains low to the public as no human-to-human transmission has been documented.