A genetic analysis suggests the bird flu virus mutated inside a Louisiana patient who contracted the nation’s first severe case of the illness, the U.S. Centers for Disease Control and Prevention said this week.

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.

A genetic analysis of viral samples from a patient in Louisiana hospitalized with the first severe case of bird flu showed mutations that may result in the virus becoming more transmissible