A Washington state resident has been hospitalized and is ‘severely ill’ with a strain of virus that has never before been confirmed in humans.

The patient, an older adult with underlying conditions, was hospitalized with a strain of bird flu in early November after suffering from a high fever, confusion and severe breathing difficulties, officials said.

They were first treated by doctors in Grays Harbor County, about 100 miles west of Seattle, before being transferred to an unnamed hospital in King County, where Seattle is based, for specialist care.

Lab tests confirmed the patient was infected with H5N5, a strain of bird flu previously detected in animals but never before recorded in humans.

Where the strain could be determined, all previous human cases have been infected with the H5N1 strain. Experts said the appearance of this strain in humans showed the virus’s ‘unpredictable’ evolution. There is currently no evidence, however, that this strain is more infectious or severe in humans than other strains of the virus.

The case marks the first bird flu infection detected anywhere in the US in at least eight months, and the first recorded in Washington state this year.

Since the bird flu outbreak began in January 2022, a total of 71 people have been infected, and one individual, a person in Louisiana, has died. Only four cases have been detected so far this year