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