H5N5 Bird Flu: First US Human Case Confirmed

Health authorities stressed that the “risk to the community remains low,” and added that this type of contagion does not mark a trend of transmission between people. The Washington Department of Health reported that the epidemiological investigation is ongoing and, so far, the most likely source of the infection is exposure to infected domestic birds that were in contact with wild birds.

H5N5 infection stands out among the various “bird flu” variants, particularly because this is the first time that this strain has been detected in a person, after having previously been identified only in animals.

According to data from the Centers for Disease Control and Prevention (CDC), to date there have been 71 cases of avian flu in humans in the United States, with only one death attributed to the H5N1 variant. The CDC maintains that there is no evidence of human-to-human transmission and that “the threat to public health remains at a low level,” reported Newsweek.

During a press conference on Friday, Scott Lindquest, Washington state epidemiologist, explained that “this case represents a learning curve for many of us in clinical medicine.” The official stressed that “it is the first case in the world reported with H5N5, and the first in humans in at least eight months.”

During the same intervention, Lindquest insisted on the need to maintain surveillance, especially in people directly or indirectly exposed to free-range animals.

The opinion of the experts
Infectious disease experts analyzed the scope of the episode. For William Schaffner, professor at Vanderbilt University School of Medicine, becoming infected with this viral subtype “is probably a single incident without widespread consequences for the population,” as he commented in an email collected by Newsweek.

The academic added that “this case reminds us that we must continue to be alert to all aspects related to influenza, since this virus undergoes mutations that can sometimes unleash global epidemics.”

For his part, Jatin Vyas, an infectious disease specialist at the Vagelos School of Medicine and Surgery at Columbia University, said in dialogue with the same media that “genetic rearrangements (changes in the genes that encode proteins) in the flu are common.” He clarified that this “does not mean that the severity of the disease increases, but we continue to deepen its study.”

The autumn and winter period increases the risks associated with avian flu, due to the migration of birds that facilitates the spread of the virus among various species, especially in poultry farms. “This year, the outbreak started earlier and more severely,” Vyas told Newsweek.

The CDC report indicates that since February 2025, no new human cases of avian flu had been reported in the country. Months ago, in January, the first death was recorded in the United States due to the H5N1 variant, originating in the state of Louisiana.

Maurice Pitesky, a veterinarian at the University of California, Davis, pointed out the need to continue the analysis: “we will be interested in knowing if this H5N5 is the same one that circulates in Asian migratory routes. We would have to wait for the results of genetic sequencing to determine its origin,” he said in statements reported by Newsweek.

Given the appearance of the case, the Washington State Department of Health recommended that those who have domestic poultry avoid contact with sick or dead animals and report any suspected case to the Washington State Department of Agriculture by calling 1-800-606-3056 or through the official website.