First Human Case of Bird Flu Subtype H5N5 Reported in Washington State

A human infection with the avian influenza subtype H5N5 has been confirmed by health authorities in the state of Washington, United States. The case involves an individual from Grays Harbor County who was hospitalized earlier this month after exhibiting flu-like symptoms. Laboratory testing subsequently identified the H5N5 virus, a subtype of bird flu previously detected only in animals.

This marks the initial instance of H5N5 being identified in a human, according to statements from both American and German health institutes. Prior to this case, the subtype had been observed in wild birds and poultry but had not been linked to human infections. The U.S. patient is an older adult with pre-existing medical conditions, currently receiving treatment in a hospital. Authorities reported that the individual kept domestic poultry, which had direct exposure to wild birds, suggesting a probable route of transmission.

Health officials, including the Centers for Disease Control and Prevention (CDC), have emphasized that the overall risk to the general population remains low. The CDC routinely tracks avian influenza cases in humans across the United States and notes that such infections are rare. To date, there have been 71 reported cases of avian influenza in humans in the U.S., with only one fatality recorded, although not all cases have been associated with the H5N5 subtype.

The Friedrich-Loeffler-Institute, Germany's leading research center for animal health, confirmed that no previous human cases of H5N5 infection have been documented globally. The institute also noted that the H5N5 subtype is less prevalent than the more widely recognized H5N1, which has caused widespread outbreaks among birds and sporadic infections in mammals since 2022. H5N5 has been present in wild bird populations, particularly in North America and Northern Europe, including Norway and Germany, but has not previously crossed the species barrier to humans.

Avian influenza, commonly referred to as bird flu, is a highly contagious viral disease that predominantly affects birds and can cause severe outbreaks in domestic poultry. The current global wave of bird flu, driven primarily by the H5N1 strain, has been the largest ever recorded, impacting multiple continents and resulting in significant losses within the poultry industry. While the H5N1 subtype is known to infect humans in rare cases, especially after close contact with infected birds, there have been no reported human cases of H5N1 in Germany, according to the Robert Koch Institute.

In response to the recent case, U.S. health authorities are conducting further investigations to determine the extent of exposure and to monitor for additional cases. Precautionary measures have been advised for individuals who come into contact with poultry, especially those with underlying health conditions. The CDC continues to recommend standard hygiene practices and the avoidance of direct exposure to sick or dead birds as effective preventive measures against avian influenza.

Experts maintain that, based on current evidence, the identification of H5N5 in a human does not represent a significant change in the overall public health situation. Surveillance and research efforts remain ongoing to better understand the transmission dynamics of avian influenza viruses and to mitigate potential risks to both animal and human health.