A Washington resident has contracted a unique strain of bird flu, marking the first U.S. human case of this type since February. Health officials in Washington state confirmed the diagnosis on Friday, revealing that the patient, an older adult with underlying health conditions, is hospitalized. The resident was infected with the H5N5 bird flu virus, which appears to be a novel strain not previously seen in human cases. This discovery is significant as it could indicate a shift in the virus's behavior or transmission patterns. While the H5N5 strain is not considered a greater threat to human health compared to the H5N1 virus, which caused 70 reported human infections in 2024 and 2025, it highlights the ongoing need for vigilance and monitoring in bird flu prevention and management. The Centers for Disease Control and Prevention (CDC) has issued a statement reassuring the public that there is no increased risk to public health, but they are awaiting further testing on a specimen from Washington to confirm the findings. The distinction between H5N5 and H5N1 lies in the proteins involved in the virus's release and spread, with the former potentially having a different preference for infecting birds. The resident, who has not been identified, kept a backyard flock of domestic poultry that had been exposed to wild birds, suggesting that the source of infection may be either the domestic poultry or the wild birds. This case underscores the importance of continued research and surveillance to understand the evolving nature of bird flu viruses and their potential impact on human health.
