The United States has confirmed its first human fatality linked to the H5N5 bird flu strain, marking a critical moment in the ongoing monitoring of public health threats. The individual, an older adult with pre-existing health issues, was hospitalized in early November after displaying flu-like symptoms, including respiratory difficulties and high fever. Laboratory analysis from the University of Washington subsequently identified the H5N5 subtype, a finding corroborated by the Centers for Disease Control and Prevention (CDC). This incident represents the first acknowledged human case of H5N5 globally.
Recent studies led by researchers from major universities reveal alarming findings regarding the resilience of avian influenza viruses like H5N5. Unlike typical human flu viruses, which are affected by elevated body temperatures, H5N5 and similar strains can survive and replicate even at these higher temperatures, which are part of the body's natural defense reaction during a fever. Experiments utilizing animal models demonstrate that while human influenza viruses are significantly weakened in such conditions, avian strains remain robust, a trait linked to a specific gene variant known as the 'temperature-sensitivity gene.' The implications of this resilience may partially explain the severe health risks associated with bird flu, particularly when the virus infects areas of the lungs that align with fever conditions.
Health officials indicate that, despite this unfortunate event, the immediate risk to the general population remains low at this time. There has been no evidence of human-to-human transmission associated with this case. Close contacts of the infected individual, as well as those connected to their bird flock, are being closely monitored for any symptoms. Experts emphasize that this occurrence serves as a crucial reminder of the potential for avian flu viruses to mutate and infect humans. Continuous surveillance of wildlife, domestic birds, and backyard poultry flocks is essential to facilitate early detection and to prevent possible outbreaks in the future.
Distinctively, H5N5 is categorized as an avian-origin influenza virus predominantly affecting birds. Its high pathogenic nature, similar to the more widely known H5N1 strain, poses significant dangers to avian populations and raises alarms regarding rare transmissions to humans. The unusual ability of avian flu viruses like H5N5 to withstand high body temperatures distinguishes them from common flu strains, complicating the body's natural immune response and heightening the risk of severe illness during infection.