The Centers for Disease Control and Prevention (CDC) has confirmed a human case of avian influenza A(H5N1) in California, but the risk to the general public remains low. The virus was sequenced from a pediatric patient’s nasopharyngeal specimen and showed similarities with viruses detected in dairy cattle and poultry in the US.
The initial analysis suggested the virus was part of the clade 2.3.4.4b family, similar to outbreaks in dairy cattle and poultry. However, further sequencing revealed it shared close nucleotide identity with recent B3.13 viruses detected in California. Epidemiologic investigations did not identify a possible source of exposure.
The CDC also assessed the virus for potential changes that could impact its infectivity or transmissibility in humans. The findings indicate the virus retains avian receptor binding properties and lacks mutations associated with reduced susceptibility to antivirals.
This case highlights the importance of a collaborative approach to responding to outbreaks, including virologic risk assessments based on genetic data. While sporadic human infections are not uncommon during H5N1 outbreaks, the immediate risk to the general public remains low. Public health surveillance and investigations will continue to monitor for concerning changes in the epidemiology of human cases.
Source: https://www.cdc.gov/bird-flu/spotlights/h5n1-response-12092024.html