One confirmed and one potential human case of influenza A(H5N1) detected through an expanded subtyping protocol

December 10, 2025
Clinical Microbiology
Grant P. Higerd-Rusli, Abraar Karan, Seth A. Hoffman, Ingrid E. A. Morante, ChunHong Huang, Malaya K. Sahoo, Matthew M. Hernandez, Benjamin A. Pinsky
Pathogen:influenza A(H5N1)
Infection Type:Respiratory infection
Pathogen Type:Virus

Case Summary

This report details one confirmed and one potential human case of influenza A(H5N1) detected through an expanded subtyping protocol. The confirmed case involved a patient presenting with respiratory symptoms, where H5N1 was identified via PCR and sequencing. The second case, a healthcare worker, showed serological evidence of exposure without clear symptoms. Current surveillance often misses community-acquired infections by focusing only on those with known animal exposure. Implementing universal H5 subtyping on all influenza A-positive samples allowed for broader detection. Teaching point: Expanded laboratory surveillance beyond animal exposure criteria is crucial for early detection of novel zoonotic influenza strains and understanding community transmission.

DOI: 10.1128/asmcr.00165-25