During 1–3 July 2024 we assessed the detection of the NSW H7N8 HPAI virus by twelve diagnostic assays used by NSW Health Pathology (NSWHP) laboratories. We subsequently also reviewed the 12–25 November 2024 data from the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Emerging Biological Threats survey, assessing the detection of five other avian influenza viruses: H5N1, H7N3, H7N9, H9N2, and H10N7. These assessments were needed because knowledge of the ability to detect avian influenza virus on human diagnostic platforms is critical for minimising public anxiety in the event of human infections, and facilitates public health response planning.
The New South Wales H7N8 avian influenza virus was diluted in viral transport medium (Tréidlia Biovet) and distributed at 4°C for blind testing in NSWHP laboratories. The H5N1, H7N3, H7N9, H9N2 and H10N7 viruses were de‐identified and distributed through the RCPAQAP external quality assessment programs (EQAP) as diluted RNA from cultured virus. The diagnostic tests used were standard commercial molecular test kits for human respiratory viruses and a specialised influenza hemagglutinin (H)‐subtyping test. Human research ethics approval was not sought for this study, as human samples were not used.
The NSW avian influenza H7N8 virus was detected as influenza A virus by all twelve assessed diagnostic assays used by NSWHP laboratories. The H5N1, H7N3, H7N9, H9N2, and H10N7 viruses were each detected as influenza A viruses by all RCPAQAP EQAP 2024 survey test results. The RCPAQAP EQAP survey reports for Molecular Respiratory Pathogens and Molecular Rapid Diagnostics indicated that the diagnostic tests we assessed were representative of tests routinely used for the molecular detection of influenza A in Australia, New Zealand, and South Pacific nations, corresponding to 392 of 425 results submitted.
We found that the probability of avian influenza virus being detected by human diagnostic testing platforms used in Australia and the region is extremely high. The 100% detection rate for all six avian influenza A viruses assessed alleviates concerns arising from the unstated information about PCR target sequences in commercial diagnostic test instructions‐for‐use documents. Our findings indicate that current human pathology respiratory virus diagnostic tests can reliably detect the H5, H7, H9, and H10 avian influenza virus strains as influenza A virus, including the HPAI strains involved in the 2024 Australian outbreaks and avian influenza A viruses detected during 2010–2022.
Our findings raise some topics for consideration. First, assessing the ability to detect new avian influenza A viruses depends critically on access to outbreak virus and well defined, pre‐arranged agreements between jurisdictions to share virus. Access to virus from early in an outbreak is highly important because, although synthetic nucleic acid‐positive control reagents are helpful, it is prudent to test the detection of new virus strains on human diagnostic platforms, especially viruses that have evolved in non‐human animal hosts (eg, the H5, H7, and H9 viruses). Second, identifying avian viruses as influenza A viruses is required before subtyping is undertaken, if required; for example, for people exposed to avian viruses, including those in the households of HPAI‐exposed workers, or during periods of suspected human‐to‐human transmission. Molecular confirmation as influenza A virus also permits forwarding samples for sequencing, and data sharing ensures the ongoing suitability of assays and mapping of viral evolution. Third, accurate detection in Australia and the region of infrequent avian influenza infection in humans increases community confidence in public health responses and informs decisions about workforce management and the strategic use of test supplies. In our study, the levels of avian influenza in human respiratory samples was not assessed, but viral loads in people with symptomatic infections are generally sufficient for detection by PCR testing.
Our findings support public confidence that respiratory virus PCR tests can detect avian influenza in humans, in Australia, New Zealand, and South Pacific nations and highlight the benefits of collaboration between human and animal health authorities for detecting animal viruses that are rarely targets in human pathology testing.