ETIDIOH - NEW

  Abstract Adding to the global burden of high pathogenicity avian influenza (HPAI) H5N1, an unprecedented five HPAI H7 outbreaks occurred globally in 2024 . Of these, three occurred in southeast Australia , with the independent emergence of HPAI H7N9, H7N8, and H7N3 , resulting in the destruction of 2 million poultry . Historical data demonstrates that H7 outbreaks in Australia do not occur randomly , rather, there is a strong association between the timing of the previous H7 outbreaks and rainfall patterns in southeastern Australia. We aimed to address a hypothesis wherein prior to H7 outbreaks in poultry, there was a detectable change in H7 prevalence and/or virus diversity in wild bird populations . We addressed this using virological and serological surveillance data generated from multiple programs. Despite the collection of thousands of samples, there was only weak evidence to support our hypothesis, which provides strong incentive to evaluate current surveillance approaches...

  Abstract Avian influenza A viruses pose ongoing threats to human and animal health, with H7 subtypes causing outbreaks globally . In Mexico , highly pathogenic H7N3 viruses have circulated in poultry since 2012, causing sporadic human infections . Here we analyzed genetic markers in hemagglutinin sequences from Mexican H7N3 isolates and conducted serological assays on human populations with poultry exposure . Our results show conserved avian-like receptor binding sites , thus limiting human adaptation , alongside antigenic drift and acquisition of glycosylation sites likely driven by vaccination. Serological testing of 1103 individuals revealed no detectable antibodies against H7N3, indicating a naïve population . Phylogenetic analyses revealed multiple virus clades circulating regionally. These findings suggest that while current H7N3 viruses have limited capacity for sustained human transmission, the lack of population immunity underscores the importance of continued surveillan...