Limited susceptibility and transmission of H5N1 clade 2.3.4.4b HPAI virus in pigeons
Avian influenza viruses (AIVs), particularly highly pathogenic avian influenza virus (HPAIV) strains such as H5N1 clade 2.3.4.4b, have caused significant outbreaks in wild and domestic bird populations worldwide, with occasional zoonotic spillover events. Columbiformes (pigeons and doves) frequently inhabit environments in close proximity to poultry farms and humans; however, their role in HPAIV epidemiology remains poorly defined.
A study conducted by UK scientists investigated the susceptibility of domestic pigeons (Columba livia) to clade 2.3.4.4b H5N1 HPAIV, focusing on infection dynamics, viral shedding, and the potential for transmission to naive pigeons and chickens.
Using decreasing doses of an H5N1-AB virus (genotype AB), representative of strains circulating in the UK and Europe between 2021 and 2023, pigeons were experimentally infected to determine the median infectious dose (MID₅₀), clinical manifestations, shedding profiles, and transmission capability. Across all dose groups, pigeons exhibited no clinical signs. Only the highest dose group demonstrated low-level viral RNA shedding and seroconversion, with an estimated MID₅₀ of 10⁵ EID₅₀. Viral RNA was detected at minimal levels in tissues, with no notable pathological changes. Crucially, no transmission occurred between pigeons or from pigeons to chickens housed in direct contact. Environmental contamination was also negligible.
These findings, consistent with previous studies, indicate that pigeons exhibit low susceptibility to infection and limited potential for onward transmission of this HPAIV clade.
