The IDWG corner: Highly Pathogenic Avian Influenza (HPAI) in European Wild Mammals: a silent threat?

The infectious disease corner:

Highly Pathogenic Avian Influenza (HPAI) in European Wild Mammals: a silent threat ? During our recent pre-Christmas EAZWV webinar, our colleague Carlos Sacristan highlighted the evolving threat posed by the current HPAI H5N1 strain, which is no longer confined to avian species and now poses significant risks to mammalian populations. The recent list published by EFSA reveals now more than 60 mammals species with at least one viral detection of the H5N1 (or H5Nx) clade 2.3.4.4b strain. The geographic and species range of infections is expanding rapidly, with ongoing outbreaks increasingly reported in marine mammals, terrestrial carnivores, and now, ungulates;  infection and concerns surrounding domestic cattle milk have made headlines, and now recent evidence points to risks in equine species : in the forthcoming issue of the CDC journal Emerging Infectious Disease of January 2025, a new paper is demonstrating how Mongolian  horses show evidence of H5N1 seroconversion, while they’re also routinely harboring H3N8 equine influenza virus…

Zoos are not spared, with several cases already reported notably among carnivores in Southeast Asia (big cats) and Europe, including species such as bush dogs and American black bear. Consequently, HPAI should be now considered a key differential diagnosis for acute fatalities and cases exhibiting neurological or respiratory symptoms in exotic mammals. It is also imperative to incorporate HPAI into the Disease Surveillance Plan for zoo mammals. To mitigate associated risks, efforts must be made to reduce interactions between zoo mammals and local waterfowl, particularly in relation to heavily frequented ponds, as well as wanted / unwanted predation.

Additionally, implementing serological monitoring in high-risk enclosures may enable early detection of viral co-circulation or subclinical infections, or at least confirm their absence. Do not hesitate to question the Infectious Disease Working Group about those subjects.