Seroprevalence of HPAI H5Nx in domestic cats: assessing cross-species transmission risk

The circulation of clade 2.3.4.4b high pathogenicity avian influenza viruses (HPAIV) H5Nx has intensified these past few years, fueling widespread epizootics and increasing mammalian exposure through direct or indirect contact with infected birds. Domestic cats occupy a unique position in avian influenza virus epidemiology, as their predatory behavior places them at the interface between wild and domestic environments, which makes them a key species for studying cross-species transmission of avian influenza viruses. In this ongoing study, we analyzed sera from 462 domestic cats (≥1-year-old) with outdoor access, sampled from across mainland France. Initial screening with a commercial anti-H5 ELISA identified seropositive samples, which were subsequently confirmed using an indirect haemagglutination test. Preliminary findings revealed a total of 11 positive samples and a seroprevalence of 1.64% (CI 0.4-3.82%). Further analyses aim to identify risk factors, including outdoor exposure duration, hunting behavior frequency, proximity to poultry farms, and regional distribution. We plan to reach 700 serums over the next few months. This is the first large-scale seroprevalence study of avian influenza in domestic cats in France. The findings will enhance our understanding of feline exposure to clade 2.3.4.4b H5Nx viruses, a determinant step in assessing the role of cats as vessel for the emergence of mammal-adapted strains.

Pierre Bessière (1), Jessie Brun (2), Amélie Marchand (2), Marie-Christine Cadiergues (2), Jean-Luc Guérin (1) (1) IHAP, Université de Toulouse, INRAE, ENVT, Toulouse, France (2) Small Animal Clinic, Université de Toulouse, ENVT, Toulouse, France

Avian influenza in mammals, pandemic preparedness, and one health