Surveillance of highly pathogenic avian influenza in wild mammals in Luxembourg for zoonotic risk prevention

Highly pathogenic avian influenza (HPAI) viruses have been repeatedly detected in wild birds in Europe for the past decade and are regularly transmitted to poultry upon direct or indirect contact. In Luxembourg, several occurrences of HPAI in domestic and wild birds have been detected over the past 2 decades of surveillance. Recently, the number of HPAI events in wild mammals has drastically increased in Europe and the Americas, especially in carnivores preying on sick or dead birds, mammals kept for fur production and sea mammals. Besides animal health and wildlife conservation issues, increased circulation of HPAI strains in mammals provides more opportunities for HPAI viruses to acquire specific mutations for adaptation, increasing the pandemic risk. Surveillance is thus crucial to identify and monitor emerging threats. In parallel with surveillance in birds, screening of wild carnivores was thus initiated in 2022 in Luxembourg, with more than 300 animals from all over the country tested since then. Red foxes, well represented in HPAI positive cases in Europe likely due to their preying behavior, constitute the main species tested in Luxembourg, followed by invasive raccoons. No HPAI virus has been detected so far in wild mammals in the country, despite occasional HPAI cases in wild and domestic birds during the 2021-2022 and 2022-2023 seasons. However, the situation is highly dynamic and requires continuous monitoring for both animal and public health.