Decline of Avian Flu in 13 European Countries, New Virus Affecting 12 U.S. States with 14 Human Infections

The latest reports show that the prevalence of Highly Pathogenic Avian Influenza (HPAI) in poultry and wild birds has declined in 13 European countries, a phenomenon not observed during the 2019-2020 epidemic season. However, the virus continues to circulate at low levels, making ongoing surveillance and control measures necessary. Most poultry infections are linked to indirect contact with wild birds, in line with previous observations. But there have also been cases of secondary transmission within poultry, indicating that the risk remains.

In the U.S., the situation has become more serious, with a new A(H5N1) virus genotype (B3.13) detected in over 130 dairy herds across 12 states. This strain has a particular affinity for dairy cattle, leading to high viral loads in the milk of infected cows and revealing a new potential transmission pathway. This highlights the evolving nature of highly pathogenic viruses and the urgency of adjusting control strategies to address this challenge.

Furthermore, the virus has now been detected in alpacas and walruses, expanding the range of host species and demonstrating the ability of highly pathogenic viruses to adapt and cross species barriers.

In human cases, 14 new human infections with avian influenza viruses were reported between March 13 and June 20, 2024, involving Vietnam, Australia, the U.S., China, India, and Mexico. Notably, Mexico reported a fatal case of the H5N2 subtype, the first human infection caused by this specific virus subtype. Most human cases were associated with exposure to poultry, live bird markets, or dairy cattle. While human infections with avian influenza viruses remain rare, there have been no sustained human-to-human transmission events to date.

Within the EU and EEA, the risk to the general public of contracting the currently circulating 2.3.4.4b clade A(H5) avian influenza viruses is considered low. However, for occupational groups and other specific populations with exposure to infected animals or contaminated environments, the risk remains low to moderate, highlighting the importance of targeted risk management for these vulnerable groups.