The United States recently confirmed its first case of the rare avian influenza strain H5N9, causing concern among experts who fear the virus is mutating. The strain was discovered on a duck meat farm in California in November 2024, leading to the quarantine and subsequent culling of all 119,000 birds on the farm. This finding comes amidst the ongoing bird flu outbreak that has already claimed the lives of over 145 million birds since 2022.
The H5N9 strain, first identified in China a decade ago, is a genetic combination of other strains such as H5N1, H7N9, and H9N2. Public health experts warn that the detection of H5N9 in the U.S. could potentially lead to the emergence of unpredictable new viruses that may impact both animals and humans. Virologist Angela Rasmussen emphasized the potential threat, stating that reassortment of viruses can lead to pandemics.
The N9 gene in the rare strain is derived from the subtype H7N9, which has caused several human and poultry outbreaks in China, resulting in significant fatalities. Although there is limited research on the impact of H5N9 on humans and animals, clinical signs on the California farm included increased mortality rates. While the virus has shown low mortality rates in mice, the potential for human infections and pandemic subtype remains uncertain.
Surveillance and monitoring of avian viruses, particularly in ducks, are crucial to prevent further reassortment and potential threats to public health. The recent spread of bird flu to cows in 2024 has further exacerbated the situation, with more than 17 million birds affected in the last 30 days and 66 commercial flocks reporting outbreaks. Farmers have been forced to depopulate flocks to contain the spread, leading to supply shocks and increased egg prices, which have become a contentious issue in the broader debate on inflation.
In light of these developments, it is essential to prioritize surveillance and control measures to prevent the spread of avian influenza and mitigate the risks posed by emerging strains like H5N9. Public health authorities, agricultural agencies, and researchers must work together to address the evolving threat of bird flu and safeguard both animal and human populations from potential pandemics.
