The mammary glands of domesticated livestock and humans could potentially harbor avian influenza, posing a significant concern for public health and animal welfare. An ongoing outbreak of highly pathogenic avian influenza has affected over 184 million domestic poultry and more than 1,000 dairy cow herds since 2022. A recent study led by Iowa State University researchers reveals that the mammary glands of pigs, sheep, goats, beef cattle, and alpacas are biologically suitable for harboring avian influenza due to high levels of sialic acids. This finding raises the question of whether there is potential for transmission among these animals and humans. Sialic acid, a sugar molecule found on the surface of animal cells, acts as a docking station for the influenza virus, enabling it to infect host cells. A previous study by the same researchers found that dairy cattle udders have high levels of sialic acid, explaining the rapid spread of the H5N1 avian influenza outbreak among dairy herds. The study, published in the Journal of Dairy Science, also identified the same receptors in the mammary glands of humans. While only a few sporadic cases of H5N1 infection have been reported in the examined animals, widespread testing is not conducted, according to Dr. Todd Bell. The presence of the virus in milk from infected cows has likely contributed to the spread of H5N1 and increases the risk of transmission to humans. The study highlights the potential for both avian and seasonal influenza viruses to come into contact and transmit between different species, raising concerns about the emergence of more dangerous adaptations. The researchers emphasize the need to stay ahead of the virus to prevent further replication and potential evolution into a more troublesome form.
