Recent Insights into Highly Pathogenic Avian Influenza-Recent Insights into Highly Pathogenic Avian Influenza

Video Transcription

Video Summary

The webinar focused on the recent spread of highly pathogenic avian influenza (HPAI) H5N1 into U.S. dairy cattle and the One Health response to this emerging threat. Dr. Todd Bell of Iowa State University described how the outbreak was first confirmed in Texas and Kansas in March 2024 and has since spread to hundreds of herds across multiple states. He explained the One Health framework, emphasizing the connection between animal health, human health, and environmental health, and highlighted the rapid collaboration among state, federal, and academic laboratories to diagnose and investigate the outbreak.<br /><br />Dr. Bell’s team studied why H5N1 was appearing in milk and mammary tissue. They found the virus in epithelial cells of the mammary gland and showed that both avian-type and mammalian-type influenza receptors are present there, helping explain why the virus can infect cattle and produce high viral loads in milk. He noted that this virus does not behave like classic respiratory influenza and may spread in dairy settings through milking equipment and human handling rather than primarily by respiratory transmission.<br /><br />Dr. Juergen Richt of Kansas State University presented experimental infection studies in calves and lactating cows. Calves showed mild respiratory infection with no transmission to sentinel animals. In lactating cows, however, intramammary inoculation caused severe mastitis, dramatic drops in milk production, high viral shedding in milk, and significant illness. His results supported the idea that the udder is a major site of replication and that contaminated milking procedures likely play a central role in spread.<br /><br />Both speakers stressed the need for ongoing surveillance, sequencing, and cross-sector collaboration to track viral changes and prevent future outbreaks.

Keywords

HPAI H5N1

avian influenza

dairy cattle

One Health

mammary gland

milk contamination

mastitis

viral shedding

surveillance sequencing

cross-sector collaboration