NIH A highly pathogenic avian influenza (HPAI) H5N1 outbreak in U.S. dairy cattle began in early 2024. As of early November, infections have been confirmed in hundreds of cattle in 15 states. More than 40 human cases have also been reported. Most of the human cases were in farm workers who had mild respiratory symptoms or conjunctivitis (“pink eye”). The CDC currently considers the public to be at low risk.
A research team led by Dr. Yoshihiro Kawaoka at the University of Wisconsin-Madison previously studied an HPAI H5N1 virus found in the milk of an infected cow. That virus could infect mice and ferrets but didn’t spread efficiently through the air. The team recently did a similar study of a virus from one of the infected farm workers. Results from the study, which was funded in part by NIH, appeared in Nature on October 28, 2024.
The scientists found that the virus infected and replicated efficiently in cultured human lung cells. It could also infect cultured cells from the human cornea, albeit less efficiently than in lung cells.