This year, herds across the U.S. were infected with avian influenza.
Suzanne Kreiter/Boston Globe via Getty Images
A highly contagious type of avian influenza began spreading among dairy cows across the United States earlier this year, providing one of the best opportunities ever for the pathogen to evolve and become more susceptible to infecting people.
Infectious disease experts have been concerned about a virus called H5N1 for decades. Since 2003, more than 900 people are known to have been infected worldwide, and about half of them have died.
Article modified on December 11, 2024
This article has been modified to correct the recovery status of people with known infectious diseases.
