With H5N1 avian influenza causing unprecedented outbreaks in mammals around the world — including U.S. dairy cattle — infectious disease experts are raising concerns that the U.S. isn’t doing enough to get ahead of any potential problems.
“We really need to be moving quickly to get our heads around what’s happening in the animal population and also what’s happening in the human population,” James Lawler, MD, MPH, of the University of Nebraska Medical Center’s Global Center for Health Security, told MedPage Today. “I don’t think we’ve been testing adequately to be able to get a real picture of that.”
Lawler said we should be particularly cautious “when a virus starts doing things that we don’t expect it to do, like circulating widely in a species where we normally haven’t seen infections. We really need to respect the potential danger that exists.”
Federal officials have confirmed that 33 dairy cattle herds in eight U.S. states have tested positive for H5N1.
However, the outbreak is likely much larger than that, and has probably been spreading undetected for much longer than thought, Lawler said. That’s evidenced by the fact that FDA detected H5N1 in samples from the commercial milk supply, and by recently released viral sequences from animal infections supplied by the U.S. Department of Agriculture (USDA), from which virologists concluded the outbreak likely began in December 2023, with a single spillover incident from birds into cows.