New infections in animals should heighten concern of human H5N1.
With egg prices spiking due to bird flu, Agriculture Secretary Brooke Rollins announced steps last week to control the H5N1 virus, such as increasing financial relief for farmers with affected flocks and exploring vaccines and therapeutics for chickens. While these steps might help stabilize the egg supply in the short term, they’re insufficient for one simple reason: Chickens are not the only animals affected by this disease.
Three other species — cows, cats and rats — show why the Trump administration needs a more comprehensive strategy to protect the public.
Let’s start with cows, which have already been battling H5N1 for about a year. Nearly 980 dairy herds in 17 states have been affected. Stacey Schultz-Cherry, an influenza expert at St. Jude’s Children’s Research Hospital, told me scientists were “quite shocked” when the spillover first happened from birds to cows. Many thought it would be a one-off event, with subsequent transmissions of that strain of bird flu, called B3.13, happening among cows themselves.
Now, it appears the cross-species spillover has occurred at least two more times. Another strain of the virus — D1.1, which has been spreading among poultry — was identified in dairy herds in Nevada and Arizona this month. This means even if transmission among cows were curbed, they could continue to get sick from birds.
Moreover, the D1.1 strain is concerning because it was found in two people who fell severely ill during this outbreak. One person, a teenager, required intensive care for multi-organ failure; the other died.It’s not known whether this strain causes more severe disease in humans, but its detection in cows should increase urgency to test dairy workers.
Cats, too, have long been susceptible to H5N1 infection. In past outbreaks, they contracted the virus primarily from eating dead and dying birds. In this one, they also appear to have contracted H5N1 through contaminated raw milk and raw pet food.
Last month, the Centers for Disease Control and Prevention published a report suggesting that two dairy workers in Michigan transmitted bird flu to their pet cats. Both were indoor cats that did not consume raw milk or food. One developed lethargy, an unsteady gait and other neurological symptoms. After four days, it needed to be euthanized. The other cat, which lived in a separate household, developed neurological symptoms and died within a day. Both tested positive for bird flu postmortem.
In both cases, the owners had occupational exposures to the virus and reported symptoms that preceded their cats’ illnesses. Because both declined testing, scientists cannot definitively say that the cats contracted the virus from the workers, but it seems likely.
If cats could contract H5N1 from humans, could the reverse be true, too? This has been documented in the past, said Kristen K. Coleman, a professor at the University of Maryland School of Public Health. She cited a 2004 bird flu outbreak in a Thailand tiger breeding facility in which human workers contracted the virus. A spillover from cats to humans “could spark a human pandemic,” she said.
Finally, the rats. In late January, the Agriculture Department added the black rat to the list of mammals known to have bird flu. Coleman says this species heightens her unease because it is smaller and cats “frequently and readily prey on” it. If cats eat infected rats, they could get H5N1 and spread it to one another and to other species. The black rat’s mobility between farm and urban areas could also speed up the virus’s already high rate of species spillover.
Meghan Frost Davis, a veterinarian and Johns Hopkins professor, has been warning for months that rodents contracting H5N1 would be a major red flag in the evolution of bird flu. “What we really need to understand is to what degree rodents are involved,” she said, so that containment can be more targeted and more precise. She also urges better surveillance and data reporting of companion animal infections and more education of veterinary workers so that they are looking for bird flu across species and aware of their own risk.
Every expert I spoke to for this column — and indeed for every piece I’ve written on bird flu — emphasized the urgent need for rapid, accessible testing. As Schultz-Cherry said, “We need to find ways to test anybody and everybody that has a potential occupational exposure — and their households.” Clinicians treating high-risk workers should have rapid antigen tests, as should veterinarians.
Thus far, 70 people have tested positive for H5N1. Americans need to be ready for when that number multiplies. The Biden administration had taken steps to expedite vaccine development, including by investing $590 million in Moderna’s mRNA technology for a bird flu vaccine. The Trump administration has said it might withdraw this funding.
Doing so would be a profound mistake. As bird flu affects more and more species, containment efforts alone will not be enough. The administration must also prepare for H5N1 potentially becoming a significant threat to human health.
This article is from WWSG thought leader, Leana Wen.
