When a strain of bird flu sweeps through factory farms, where birds are tightly confined, the current “solution” involves immense cruelty.

This is why it’s a genuine milestone in the fight against factory farming that the Humane Society of the United States, Farm Sanctuary and Mercy For Animals just settled a lawsuit against the U.S. Department of Agriculture over its reckless response plan for outbreaks of Highly Pathogenic Avian Influenza.

Factory farms (where virtually all meat, eggs and dairy now come from) are breeding grounds for disease. By packing thousands of stressed animals into cages or sheds, factory farms provide viruses and other pathogens with the perfect conditions to spread and mutate into more dangerous and contagious strains, a process known as amplification. State laws that prohibit cruel, tight confinement like California’s Proposition 12 have an important role to play here, but factory-farming interests are seeking to strip states of their ability to pass such laws. More on that below.

In a bird flu outbreak, the current USDA approach involves killing every animal at or near the impacted facility. Often this is done by an exceptionally cruel method called “ventilation shutdown,” which means shutting off a facility’s ventilation system and slowly suffocating conscious birds to death. The government then uses taxpayer dollars to reimburse producers for the cost of restocking their operations with new animals.

In 2015, the HSUS proposed a better way: that the agency should require producers re-stocking their facilities after an outbreak to shift to cage-free or other systems that give birds more space and the ability to engage in healthy, natural behaviors. But the USDA decided to stick to an approach that incentivizes re-stocking factory farms with dangerously high numbers of animals, often confined to the point of virtual immobilization.

Our lawsuit alleged that the agency’s plan inadequately analyzed how killing and burying or burning millions of tightly confined birds threatens wildlife, habitats, water supplies, air quality and human health. The settlement requires the agency to revisit these issues and conduct a more in-depth analysis of these threats. This is an important and timely development, as currently the U.S. is in the midst of another nationwide bird flu outbreak that has quickly spread to 40 states.

Though the USDA agreed that overcrowding animals can amplify influenza, instead of doing anything to discourage it, the agency said that it planned to just “encourage farmers to consider reducing the number of birds in poultry houses as part their best management practices.” Unfortunately, there’s no evidence that this supposed encouragement led to any reduction in cruel and dangerous confinement anywhere, and now six years later the U.S. is enduring of another devastating bird flu outbreak.

But thanks to the settlement, the USDA will go back to the drawing board, and nothing is stopping the agency from adopting the anti-confinement incentives the HSUS suggested in 2015. The agency never questioned the efficacy of those incentives; it rejected them without examining whether they may prove effective in limiting the threat of bird flu.

This case overlaps with a major legal battle in which the HSUS is currently engaged. We’re defending California’s landmark Proposition 12 in front of the U.S. Supreme Court. The HSUS led the campaign that passed Proposition 12 in 2018, banning the extreme confinement of mother pigs, egg-laying hens and calves used for veal, while prohibiting the sale of pork, eggs and veal from factory farms that cruelly confine animals. Instead of complying with this commonsense and hugely popular reform, the pork industry is trying to get the law overturned.

It's obvious to most people that the pork industry’s practice of locking a mother pig in a barren metal cage so tightly that she can’t turn around is cruel. But these cages (known as “gestation crates”) also pose an enormous threat to public health. Confining mother pigs in gestation crates stresses the animals and this suppresses their immune responses. In pig breeding facilities, hundreds or thousands of pigs are confined right next to each other in these crates, helping influenza and other pathogens spread more easily. Just like overcrowding birds, overcrowding pigs risks amplifying influenza, increasing the likelihood of generating a virus that could become the next devastating human pandemic. This is not hypothetical: The 2009 swine flu pandemic jumped from pigs to humans and killed hundreds of thousands of people worldwide.

Factory farms that force animals to live in overcrowded, filthy conditions are a massive threat to public health, in addition to being our nation’s largest source of animal suffering. The HSUS will continue to battle intensive farm animal confinement wherever the fight takes us—whether it be in courts, corporate boardrooms, online or the public square. You can join us by adding your name to this action alert.

The bird flu lawsuit was prepared and defended by pro bono counsel at the law firm Shearman & Sterling, LLP and the HSUS’s Animal Protection Law team along with co-plaintiffs, Mercy For Animals and Farm Sanctuary.

Sara Amundson is president of the Humane Society Legislative Fund.