What happened?

The H5N1 bird flu outbreak in the United States has grown since it arrived in early 2022. The virus has infected more than 208 million poultry, over 19,000 wild birds, and cattle herds in 20 states, according to the nonpartisan research arm of Congress called the Congressional Research Service (CRS). The report was updated this month.

California has been hit hardest among cattle-raising states, accounting for 773 of the 1,168 confirmed herd infections nationwide. Scientists believe the strain infecting cattle spread from birds to cows earlier than originally detected.

Why Does it Matter to Me?

When poultry flocks are infected, they are typically destroyed to stop the spread. More than 208 million birds lost over four years means fewer eggs and chickens reaching grocery shelves, which pushes prices up for everyday shoppers.

The virus currently does not spread easily between people. But the CRS report notes that a recent case in Louisiana showed the virus can pick up genetic changes inside an infected patient, which scientists say could give it a greater ability to infect humans over time.

Wild birds carry the virus along migration routes, meaning the outbreak is not contained to farms. Cattle herds, domestic flocks, and wildlife remain active sources of spread.

Both sides, now

The Trump administration announced a five-part response plan in February 2025, backed by $1 billion in federal money. The plan commits up to $500 million to biosecurity measures on farms and up to $400 million to help farmers restock their flocks. It also reduces some rules on the chicken and egg industry and explores vaccines and other treatments for egg-laying poultry.

Supporters of the approach say investing in farm-level prevention and flock recovery addresses both the agricultural and economic damage. Some scientists and members of Congress, however, have raised concerns that the virus is spreading faster than current tracking systems can detect, and that the shift away from traditional culling-focused responses may leave gaps.

Sixteen U.S. senators wrote to the Agriculture secretary in May 2024 urging stronger federal coordination on pathogen tracking and clearer communication with farmers. Congress has also introduced bills to expand monitoring: one bill, H.R. 766, would authorize a national wastewater tracking system to watch for H5N1 and similar viruses, and H.R. 2868 would make highly pathogenic avian influenza (HPAI) a high-priority research area for the Agriculture Department.

What happens next?

Neither bill has been signed into law. Both would need to pass the full House and Senate before reaching the president's desk, and no votes are currently scheduled.

The U.S. Department of Agriculture (USDA) conducted more than 4,300 farm biosecurity assessments between January 2025 and late July 2026. The Centers for Disease Control and Prevention (CDC) continues to monitor human cases and test wastewater for the virus. The National Institutes of Health set a research agenda in December 2024 focused on the dairy outbreak and how easily the virus could pass between people.

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