Why It Matters

Federal agencies and Congress are grappling with an expanding H5N1 outbreak that has infected more than 19,000 wild birds, over 208 million poultry, and 1,168 cattle herds across the U.S. since 2022. A Congressional Research Service (CRS) report titled "Avian Influenza (Bird Flu) in the United States," updated in September, examines the scope of the crisis and the Trump administration's response, laying bare tensions between agricultural stabilization and public health preparedness. Some Members of Congress have expressed concerns about the spread of H5N1 and its potential health effects on humans, as well as its possible negative economic impact on agriculture, especially in the poultry and livestock industries.

The Big Picture

H5N1 has spread worldwide since a 2021 outbreak in Europe reached the U.S. in early 2022. Migratory pathways can be conduits for the spread of avian influenza to mammals including humans from wild birds. Since March 2024, the virus has infected cattle herds in 20 states, concentrated heavily in California, where 773 of 1,168 confirmed cases occurred. The genotype infecting cattle is believed to have originated from an earlier bird-to-cow transmission event than initially detected.

Current strains do not spread readily from person to person. A recent case in Louisiana showed that genetic changes can emerge within an infected patient, suggesting the virus may acquire enhanced ability to infect humans during replication.

The USDA announced its Five-Pronged Approach in February 2025, committing $1 billion to the effort, including up to $500 million to biosecurity measures and up to $400 million in aid for flock repopulation. The approach includes reducing regulatory requirements on the chicken and egg industry to stimulate innovation and reduce prices, and exploring pathways toward vaccines, therapeutics, and other strategies for protecting egg-laying poultry.

Between January 20, 2025, and July 23, 2026, USDA conducted 4,324 wildlife and domestic biosecurity assessments on U.S. poultry farms. The CDC monitors human cases of H5N1, receives reports from public health laboratories, performs tests in wastewater for the prevalence of H5N1, and provides guidance to state health departments on how to investigate suspected cases. The National Institutes of Health, through its National Institute of Allergy and Infectious Diseases, established a research agenda in December 2024 focused on the dairy outbreak and human-transmission potential.

Congress has introduced bills addressing surveillance and research. H.R. 766 would authorize the National Wastewater Surveillance System to monitor avian influenza and other zoonotic pathogens. H.R. 2868 in the 119th Congress would designate HPAI study as a high-priority research and extension area under specified U.S. Code provisions for the Secretary of Agriculture. In May 2024, 16 U.S. Senators urged the Secretary of Agriculture to strengthen federal coordination on pathogen surveillance and farmer communication.

The Bottom Line

The Trump administration's shift toward biosecurity investment and reduced culling represents a departure from traditional stamping-out approaches, though scientists caution that the virus's capacity to adapt and mutate may outpace current surveillance and response capabilities. Federal agencies operating under a One Health framework released in January 2025 face an unresolved tension: whether the current policy mix can contain a pathogen spreading faster than detection systems can track, particularly as H5N1 continues circulating among wild birds, livestock, and domestic poultry.

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