The Current Bird Flu Outbreak Is the Deadliest, Most Persistent in U.S. History

Analysis by Caitlin Welsh, Zane Swanson, and Joely Virzi

Published April 30, 2025

The current bird flu outbreak has become the longest and deadliest animal disease emergency in U.S. history, with devastating losses to poultry flocks nationwide and major implications for U.S. agriculture and food security.

1. In just over three years since its detection in 2022, H5N1 bird flu has affected over 168 million birds across all 50 states and Puerto Rico. By 2023, the U.S. Department of Agriculture (USDA) Animal and Plant Health Information Service (APHIS) had declaredthe current outbreak to be the "largest and longest outbreak in the history of the United States." By comparison, the previous record-breaking 2014-15 outbreak of bird flu lasted less than seven months, affected 50.5 million birds, and did not spilloverinto dairy cattle.
2. The unprecedented scale and duration of the infections raises serious concerns for U.S. agriculture and food security. The current H5N1 outbreak has contributed to a reduction in egg-layer flocks and the subsequent supply of eggs-driving egg prices sharply upward-an indicator of potential vulnerability for food-insecure populations. In March 2025, retail prices were 60.4 percent higher than in March 2024.
3. Since unveiling an updated strategy to combat bird flu in February 2025, the USDA has made some progress in curbing the outbreak, protecting the U.S. poultry industry, and lowering egg prices. Still, the USDA has received bipartisan criticism for focusing uniquely on poultry and overlooking other affected bird species and dairy cattle. To date, more than 1,000 U.S. dairy herds have been affected. Additionally, termination of U.S. fundingfor efforts to stem H5N1 bird flu in other countries, including for the UN Food and Agriculture Organization's Global Health Security Program, could undermine domestic containment efforts.

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