Bird flu’s global footprint is widening as fall migration begins. Wisconsin faces its largest cull in years with 3 million hens destroyed, while South Dakota’s death toll has surpassed 400,000 turkeys and Minnesota is back under outbreak response after months of reprieve. Nebraska confirmed its first-ever case in dairy cattle, ending a summer lull in livestock detections. New farm outbreaks in Montana, South Korea, and Taiwan highlight the virus’s seasonal spread along flyways, while Poland and Brazil’s poultry sectors are grappling with trade disruptions. Together, these developments signal both the persistence of H5N1 and the mounting economic toll across continents.
Wisconsin to Cull 3 Million Birds After H5N1 Detected in Jefferson County
A commercial poultry farm in Jefferson County, Wisconsin, will cull 3 million egg-laying hens after testing confirmed H5N1, according to the state agriculture department. The site, operated by Daybreak Foods, is under quarantine while state and federal officials oversee depopulation and disposal through composting. This marks Wisconsin’s first detection since April and the farm’s second outbreak, with a prior case reported in 2022 under different ownership. Officials said there is no threat to the food supply, and workers are being monitored for infection (Kaeding, 2025).
Recent South Dakota Death Toll Reaches 419,650 Turkeys
The South Dakota death toll from H5N1 has reached 419,650 turkeys following detections in eight commercial flocks and one backyard flock over the past month, according to USDA-APHIS. State veterinarian Beth Thompson said blue-winged teal have been identified as carriers of this season’s virus, noting that teal are among the earliest migratory waterfowl and may explain South Dakota’s early surge. The State Department of Health emphasized that the risk to the public remains low but advised hunters to follow CDC guidance when handling wild birds (Haiar, 2025).
Minnesota’s Battle With Bird Flu Resumes
Minnesota has confirmed its first H5N1 detection in poultry since April, involving a commercial turkey flock of 20,000 birds in Redwood County. In a statement, the Minnesota Board of Animal Health noted that officials and industry had worked through the summer to clear quarantined sites, allowing the state to declare freedom from avian influenza on August 25. The new detection, however, resets the state’s response measures and brings disease teams back into action as fall migration begins. Officials added that the finding is not unexpected given seasonal risks from wild waterfowl. Just days later, two additional outbreaks were reported nearby, raising the total number of affected birds in the state from roughly 20,000 to about 65,000, according to APHIS’ tracker (Soucheray, 2025).
First H5N1 Detection in Nebraska Dairy Cows
The USDA has confirmed Nebraska’s first ever case of H5N1 avian influenza in dairy cattle, detected through pre-movement milk sampling from a quarantined herd in the central part of the state (Animal and Plant Health Inspection Service, 2025). Genetic sequencing shows the virus belongs to clade 2.3.4.4b, B3.13 genotype—matching strains found in prior dairy outbreaks. Nebraska becomes the 18th state to report infected dairy cattle since 2024. While cattle detections had paused for over 30 days during summer, the confirmation tracks with the recent poultry outbreaks across the mid-West (Schnirring, 2025).
Montana Reports New Outbreak in Commercial Poultry
Montana has confirmed H5N1 avian influenza in a north central poultry flock—the state’s first domestic detection this fall and the first since March. According to USDA’s Animal and Plant Health Inspection Service (APHIS) tracker, the outbreak has affected approximately 5,800 birds. This marks Montana’s 32nd affected flock since 2022 (NBC Montana, 2025).
South Korea Reports First Regional H5N1 Outbreak of the Fall Season
South Korea has confirmed an outbreak of H5N1 on a poultry farm in Paju, Gyeonggi Province. The case prompted the Ministry of Agriculture to raise the national alert level from “attention” to “caution” and initiate culling, movement restrictions, and an epidemiological investigation. The early detection—weeks ahead of the usual October–November onset—has triggered nationwide inspections of poultry farms, traditional markets, and livestock transport systems to assess disinfection and containment protocols (Yonhap, 2025).
Taiwan Detects H5N1 in Changhua County, Culls 13,375 Hens
Taiwan has detected H5N1 avian influenza at an egg farm in Changhua County’s Fangyuan Township, a coastal region in western Taiwan. Following confirmation, authorities culled 13,375 hens and supervised disinfection measures. Officials warned that Taiwan’s location along the South Korea–to–Southeast Asia flyway increases the risk of further outbreaks, particularly after South Korea’s recently confirmed outbreak. The agency said the risk of additional cases will remain high for the next two to four weeks, and called on poultry farmers in coastal areas to bolster biosecurity (Yeh, 2025).
Poland Reports H5N1 Outbreaks on Two Northern Farms
Poland has confirmed H5N1 avian influenza on two poultry farms in the northern town of Susz, according to the World Organisation for Animal Health. The outbreak, affecting a goose farm and a turkey farm, killed about 4,000 birds. The detection comes shortly after Poland signed an agreement with China to restart poultry trade, which had been suspended following earlier outbreaks last year (Reuters Staff, 2025).
EU to Resume Brazil Chicken Imports After H5N1 Ban
The European Union will reopen its market to Brazilian chicken meat, lifting a ban imposed in May after an H5N1 outbreak in Rio Grande do Sul, according to Brazil’s agriculture ministry. Shipments from all regions except Rio Grande do Sul resume immediately, with most of that state cleared to export beginning October 2. At the same time, China has begun an audit of Brazil’s sanitary controls, the final step toward lifting its own restrictions. China remains the last major importer with a ban in place (Global Ag Media, 2025).
References:
Animal and Plant Health Inspection Service. (2025). USDA Confirms Highly Pathogenic Avian Influenza in Dairy Herd in Nebraska | Animal and Plant Health Inspection Service. Animal and Plant Health Inspection Service. https://www.aphis.usda.gov/news/agency-announcements/usda-confirms-highly-pathogenic-avian-influenza-dairy-herd-nebraska
Global Ag Media. (2025). EU to resume Brazil chicken imports after bird flu ban. Thepoultrysite.com. https://www.thepoultrysite.com/news/2025/09/eu-to-resume-brazil-chicken-imports-after-bird-flu-ban
Haiar, J. (2025, September 20). Over 400,000 turkeys killed in response to SD’s bird flu outbreak; ducks identified as carriers • South Dakota Searchlight. South Dakota Searchlight. https://southdakotasearchlight.com/2025/09/20/over-400000-turkeys-killed-in-response-to-sds-bird-flu-outbreak-ducks-identified-as-carriers/
Kaeding, D. (2025, September 25). Avian flu forces Jefferson County poultry farm to cull 3M birds. WPR. https://www.wpr.org/news/avian-flu-jefferson-county-poultry-farm-cull-3m-birds
NBC Montana. (2025, September 12). Avian influenza detected in north central Montana poultry flock. KECI. https://nbcmontana.com/news/local/avian-influenza-detected-in-north-central-montana-poultry-flock
Reuters Staff. (2025, September 22). Poland reports bird flu outbreak on farms in north, WOAH says. Reuters. https://www.reuters.com/business/healthcare-pharmaceuticals/poland-reports-bird-flu-outbreak-farms-north-woah-says-2025-09-22/
Schnirring, L. (2025, September 15). USDA confirms first H5N1 avian flu detection in Nebraska dairy cows. Center for Infectious Disease Research and Policy. https://www.cidrap.umn.edu/avian-influenza-bird-flu/usda-confirms-first-h5n1-avian-flu-detection-nebraska-dairy-cows
Soucheray, S. (2025, September 18). Minnesota reports first H5N1 detection in poultry since April. Center for Infectious Disease Research and Policy. https://www.cidrap.umn.edu/avian-influenza-bird-flu/minnesota-reports-first-h5n1-detection-poultry-april
Yeh, E. (2025, September 21). Dead chickens in Changhua test positive for H5N1. Taipeitimes.com; 台北時報. https://www.taipeitimes.com/News/taiwan/archives/2025/09/22/2003844217
Yonhap. (2025, September 13). Korea reports 1st highly pathogenic bird flu case for this year. The Korea Times. https://www.koreatimes.co.kr/southkorea/environment-animals/20250913/korea-reports-1st-highly-pathogenic-bird-flu-case-for-this-year