Status as of October 2, 2026

Highly pathogenic avian influenza (HPAI) H5N1 remains firmly established as an animal-health challenge in the United States. After the expected seasonal reduction in poultry outbreaks during portions of the summer, detections are again increasing as the country enters the fall migratory period. The current picture—continued infection of wild birds, renewed outbreaks in commercial poultry, continuing detections in dairy cattle, and ongoing occupational monitoring of exposed people—underscores how profoundly the epidemiology of H5N1 has changed since the current U.S. outbreak began in 2022.

Poultry outbreaks are increasing again

USDA Animal and Plant Health Inspection Service (APHIS) continues to characterize the HPAI outbreak in commercial and backyard poultry as ongoing. USDA notes that detections tend to increase during fall and spring migration and emphasizes the importance of examining the preceding 30 days rather than relying solely on cumulative numbers from the multiyear outbreak. (APHIS)

By late September, APHIS data summarized by the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP) showed H5N1 confirmed in 20 U.S. flocks during the preceding 30 days—13 commercial operations and seven backyard flocks—affecting approximately 560,000 birds. Six of eight newly reported outbreaks were in Minnesota, while additional outbreaks were reported in Wisconsin and Montana. A commercial turkey operation in Barron County, Wisconsin, involved approximately 79,100 birds, while two Minnesota turkey operations in Stearns County involved approximately 51,500 birds. (CIDRAP)

The increase follows earlier September activity in the Dakotas and Minnesota. Since September 1, APHIS had reported commercial poultry detections in North Dakota, South Dakota, Minnesota and Idaho. Among them were turkey operations involving approximately 61,300 birds in McPherson County, South Dakota; 43,800 in Turner County, South Dakota; 41,600 in LaMoure County, North Dakota; and 29,800 in Wright County, Minnesota. (CIDRAP)

These are not yet losses on the scale experienced during some of the worst periods of the current outbreak, but the direction of activity as fall migration accelerates deserves attention.

The wild-bird reservoir remains active

USDA’s wild-bird surveillance provides an important warning of what may lie ahead. APHIS reported recent detections in migratory species including mallards, blue-winged teal and Canada geese in states including Iowa, North Dakota, Wisconsin and Kansas. The APHIS database now contains nearly 20,000 wild-bird HPAI detections since the beginning of the current U.S. outbreak, although the agency cautions that some records reflect samples collected earlier and subsequently processed and reported. (APHIS)

Minnesota provides a particularly useful illustration of the relationship between the wildlife reservoir and poultry risk. In late September, the state reported at least 40 wild-bird H5N1 detections over approximately 10 days, involving mallards, Canada geese and bald eagles, while commercial poultry outbreaks were simultaneously increasing. (CIDRAP)

This persistent and geographically extensive wildlife reservoir is one of the fundamental differences between the current H5N1 situation and outbreaks for which stamping-out alone has historically been successful.

H5N1 remains established in dairy cattle

The expansion of H5N1 into dairy cattle has further changed the epidemiologic landscape.

USDA continues its National Milk Testing Strategy to identify affected states and herds through dairy-processing-plant silo monitoring, state surveillance, outbreak investigations and testing associated with interstate movement. The program is explicitly intended not simply to detect infection, but to identify where virus is circulating and support interventions intended to reduce transmission between livestock operations. (APHIS)

Dairy infections have continued during 2026. In September, APHIS data showed additional affected herds in Idaho and Texas; by that point, 88 dairy-herd detections had been reported during 2026. (CIDRAP) Earlier USDA data showed substantial activity in Utah and Idaho as well. (CIDRAP)

USDA’s own epidemiologic assessment recognizes that transmission within the dairy system can occur through livestock movement and through routine movement of people, vehicles and equipment between premises. USDA therefore continues to emphasize enhanced surveillance and biosecurity while vaccine candidates for dairy cattle undergo field trials. (APHIS)

The significance is difficult to overstate: H5N1 is no longer an infection moving only between wild birds and poultry. It now occupies an ecological and agricultural landscape involving wild birds, poultry, cattle and multiple mammalian species.

Human health risk remains low—but occupational exposure continues

The Centers for Disease Control and Prevention continues to assess the risk to the general U.S. public as low. CDC surveillance currently shows no unusual influenza activity in people attributable to avian influenza A(H5). (CDC)

Nevertheless, the occupational interface remains important. Since February 2022, state and federal public-health agencies have monitored at least 33,200 people following exposure to infected animals, and at least 1,340 have been tested for novel influenza A viruses. From September 28, 2025 through August 29, 2026 alone, at least 5,000 exposed people were monitored. (CDC)

CDC reports 71 human A(H5) cases in the United States since February 2024, most identified through active monitoring of people exposed to infected animals rather than routine influenza surveillance. (CDC)

There is currently no evidence of sustained person-to-person transmission in the United States. That is reassuring. But continuing opportunities for viral replication across multiple avian and mammalian hosts make continued animal and human surveillance essential.

What the fall resurgence tells us

The immediate response to an infected commercial poultry flock remains familiar: quarantine, depopulation, disposal, cleaning and disinfection, surveillance, and eventually repopulation. These measures can eliminate infection from an individual premises and are essential tools during an outbreak.

The more difficult question is whether this approach, by itself, remains an adequate national disease-control strategy for H5N1.

More than four years after H5N1 was first detected in U.S. commercial poultry in February 2022, the virus remains present in wild birds, continues to re-enter commercial poultry, has established transmission in dairy cattle, infects other mammals and periodically infects occupationally exposed people. USDA itself describes the poultry outbreak as ongoing and continues to invest heavily in biosecurity, surveillance and producer assistance. (APHIS)

The fall 2026 resurgence therefore reinforces the argument I have made previously: we should distinguish successful elimination of infection from an individual premises from successful control of H5N1 at the population level. They are no longer necessarily the same thing.

Depopulation can eliminate virus from an infected house or farm. It cannot eliminate H5N1 from migratory waterfowl. Nor can poultry depopulation by itself address infection circulating in cattle and other mammals.

That does not mean abandoning biosecurity, surveillance, rapid response or depopulation when it is epidemiologically necessary. It means adding additional tools and adjusting the objective.

Moving from repeated eradication attempts toward sustainable control

The United States should now have a serious, science-based discussion about transitioning from an almost exclusively stamping-out strategy toward a broader H5N1 control strategy.

That discussion should include targeted poultry vaccination; differentiation of infected from vaccinated populations through surveillance and appropriate diagnostic strategies; bilateral negotiations with trading partners before vaccination programs are implemented; continued genomic surveillance; strengthened wildlife surveillance; protection of agricultural workers; improved dairy-poultry biosecurity; and reconsideration of how infected poultry can be managed when immediate mass depopulation is not the only epidemiologically defensible option.

Vaccination should not be viewed as a substitute for surveillance or biosecurity. Properly implemented, it should be considered another disease-control tool.

Trade remains one of the most significant barriers. USDA and industry have legitimate concerns that vaccination could affect international market access. But after more than four years of continuing H5N1 circulation, the question should increasingly be whether trade policy should determine disease-control policy—or whether the United States should work proactively with individual trading partners and the World Organisation for Animal Health to establish scientifically defensible conditions under which vaccination and trade can coexist.

The latest fall detections do not by themselves prove that the current strategy has failed. They do demonstrate something more fundamental: H5N1 has not gone away.

The virus continues to exploit the connections among wildlife, domestic animals and people. Our response must increasingly reflect that biological reality.

For federal veterinarians, this is also a workforce issue. Every new outbreak requires veterinary epidemiology, diagnostics, field investigation, regulatory decision-making, biosecurity expertise, depopulation oversight, indemnity administration, surveillance and coordination with state, industry and public-health partners. Repeating an increasingly resource-intensive response indefinitely has consequences not only for producers and taxpayers but also for a federal veterinary workforce already being asked to respond simultaneously to multiple emerging and transboundary animal-disease threats.

HPAI H5N1 has become a long-duration national animal-health emergency. The challenge before us is no longer simply how rapidly we can respond to the next infected flock. It is whether the disease-control strategy itself continues to evolve as rapidly as the virus and its ecology have evolved.

Joseph F. Annelli, DVM, MS
Executive Vice President
National Association of Federal Veterinarians