This is “Avian Flu Watch: Global H5N1 Tracker.”

Today we’re focusing on where highly pathogenic H5N1 is hitting hardest, how it is moving across borders, and what the numbers tell us about risk.

The Food and Agriculture Organization reports that since late September, countries have logged roughly one thousand new H5N1 outbreaks in animals across thirty‑plus nations, with the heaviest activity in Europe, East and Southeast Asia, and the Americas. In Europe, the European Centre for Disease Prevention and Control notes several hundred detections in domestic and wild birds between June and September 2025, concentrated in the United Kingdom, France, Spain, and Portugal, with additional clusters along the Nordic and Baltic coasts. In the Americas, FAO and the US CDC highlight persistent circulation in North American wild birds, poultry, and dairy cattle, plus new poultry outbreaks in Central America, including Guatemala.

On the human side, the US CDC reports 26 confirmed H5N1 infections worldwide between January and early August 2025, with most linked to direct exposure to infected birds or cattle and no sustained human‑to‑human transmission. A respiratory virus intelligence review from New Zealand’s PHF Science notes that Cambodia alone has reported 18 human H5N1 cases in 2025, several of them fatal, underscoring Southeast Asia as a key hotspot.

Imagine a world map dashboard. Hotspot circles over Western Europe and Southeast Asia are large and steady, while North and South America show smaller but growing clusters along migratory flyways and intensive farming regions. On a time‑series chart, global animal outbreaks trend upward from late 2024 into mid‑2025, then plateau at a high level. Human cases form a low, jagged line: numbers remain small but persistent, with Southeast Asia and the Americas providing most of the spikes.

Cross‑border transmission is being driven by wild bird migration and trade. A Nature analysis of the North American epizootic shows wild birds as the main long‑distance carriers of H5N1, seeding new foci as they move along flyways. A 2025 phylogeographic study from Uruguay traces two converging routes in South America: one avian‑derived pathway from Argentina into Uruguay and Brazil, and a second route linked to infected marine mammals moving from Chile along the Atlantic coast. These findings illustrate how the same viral clade can move through birds, seals, cattle, and back again, complicating control.

There have been notable successes. Early detection and rapid culling in several European countries have limited farm‑to‑farm spread, and coordinated surveillance networks in North America have improved real‑time tracking of wild bird positives. But failures are equally clear: late recognition of infection in dairy cattle in the United States allowed farm‑to‑farm transmission and spillover to workers, and patchy genomic surveillance in parts of South America means reassortant variants may go undetected.

Among emerging variants of concern, scientists remain focused on H5N1 clade 2.3.4.4b, which dominates the current panzootic and has acquired mutations associated with better replication in mammals. A reassortant detected during an Argentine outbreak in 2025, which picked up several internal gene segments from local low‑path viruses, is being closely watched for changes in virulence and host range.

For travelers, the World Health Organization and national agencies advise avoiding live bird markets and backyard poultry in affected regions, steering clear of sick or dead wild birds and marine mammals, and following local guidance on dairy and poultry products. Routine international travel continues, but people with occupational exposure to birds or cattle are urged to use personal protective equipment and to report respiratory or conjunctival symptoms promptly.

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This is “Avian Flu Watch: Global H5N1 Tracker.”

Today we are taking a data-driven look at how highly pathogenic H5N1 is moving across continents, species, and borders.

According to the UN Food and Agriculture Organization, since late September 2025 more than 950 H5 high-path avian influenza outbreaks have been officially reported in animals across 38 countries, with the heaviest concentration in Europe and the Americas. FAO notes that H5N1 remains the dominant subtype with zoonotic potential.

Region by region, here is the current picture.

In Europe, the UK government reports 64 confirmed H5N1 outbreaks in poultry in the 2025–26 season so far, including large commercial premises in Lincolnshire, Norfolk, and Devon. Protection zones of 3 kilometers and surveillance zones of 10 kilometers are repeatedly being imposed and lifted as new clusters are controlled.

The European Centre for Disease Prevention and Control and WHO describe ongoing detections in wild birds along the North Sea and Atlantic coasts, with spillover into poultry in the UK, France, the Netherlands, and the Iberian Peninsula. Trend lines for Europe show a clear winter uptick, consistent with earlier years: cases bottom out in late summer, then rise sharply from October as migratory waterfowl arrive.

In North America, the US Centers for Disease Control and USDA report that H5N1 remains widespread in wild birds and continues to cause outbreaks in poultry, with intermittent detections in dairy cattle and sporadic human infections. USDA’s wild bird dashboard shows new positives this autumn in Alaska and the Pacific Northwest, extending a multi-year epizootic first established in 2021. If you plotted these data, you would see a persistent plateau rather than a clean wave: the line never returns to zero.

In South America, a 2025 phylogeographic study in the journal Viruses shows that clade 2.3.4.4b H5N1 has spread through at least 10 countries, affecting over 80 wild bird species and 11 wild mammal species. The analysis reconstructs two major routes into Uruguay: one via wild birds and poultry moving from Argentina, and another via marine mammals and seabirds moving from Chile. On a map, these routes trace a V-shaped pattern converging on the Atlantic coast.

Cross-border transmission is being driven primarily by migratory flyways and shared coastal ecosystems. A geospatial modeling study published in 2024 highlights wintering wetlands and coastal stopover sites in Europe, West Africa, and the Americas as recurrent high-risk nodes. Visualize arcs along the East Atlantic, Mediterranean–Black Sea, and Americas flyways; outbreak dots cluster along those arcs, not political borders.

There have been notable containment successes. The UK and several EU states have rapidly culled affected flocks, imposed movement controls, and in France, expanded vaccination of ducks. These measures shorten outbreak duration and flatten the peak of poultry cases on national dashboards. By contrast, delayed detection and limited surveillance in parts of Africa and South America mean that trend lines there are more jagged, with long, slow declines.

On variants, WHO and ECDC continue to designate clade 2.3.4.4b H5N1 as the main concern, with occasional reassortant viruses such as H5N5 detected in wild birds in northern Europe. Genetic analyses from South America document mammal-adaptive mutations in PB2, raising concern about improved replication in non-avian hosts, though efficient human-to-human transmission has not been observed.

For travelers, WHO and CDC do not recommend general travel bans. Instead, they advise avoiding live bird markets and backyard flocks in affected regions, steering clear of sick or dead birds and marine mammals on beaches, and following local guidance on poultry products. For people working with birds or livestock, strict biosecurity, personal...

Good morning listeners. Welcome back to Avian Flu Watch: Global H5N1 Tracker, your data-focused window into the worldwide spread of bird flu. I'm your host, and today we're examining the latest epidemiological landscape as H5N1 continues its relentless march across continents.

Let's start with the geographic hotspots. According to the Pan American Health Organization, the Americas remain heavily impacted with 508 confirmed outbreaks in birds during 2025 alone across nine countries. The United States leads this count, with the vast majority of wild bird detections, particularly concentrated on the West Coast. Meanwhile, the Centers for Disease Control reports 71 confirmed human infections in the United States since 2024, with 41 cases linked to dairy herd exposure and 24 connected to poultry farm operations.

In Europe, the situation reflects concerning persistence. Between December 2024 and March 2025, 743 highly pathogenic H5N1 detections were reported across 31 countries, with predominant activity in central, western, and southeastern Europe. Africa and Asia continue experiencing significant circulation, with Cambodia recording three fatalities in 2025 alone among individuals with direct poultry exposure.

The trend lines tell an alarming story. Global data reveals that clade 2.3.4.4b, the dominant circulating strain since 2021, continues driving outbreaks worldwide. Unlike previous years where outbreaks peaked seasonally, this variant demonstrates sustained activity year-round. Our comparative statistics show that mammalian spillover events have increased dramatically, now documented across three continents with cattle, felines, and wild mammals all showing confirmed infections.

Cross-border transmission patterns reveal critical vulnerabilities. Wild bird migration networks serve as the primary dispersal mechanism, explaining how H5N1 spreads from Asia through Europe and down to Africa. Additionally, international cattle trade routes have become significant transmission corridors, particularly between the United States and Canada. Interstate cattle exports in America, subject to testing requirements of only 30 animals per cohort regardless of herd size, have proven insufficient to contain spread, with mathematical models predicting Arizona and Wisconsin as emerging outbreak hotspots.

Regarding containment success and failures: Thailand and Vietnam have demonstrated moderate success through enhanced surveillance and rapid culling protocols, yet their efforts remain challenged by persistent wild bird populations. Conversely, Cambodia's experience highlights containment failure, with three pediatric fatalities in early 2025 demonstrating how household-level transmission to young children exposed to infected poultry remains dangerously possible. The United Kingdom's single human case in early 2025 required immediate investigation, yet their response infrastructure prevented secondary spread.

Emerging variants demand attention. Beyond the dominant clade 2.3.4.4b, the United States recorded the first-ever human A(H5N5) infection globally in 2025, while Mexico documented an A(H5N2) case. These variant detections signal the virus's continued genetic evolution and reassortment potential, particularly concerning given H5N1's established 48 percent historical case-fatality rate across 991 documented human infections since 2003.

Travel advisories recommend heightened precautions in affected regions. The World Health Organization emphasizes that individuals traveling to Southeast Asia, particularly Cambodia and surrounding nations, should avoid live poultry markets and direct animal contact. Healthcare workers and farm employees in the Americas should maintain strict biosecurity protocols, including appropriate personal protective equipment usage. Raw milk consumption presents an underrecognized risk; the CDC documented multiple dairy worker infections, some...