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, delaye

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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 domin

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# AVIAN FLU WATCH: GLOBAL H5N1 TRACKER

PODCAST SCRIPT

Welcome to Avian Flu Watch, a data-focused tracking program examining the worldwide spread of H5N1. I'm your host, and today we're breaking down the latest epidemiological landscape with hard numbers and geographic precision.

Let's start with the Americas. The Pan American Health Organization reports that in 2025 alone, nine countries have confirmed 508 outbreaks in birds, with thousands of wild bird detections concentrated in the United States and Canada. Since 2022, nineteen countries and territories have reported 5,136 animal outbreaks total. Human infections remain rare but present. The Americas have documented 75 H5N1 cases since 2022, resulting in two deaths. In 2025 specifically, we've seen three cases in the United States and one in Mexico, alongside one H5N2 case and notably, one H5N5 case in the United States, marking the first global H5N5 human infection.

Moving to Asia, the picture darkens considerably. Cambodia has emerged as a critical hotspot, with 18 confirmed H5N1 cases in 2025. The World Health Organization documented three deaths in early 2025, including cases in children with direct poultry exposure. Between January and August 2025, global figures reached 26 human H5N1 infections, with Cambodia accounting for a significant portion. China reported six A(H9N2) cases and one A(H10N3) case during the December 2024 to March 2025 period.

Europe's surveillance data reveals 743 highly pathogenic H5N1 virus detections across 31 countries between December 2024 and March 2025, split between 239 domestic birds and 504 wild birds. The predominant clade 2.3.4.4b continues driving European activity, concentrated in central, western, and southeastern regions.

Regarding containment measures, the United States implemented interstate cattle testing protocols in April 2024, requiring testing of up to 30 randomly selected cattle before export approval. However, mathematical modeling suggests these measures have prevented only a mean 175.2 reported outbreaks, proving insufficient to control spread. Stronger farm-focused biosecurity interventions remain urgently needed. Epidemiological models predict Arizona and Wisconsin face greatest outbreak risk, with continued dairy spread anticipated throughout 2025.

The transmission landscape reveals critical patterns. Wild birds played the central role in dispersing the 2021-2023 H5N1 epizootic, according to recent ecological studies. Cattle movement between herds enabled novel 2024 dairy transmission in the United States. The Pan American Health Organization urges reinforced surveillance in higher-risk populations including poultry farmers, veterinarians, and farm workers.

Variant evolution presents ongoing concerns. Clade 2.3.4.4b genetic diversification with other clades has expanded the virus's ability to infect broader mammalian species. The first documented human H5N5 infection in the United States and emergence of H5N2 and H5N3 variants und

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AVIAN FLU WATCH: GLOBAL H5N1 TRACKER

Welcome to Avian Flu Watch, a data-focused exploration of the worldwide bird flu landscape. I'm your host, and today we're examining the current state of H5N1 transmission across the globe as of December 2025.

Let's start with the numbers. The FAO reports that since late September 2025, 954 avian influenza outbreaks have been documented across 38 countries and territories. The H5Nx subtype dominates with 661 cases, followed by H5N1 with 286 confirmed outbreaks, H5N5 with 4 cases, and smaller numbers of H7Nx and HxNx variants. These figures represent an unprecedented scale of animal-level transmission.

In terms of human infections, the CDC confirms 71 cases of H5 bird flu in the United States since 2024, with one confirmed death in Louisiana. Forty-one cases originated from dairy herds, twenty-four from poultry farms and culling operations, three from other animal exposures, and three from unknown sources. California leads with thirty-eight cases, followed by Washington state with twelve and Colorado with ten. This geographic concentration reflects the dairy industry distribution and cattle movement patterns.

Globally, the epidemiological picture is more sobering. Since 2003, more than 890 sporadic human infections with H5N1 have been reported across twenty-three countries, with approximately fifty percent resulting in mortality according to WHO data. The recent 2024-2025 outbreak in the United States has intensified public health concerns.

Wild birds remain the primary transmission vector. The USGS reports that H5N1 has been detected in over ten thousand wild birds representing more than 160 unique North American species since the panzootic began in late 2021. These migratory populations are driving continental and even circumpolar spread patterns. Recent detections in November 2025 across Washington, Idaho, and Missouri indicate active circulation.

The dairy cattle outbreak presents a novel concern. A mathematical model from research institutions predicts that West Coast states, particularly California, will continue experiencing concentrated outbreaks through 2025 due to existing trade patterns with Texas and larger average herd sizes. The model forecasts that Arizona and Wisconsin face greatest risk for emerging infections. Interstate cattle movement, despite testing requirements for exports of more than thirty animals, remains insufficient for containment. Current interventions have prevented only an estimated 175 reported outbreaks.

Emerging data reveals troubling transmission routes. The bovine-origin H5N1 has demonstrated spread from infected cattle to poultry, domestic cats, raccoons, and rodents. More significantly, kittens have become infected through consumption of raw milk containing the virus, while CDC reports multiple dairy worker infections linked to raw milk exposure. This represents a paradigm shift in zoonotic transmission understanding.

Internationally, the Pan American Health Organ

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# AVIAN FLU WATCH: GLOBAL H5N1 TRACKER

Hello, I'm your host, and welcome to Avian Flu Watch, where we track the global spread of H5N1 bird flu with the latest data and analysis. Today we're examining a pandemic threat that continues to evolve across continents, affecting wildlife, livestock, and human populations.

Let's start with the current global picture. As of August 2025, the World Health Organization reports nearly 1,000 cumulative human cases of H5N1 since 2003, with a concerning 48 percent fatality rate across 25 countries worldwide. However, recent transmission patterns reveal a dramatic acceleration. Between June and September 2025 alone, 19 new human cases emerged across just four countries, including three deaths. This clustering suggests changing epidemiology that demands our attention.

Geographically, the outbreak presents distinct regional hotspots. Cambodia has emerged as perhaps the most alarming epicenter, reporting 11 H5N1 cases during the June-September period, predominantly in children with direct exposure to infected poultry. India reported one case, Bangladesh one case, and China documented additional infections with variant H5N1, H10N3, and H9N2 strains. Meanwhile, the Americas have experienced massive outbreaks in animal populations. As of mid-October 2025, 19 countries and territories in the Americas reported over 5,000 avian influenza outbreaks, with 76 human infections resulting in two deaths between 2022 and October 2025.

The United States presents a particularly complex situation. In 2024, H5N1 invaded dairy cattle operations, a novel development that shifted outbreak dynamics dramatically. Mathematical modeling indicates the majority of disease burden concentrated in West Coast states, with California alone reporting more than eight times the outbreaks of any other state. However, the model predicts significant under-reporting in Midwest states, with Arizona and Wisconsin identified as highest-risk areas for undetected transmission. Current federal testing requires up to 30 cattle from exported cohorts to test negative before interstate movement is permitted. Yet modeling analysis shows this border testing intervention alone prevents only 175 mean reported outbreaks and remains insufficient for epidemic control.

A critical emerging concern involves variant evolution. The dominant strain involves H5N1 clade 2.3.4.4b, which has demonstrated expanding host range, infecting terrestrial and marine mammals previously considered low-risk. Since 2022, 22 countries across three continents reported mammal outbreaks to the World Organization for Animal Health. In South America, H5N1 killed an estimated 600,000 wild birds and 50,000 mammals since 2022, devastating seal populations with mortality rates reaching 96 percent in surveyed areas.

Cross-border transmission patterns reveal wild bird migration as the central dispersal mechanism for the 2021-2023 epizootic. Cattle movement through interstate trade networks drives do

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# Avian Flu Watch: Global H5N1 Tracker

Welcome to Avian Flu Watch, your weekly briefing on the worldwide spread of H5N1 avian influenza. I'm your host, and today we're tracking a virus that continues to evolve and expand across continents.

Let's start with the numbers. As of late November 2025, the World Health Organization reports 991 human cases of H5N1 have been documented since 2003, with a concerning 48 percent case fatality rate across 25 countries worldwide. More alarming, between November 2024 and May 2025 alone, an additional 24 cases emerged in the United States, bringing the domestic count to 70 infections. The majority of these—41 cases—involved exposure to infected dairy cattle, representing a significant shift in transmission patterns.

Geographic hotspots paint a complex picture. In Southeast Asia, Cambodia experienced three fatal human infections in 2025, with victims ranging from a 28-year-old man to a three-year-old child exposed to infected poultry. India reported a fatal case in April, while Mexico documented its first human death in the same month, a three-year-old girl. The Americas now account for the densest cluster of infections globally, with nine countries confirming 508 bird outbreaks in 2025 alone.

Within the United States, the West Coast dominates current outbreak distribution. Mathematical modeling indicates that California, Texas, and neighboring states represent the primary disease burden, with West Coast dairy operations reporting over eight times more outbreaks than any other region. Arizona and Wisconsin emerge as states at greatest risk for imminent detection, despite potentially harboring undetected infections already.

The dairy cattle outbreak trajectory deserves particular attention. Starting in Texas and spreading through interstate cattle commerce, the virus has adapted to establish itself in a new host population. By December 2024, transmission models predicted a uniform probability of infection across multiple states, with federal orders requiring testing of only thirty animals per exported cohort—a measure experts describe as insufficient for genuine control.

Regarding containment efforts, international responses show mixed results. Current interventions—primarily interstate testing protocols—have prevented approximately 175 reported outbreaks but remain inadequate according to epidemiological modeling. Stronger farm-focused biosecurity measures are needed but remain largely unimplemented. In contrast, the development and deployment of H5N1 surveillance systems in wild bird populations has provided valuable early warning capabilities.

Variant evolution presents ongoing concern. The dominant strain worldwide is clade 2.3.4.4b, which has demonstrated increased capacity to infect mammals beyond traditional avian species. Wild birds continue dispersing the virus across continents, with detections now spanning from North America to Europe, Sub-Saharan Africa, and East Asia.

Travel advisories remain c

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This is Avian Flu Watch: Global H5N1 Tracker. Today’s episode brings you the latest scientific analysis on the evolving threat of avian influenza across continents, with a focus on data-driven insights and transmission patterns shaping global health responses as of November 2025.

Worldwide, the impact of H5N1 remains severe. According to the World Health Organization, as of November 2025, 993 confirmed human cases have been reported since 2003, with 476 fatalities—a case fatality rate near 48 percent. This year, new spillover events highlight persistent risks, particularly in the Americas and Southeast Asia. In Cambodia, recent cases have pushed their national tally to 90 since 2003, with 52 deaths. India and Mexico both reported fatal cases earlier this year, a troubling sign of the virus’s persistent mobility. The CDC notes that, between January and August 2025, there were 26 new human infections worldwide, with a cluster linked to bovine exposure in the United States.

Animal outbreaks remain extensive. The Food and Agriculture Organization documents nearly 1,000 new events in 38 countries since September, hitting both poultry and mammals. The epicenter in North America is the U.S. West Coast, where mathematical models show the greatest concentration of infected dairy herds, especially in California—a state reporting over eight times more outbreaks than any other. Arizona and Wisconsin are flagged as the most at-risk for new herd outbreaks in coming months, based on interstate cattle movement and herd sizes.

Visualizing the spread, global maps show multiple red-hot zones: Western Europe has persistent wild bird and poultry outbreaks, while southern Canada and the U.S. sustain overlapping animal epidemics. Asia presents concentrated clusters in China and Cambodia. Trend lines chart a steep increase in animal outbreaks from mid-2024, reaching a new plateau by September 2025, largely tracking seasonal bird migrations and cross-border animal trade.

Statistically, the West Coast of the United States shoulders the highest disease burden among cattle, while Europe and Southeast Asia remain the global hotspots for avian and mixed-mammalian cases. When comparing continents, the Americas have seen the largest year-on-year increase in mammal infections since 2022.

Cross-border transmission remains a major challenge. Mathematical modeling published in 2025 highlights that interstate movement of cattle in the U.S.—often without sufficient testing—has enabled H5N1 to hop rapidly from Texas to the West. Only exported cattle are systematically tested, meaning internal state movements can bypass surveillance, enabling silent viral spread.

Containment successes have emerged in some areas. Rwanda, for example, declared its first outbreak over in December 2024 through strict local restrictions. However, containment failures remain widespread: U.S. border testing, while a necessary surveillance step, has not significantly curbed the epidemic, with calls for m

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This is Avian Flu Watch: Global H5N1 Tracker.

Today, we’re mapping the latest footprint of H5N1 highly pathogenic avian influenza. As of mid-November 2025, the World Health Organization and the European Centre for Disease Prevention and Control confirm 993 human cases globally since 2003, including 476 deaths, with over a dozen cases and several fatalities reported just in the last year. These numbers underscore a stubborn and evolving pandemic threat.

Let’s break down current geographic hotspots. The Americas have seen a surge, especially in the United States, where mathematical modeling from US researchers indicates ongoing outbreaks concentrated along the West Coast, notably in California and Texas, with Arizona and Wisconsin at high risk for imminent spread. The US Centers for Disease Control and Prevention reports that over 60 human cases have occurred in the US this year, including clusters linked to dairy cattle and raw milk exposure.

In Europe, transmission remains high in southwestern and western regions, with recent outbreaks in Portugal, Spain, Hungary, Iceland, and Poland. Community-level surveillance has also been ramped up in Cambodia after fatal human cases in early and late 2025. Reports from China and India highlight persistent poultry-to-human spillovers, reinforcing Southeast Asia as a key zone of concern.

Looking at comparative statistics, the global case fatality ratio continues to hover near 48 percent. This is a stark reminder that H5N1, while still rare in humans, is often deadly when infection occurs. During October and November, monthly global reports have shown a rising trend line in outbreaks among birds and mammals, especially in countries with intensive poultry and dairy operations.

Visualizing the spread, one would see a heat map glowing along transcontinental migratory bird routes, with streaks tracing wildfowl pathways from Siberia through Europe and into Africa and the Americas. According to Nature, wild birds remain the main dispersal vector between continents, but recent mathematical models show increasing cross-border livestock transmission, especially via trucked cattle in North America.

This cross-border linkage is further amplified by trade and insufficient farm biosecurity. For example, U.S. measures involving random testing of up to 30 cattle per interstate export have slowed, but not halted, the epidemic’s growth. The response in Asia has generally been more aggressive, with periodic bans on poultry movement and culling of exposed animals, though sporadic enforcement gaps do persist.

Notably, new variants of concern are emerging. The clade 2.3.4.4b dominates globally, with studies warning it can cross species barriers in unexpected ways—recent bovine-origin transmissions in the US and Europe have shown evidence of non-traditional infection routes, such as viral contamination of raw milk consumed by other animals. Researchers emphasize heightened vigilance for reassortant strains and continued moni

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Avian Flu Watch: Global H5N1 Tracker

Welcome to Avian Flu Watch, your data-focused update on the global spread of H5N1 avian influenza as of November 19, 2025. Today’s episode examines current hotspots, transmission patterns, containment efforts, emerging variants, and guidance for travelers—all grounded in the latest international surveillance and reporting.

Globally, H5N1 activity remains high. The World Health Organization reports that since 2003, there have been 990 confirmed human cases in 25 countries, with 475 fatalities—a case fatality rate near 48 percent. Since October 2025 alone, 954 animal outbreaks have been reported in 38 countries, 286 of which involved H5N1 specifically according to the Food and Agriculture Organization.

Here’s a geographic breakdown of current hotspots:

- In the Americas, 19 countries and territories have reported a total of 5,063 recent H5N1 outbreaks, with 76 human cases and two deaths between 2022 and October 2025, as confirmed by the Pan American Health Organization.

- In Asia, Cambodia stands out as a major epicenter with 11 newly confirmed human cases of H5N1 between June and September 2025 and three deaths. Bangladesh and India each reported one new case in the same period.

- In Europe, outbreaks persist across the EU, particularly impacting wild bird and poultry populations, as noted by the European Food Safety Authority.

- In Africa and the Middle East, sporadic outbreaks have been registered, but case numbers are substantially lower than in the Americas and Asia.

Visualizing the data, global trend lines show recurrent seasonal surges, notably in winter months, correlating with migratory patterns of wild birds. Outbreak charts from Our World in Data display peaks in human infections during early 2025, with smaller spikes in late spring and fall.

Comparatively, the Americas have seen a steep rise in animal outbreaks, while Southeast Asia experiences higher human case incidence, often linked to rural poultry exposure. In the US, CDC modeling indicates the majority of animal cases are concentrated in West Coast states, with California reporting eight times more outbreaks than any other state. Arizona and Wisconsin are flagged as next at-risk states due to their herd sizes and trading patterns.

Cross-border transmission remains a defining feature of the global H5N1 landscape. The movement of infected wild birds and trade in livestock are major drivers. Mathematical modeling from US veterinary data demonstrates that current border testing—sampling up to 30 cows per interstate livestock shipment—detects cases but fails to significantly curb spread. Enhanced farm-focused biosecurity is urgently recommended.

International containment responses vary in success. The US implemented mandatory testing of exported livestock, which slowed but did not stop transmission. Argentina suspended poultry exports after confirming local outbreaks, helping contain further international spread. However, under-reporting and

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This is Avian Flu Watch: Global H5N1 Tracker.

From 2020 to now, H5N1 avian influenza has swept the globe, striking every continent except Australia, and intensifying in 2025. The World Health Organization reports that, as of August, there have been 990 confirmed human H5N1 cases since 2003, including 475 fatalities worldwide—a mortality rate near 48 percent. In 2025 alone, over 26 new human infections have been registered, with case clusters emerging in the Americas, Europe, Asia, and parts of Africa.

Let’s break down the current hotspots. In the Americas, the Pan American Health Organization confirms that since 2022, 19 countries have encountered 5,063 outbreaks. The U.S. dominated headlines with the first H5N1 cases in dairy cattle—over 17 states affected—California now leads with eightfold more herd outbreaks than other states, while Arizona and Wisconsin are flagged as rising epicenters. Human infections linked to livestock have surfaced, especially among dairy workers. Mexico and Argentina have reported fatalities, and notable transmission into wildlife threatens ecosystem disruption.

In Europe, Germany faced 103 outbreaks between June and September—culling over 500,000 birds—and Hungary lost 10,000 migratory cranes. The UK recently reported a poultry worker infection and even documented mammalian cases, suggesting expanded host risk. Between June and September, the European Centre for Disease Control records 19 human cases in the region, with three deaths. Asia remains vigilant with outbreaks in Cambodia, China, Bangladesh, and India. Cambodia, particularly, observed 11 new cases and two deaths since June, many in children exposed to sick poultry.

Visualizing global trend lines, avian flu’s graph surged sharply in wildlife in early 2024, plateaued in mid-2025, but with persistent spikes among livestock and sporadic human spillover, especially in high-density poultry regions and integrated farm systems. Infection rates for mammals continue to climb, with cattle-linked transmission increasing. Transmission models and geospatial studies show viral spread is primarily dictated by migratory bird pathways and trade. Regions with live bird markets, overlapping livestock sectors, and lax biosecurity remain high-risk.

Cross-border transmission is driven by wildlife migration, shared livestock operations, and uncontrolled animal trade. Case clusters trace to farms with scant safety protocols and places where personnel move freely between poultry and cattle zones, underscoring the need for better surveillance and targeted control.

Turning to international containment, some countries have demonstrated partial success. U.S. efforts with mandatory cattle testing and poultry culling have slowed spread but not halted it. Germany’s mass culling staved off larger outbreaks but led to economic strain. In contrast, regions with little biosecurity—particularly South and Southeast Asia—have struggled to curb transmission, reflected by ongoing human fatalit

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