Avian Flu Watch: Global H5N1 Tracker

You’re listening to Avian Flu Watch: Global H5N1 Tracker. Today’s snapshot covers critical H5N1 avian flu developments as of November 2025, focusing on global spread, epicenters, transmission patterns, and public health interventions.

First, let’s break down current hotspots. According to the Pan American Health Organization, since 2022, 19 countries in the Americas have reported over 5,000 H5N1 outbreaks in birds, with 76 confirmed human infections and two deaths as of October 2025. The United States remains prominent, particularly West Coast states like California, where large-scale poultry and cattle operations have driven repeated clusters. A Nature Communications study models a significant disease burden in these Western states with persistent spread among dairy cattle, and highlights Arizona and Wisconsin as states at increased risk for emerging outbreaks.

In South America, Argentina, Chile, and Uruguay faced massive wildlife die-offs. More than 24,000 sea lions died in 2023–2024, and an outbreak among elephant seal pups in Argentina saw local mortality rates as high as 96 percent in some colonies. Across the continent, at least 600,000 wild birds and 50,000 mammals have died since 2022, reflecting the devastating spillover of H5N1 into non-avian species.

Turning to Europe, Germany has reported 2,000 dead cranes this year, and culled over 500,000 birds after 100-plus outbreaks — with significant clusters in battery farms. The European Centre for Disease Prevention and Control notes that most detections remain in Western and Southwestern Europe, but migratory birds continue to introduce the virus to new regions.

Asia reports human and animal cases along major migratory bird routes. China saw nearly 300 wild bird deaths in Qinghai this year, while Cambodia endured fatalities in children after contact with infected poultry. Genetic sequencing reveals both the dominant global 2.3.4.4b clade and emerging reassorted variants in Southeast Asia that combine gene elements from different H5N1 lineages.

Now, let’s visualize the global trend lines. On a hypothetical map, clusters would burn brightest in the Americas, the western US, and Southern Cone, with fading but persistent heat across Europe’s poultry corridors. Trend lines show a sharp increase in wild mammal deaths and a shift from sporadic poultry outbreaks to complex, multi-species patterns. Data from Our World In Data and the CDC chart the highest human case rates in the first and third quarters of 2025, corresponding with animal die-offs and migratory seasons.

Cross-border transmission is being shaped by bird migration and livestock trade. Geospatial research published in Geophysical Research Letters highlights that wild bird flyways crossing Eurasia and the Americas act as highways for new introductions, while fragmented farm quarantine policies have made containment patchy. A CDC analysis links multiple US states’ outbreaks to movement of infected cattle across state lines before federal testing was mandated in late April 2024. The result: viral hotspots that disregard national boundaries and seasonal migration patterns.

Containment successes are mixed. The United Kingdom’s mandatory animal testing and rapid poultry culls have limited large-scale spread, but sporadic mammal and human spillovers persist. In the US, interstate testing has identified outbreaks early, but interventions have yet to halt further farm transmission, as underscored by continued culling and economic losses.

Emerging variants of concern include Southeast Asian reassortants and genetically divergent strains in China, with experts warning of uncharted risks if these evolve increased transmissibility.

Today, the WHO maintains that human-to-human transmission remains rare. Still, they recommend travelers avoid live animal markets, farms, and wildlife...