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 more robust, farm-focused interventions.

Emerging variants, especially the dominant clade 2.3.4.4b, are showing greater adaptation in both birds and mammals and hint at increased potential for cross-species transmission. Bovine-origin strains have demonstrated environmental resilience and greater genetic diversity, raising concerns among public health officials.

As for travel, the European Centre for Disease Prevention and Control recommends that travelers avoid contact with wild birds or sick animals in active outbreak regions, particularly Cambodia, China, Mexico, and the American West. Agricultural workers are advised to enforce strict hygiene and biosecurity.

Thank you for tuning in to Avian Flu Watch: Global H5N1 Tracker. Stay informed and return next week for more up-to-date data and critical insight. This has been a Quiet Please production. For more, visit Quiet Please Dot A I.Back to Episodes