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 gaps in surveillance hinder a full understanding of the epidemic scale and challenge timely response.

Recent months have seen the emergence of new H5N1 clade 2.3.4.4b variants, which exhibit increased host range and zoonotic potential. Notably, infections have jumped from birds to mammals like seals, goats, and cows, expanding risk. The CDC confirms that at least 20 mammalian species are now susceptible.

Travelers are advised to avoid direct contact with wild birds, poultry farms, and areas with confirmed outbreaks. International agencies recommend checking local health advisories and complying with import restrictions for animal products. Enhanced personal hygiene and vigilance remain essential, especially for those in or traveling to known hotspots.

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