This is Avian Flu Watch: Global H5N1 Tracker. Today is October 4, 2025.

The global threat posed by H5N1 avian influenza persists, with the latest data from the Food and Agriculture Organization showing 139 H5N1 outbreak events in animals recorded since late July across five major regions. The United States and the United Kingdom account for the largest share of these outbreaks, with the US confirming 3579 events since October 2024 and the UK close behind at 716. Notably, new clusters in Europe—particularly in France, Spain, and Belgium—indicate ongoing risk, while hotspots outside of Europe and North America include Argentina, India, China, Vietnam, and Cambodia.

When visualizing global H5N1 activity, trend lines show a persistent north-south pattern that mirrors migratory bird pathways. North America’s curve remains elevated since the surge last winter, with small declines now offset by outbreaks in new wild bird populations and occasional mammalian infections. Europe’s trajectory is nearly parallel, marked by a high baseline in wild and domestic bird cases, with seasonal spikes in coastal nations like Spain. In Asia, periodic clusters rise abruptly, often following poultry trade or migratory influxes. Africa, though less intensely affected, shows episodic wild bird die-offs—an area to watch closely.

Comparatively, current case numbers remain well above pre-2020 baselines. The US alone has reported more than double the H5N1 animal outbreaks seen in 2023. Several European countries, including France and Belgium, face a 30 to 50 percent increase in cases compared to last year. Human infection events remain relatively rare but have attracted scrutiny: In 2025, Cambodia reported three fatal human cases—involving direct poultry contact—while India, Mexico, and the United States each reported one human death. The UK detected an H5N1-positive farm worker and, unusually, an infected sheep producing milk contaminated with the virus, a development reminiscent of spillover events in US dairy cattle.

Cross-border transmission patterns underscore H5N1’s capacity for rapid regional spread. Phylogenetic studies published in the National Institutes of Health database have traced parallel genetic sequences of H5N1 between Turkey, Lebanon, Israel, and Egypt. These clusters reflect both migratory and trade-linked movement, highlighting how porous regional borders and shared poultry supply chains fuel outbreaks.

Containment measures have yielded mixed results. Countries like Norway and Portugal report quick culls and surveillance preventing multi-farm spread. In contrast, the US and UK continue to struggle with virus persistence in wild reservoirs, complicating eradication efforts. In South America, Argentina and Brazil have seen some localized success in limiting poultry-to-human exposure.

Viral evolution remains a key concern. Recent surveillance has detected H5N1 subtypes with mutations linked to better mammalian adaptation and immune escape. A handful of cases in mammals—such as cats, cattle, and foxes—in Europe and North America are being monitored as indicators of potential viral shifts. While none have yet demonstrated sustained human-to-human transmission, the risk remains under active review.

As a result, health authorities in outbreak hotspots—including much of the United States, the UK, Spain, and Cambodia—advise travelers to minimize contact with live birds and farms, avoid consumption of undercooked poultry, and follow local advisories on animal or dairy product recalls. Those in rural areas should practice enhanced biosecurity and immediately report sick or dead animals to officials.

Thank you for tuning in to Avian Flu Watch: Global H5N1 Tracker. Join us next week for the latest data, analysis, and expert perspectives. This has been a Quiet Please production. For more, check out Quiet Please dot A I.

For more Back to Episodes