Saturday, October 25, 2025. This is your Bird Flu Bulletin: Daily H5N1 Update. I’m your host, reporting the latest on global H5N1 developments as of October Twenty-Fifth.

Top Stories:
First, Cambodia’s Ministry of Health has confirmed two new human H5N1 cases in young girls—one aged 14 from Takeo province and another from Kampong Speu, who is just three years old. According to the Centre for Health Protection in Hong Kong, the 14-year-old is currently hospitalized, while the three-year-old remains in intensive care. In both cases, local birds had recently shown signs of illness, suggesting environmental exposure. Cambodia’s total for the year now stands at 17 human H5N1 cases. These new infections involve a reassorted virus combining older Cambodian strains with the now globally dominant clade 2.3.4.4b.
Second, in China, four additional human H9N2 cases have been retrospectively identified, bringing the 2025 total to 25, up from 11 in 2024. These cases, reported in Guangdong, Guangxi, and Tianjin, underscore ongoing avian influenza activity in the region, albeit of a less severe strain.
Third, in the United States, the US Department of Agriculture reports over 6.3 million birds affected in 53 commercial and backyard outbreaks in the last 30 days, according to the latest Animal and Plant Health Inspection Service data. The most significant recent outbreak was in Washington state, impacting nearly two million birds in a single event. There has also been a confirmed cattle outbreak in Idaho, continuing the pattern of H5N1 jumping to mammals.

Case Numbers:
Globally, the World Health Organization is tracking H5N1 human cases with nearly a thousand reported since 2003, with a fatality rate close to 50%. However, most recent US cases—now totaling 70—have been mild, though one fatality occurred in Louisiana earlier this year.
There is no significant change in the US human case count since yesterday, but ongoing surveillance in both birds and mammals highlights the virus’s continued circulation. In Europe, 56 outbreaks have been recorded since August, mostly in Poland, Spain, and Germany, but numbers remain lower than during the 2022 peak. Meanwhile, suspected H5 avian influenza has been detected in wildlife on Heard Island, thousands of kilometers from the Australian mainland, but Australia itself remains H5-free.

Guidance and Statements:
The US CDC has simplified its avian influenza reporting to monthly updates, now integrating bird flu data with routine influenza surveillance. The APHIS remains the primary source for animal outbreak information.
Health authorities stress the importance of biosecurity on farms, especially with colder weather approaching. The US Agriculture Secretary recently noted an overall decrease in egg prices but warned that the fall and winter seasons could bring renewed challenges for turkey producers ahead of the holiday season.

Expert Snippet:
We spoke briefly with Dr. Amy Swinford, director of the Texas A&M Veterinary Medical Diagnostic Laboratory. “Because of the ongoing government shutdown, federal communication on avian flu is more limited than usual. Farmers, veterinarians, and public health officials need to remain vigilant—especially with Thanksgiving and Christmas approaching. Rapid detection and reporting are our best tools to limit spread.”

Looking Ahead:
Tomorrow, attention will focus on test results from wildlife samples collected on Heard Island and whether H5N1 is confirmed in species like elephant seals. Scientists are also closely watching for new human or animal cases in Cambodia and China. In the US, poultry producers are preparing for potential new outbreaks as wild bird migrations increase viral spread risk.
Internationally, the WHO and PAHO continue to monitor for any evidence of increased human-to-human transmission, which, thankfully, remains unobserved. Any...