H5N1 Avian Flu Persists in 2025: Cambodia Leads Global Hotspots with Continued Poultry and Dairy Transmission Risks

Avian Flu Watch: Global H5N1 Tracker Today’s date is August 11, 2025. Here’s the data. Hotspots and case counts - Cambodia remains the most active human hotspot in 2025. According to WHO, Cambodia reported 11 laboratory-confirmed H5N1 human infections between January 1 and July 1, 2025, with six deaths and exposures linked to backyard poultry across eight provinces; since the 2003 start of global records, WHO counts 986 human H5N1 cases across 25 countries with a long-run case fatality near half. Source: WHO Disease Outbreak News, July 5, 2025. - CDC’s global summary through August 4, 2025 reports 26 human H5N1 infections worldwide in 2025, 23 outside the U.S., with 11 deaths. The U.S. has had three cases in 2025, with no reports since mid-February; no person-to-person spread identified. Source: CDC, Global Summary of Recent Human Cases of H5N1, August 4, 2025. - Beyond humans, animal outbreaks remain widespread. The World Organisation for Animal Health reports continued highly pathogenic avian influenza circulation in wild birds and poultry, sustaining spillover risk. Source: WOAH, Avian Influenza, July 28, 2025. Trends and visualizations - Picture a line chart of weekly 2025 human cases: a low, steady baseline Jan–May, then a June uptick centered in Cambodia, leveling by early July per WHO line listings, with a flat U.S. line since mid-February per CDC. - A stacked bar comparison shows 2025 fatalities concentrated in Cambodia, India, and Mexico, matching CDC’s 11 deaths year-to-date. - A heat map of animal detections would highlight persistent hotspots along major migratory flyways, aligning with WOAH reports of sustained circulation in wild birds and poultry. Cross-border transmission patterns - Phylogenetic analyses indicate regional cross-border movement in the Middle East, with genetic links among Turkey, Lebanon, Egypt, Israel, Gaza, and Kuwait, consistent with poultry trade and shared flyways. Source: Phylogenetic Analysis and Spread of HPAI H5N1 in Middle Eastern Countries, May 20, 2025 (PMC). - Globally, migratory birds and dense poultry systems continue to connect ecosystems, enabling transcontinental spread of clade 2.3.4.4b. Source: Frontiers in Cellular and Infection Microbiology, July 25, 2025. Containment successes and failures - Success: In the U.S. dairy sector, modeling indicates interstate testing and the federal order reduced spread compared with a no-restrictions scenario; earlier and stronger testing would have further curtailed transmission. Source: Nature Communications modeling study, May 8, 2025. - Ongoing challenges: Cambodia’s backyard poultry exposures and live bird handling continue to drive sporadic human infections despite responsive case investigations and culling, per WHO. Emerging variants of concern - Clade 2.3.4.4b remains dominant in birds with documented cross-species spillover potential. Source: Frontiers review, July 25, 2025. - A newly identified cattle-associated variant D1.1 was detected in Nevad This content was created in partnership and with the help of Artificial Intelligence AI.