The End of our Response, Not the End of the Risk: Our H5N1 Wrap-Up
Avian influenza emerged in dairy cattle in the U.S. in March 2024, marking the start of a nationwide outbreak. For over a year, Global.health (G.h) has tracked the virus as it impacted commercial cattle and poultry industries across the U.S. and crossed the species barrier from animals to humans. A total of 70 confirmed human cases across 13 states were detected (41 with dairy cattle exposure, 24 with poultry exposure and culling operations, 2 with other animal exposure, 3 with unknown exposure). Prior to this outbreak, only one human case had ever been detected in the U.S. This outbreak was an alarming indicator of zoonotic risk. At the end of our curation period, July 8th, 2025, the USDA had reported a total of 352 positive commercial poultry farms across 38 states and one U.S. territory, and 1,074 positive commercial dairy farms across 17 states. California, the epicenter of the outbreak, reported over half of all U.S. human cases, the largest number of infected dairy cattle farms, and second largest number of poultry farm outbreaks.
For zoonotic pathogens like avian influenza, timely, open access to both human and animal health data is essential. Early integration of these data streams can enable more accurate risk assessments, better situational awareness, and faster, more coordinated public health responses. However, the 2024-2025 outbreak exposed critical gaps in the U.S. surveillance infrastructure and revealed disjointed data systems. Data collection responsibilities are fragmented across federal, state, and local agencies, each operating within different mandates, formats, and timelines. As a result, data are delayed, reported inconsistently, or lack the granularity needed for meaningful analysis. This lack of interoperability and coordination undermines the ability to detect emerging threats in real time and mount a cohesive One Health response.
To fill these data gaps, G.h integrated disparate data sets, bringing together data and updates from government agencies, academic researchers, news sources, and more to enable a comprehensive view of the outbreak and help tell the story as it unfolded. Our Outbreak Resources are summarized in the following section.
G.h H5N1 Outbreak Resources
We created three publicly available outbreak resources:
1) an epidemiological line-list of human cases,
3) a multimodal data timeline that combines human cases, animal outbreaks, genomic data and wastewater surveillance data with policy changes, and research and response highlights.
These three tools work together to provide a real-time, cross-sector view of the outbreak. Our line-list provides detailed, deidentified case-level data to help characterize who was affected, where, their symptoms, outcomes, exposure conditions, and other key factors. Our interactive outbreak map visualizes the geographic overlap of human infections and animal detections, calling attention to zones where the virus is most active to help guide surveillance and response efforts. And our multimodal timeline, maintained in collaboration with ThinkGlobalHealth, weaves together 840 entries from diverse data sources into a single, integrated chronology that is openly accessible and easy to understand.
Enhanced Data Visualization
Data visualization is a core component of the G.h outbreak response. Using a One Health lens, we incorporated animal health data from the USDA and the WOAH—covering both cattle and poultry outbreaks—into our timeline events and as data overlays on our map. This brought human and animal cases into a single, comprehensive view. An integrated view can reveal insights, such as identifying areas at risk of animal-to-human transmission, that cannot easily be ascertained from individual datasets alone.
The End of our H5N1 Outbreak Response
On July 7th, 2025, the CDC ended its emergency bird flu response, citing a decline in new human and animal infections. With this development, the G.h team has decided to sunset our H5N1 timeline, bringing an end to more than a year of data collection and curation. The virus is still spreading, and we will continue to monitor the situation globally. However, we will no longer provide real-time data curation for U.S. animal and human cases. Our outbreak resources will remain accessible through the G.h website, GitHub, and ThinkGlobalHealth.org.
Ending an outbreak is not the same as eliminating the risk. As long as avian influenza exists in animals, we must remain alert to the possibility of spillover events, future human infections, and even pandemic risk. Given the virus’s ability to evolve and adapt, continued animal surveillance and human preparedness are essential.
From Data to Insight: What’s Coming Next
Want to learn more about our response to the avian influenza outbreak? We’re preparing a detailed summary of the 2024–2025 U.S. outbreak, highlighting key trends and insights from our application of integrated, multimodal data sources. We look forward to sharing more soon—stay tuned! As we wrap up our active response, we want to thank everyone who engaged with our avian influenza resources over the past year.
Until the next post,
The G.h Team