CDC updates surveillance data for H5N1; infections remain linked to dairy herds and poultry operations with no person-to-person spread detected
WASHINGTON: The United States continues to monitor the spread of H5 bird flu as new federal data confirm 71 human cases since 2024, including two deaths, according to the latest situation summary from the U.S. Centers for Disease Control and Prevention (CDC). Despite the rising case count, the agency maintains that the current public health risk to the general population remains low.
H5 bird flu—formally known as highly pathogenic avian influenza (HPAI) H5N1—remains widespread among wild birds globally and continues to drive outbreaks in U.S. poultry farms and dairy cattle herds. The virus has also caused sporadic infections in people working closely with infected animals.
The CDC’s latest review shows:
- No person-to-person transmission has been identified.
- 41 cases were linked to dairy herds,
- 24 cases to poultry farms or culling operations,
- 3 cases to exposure from backyard flocks, wild birds, or other mammals, and
- 3 cases where the exposure source remains unknown.
Louisiana recorded the first H5-related death in the United States, while a previous poultry worker case in Colorado from 2022 remains documented.
Expanded Surveillance and Testing
Since early 2024, the CDC has conducted extensive flu surveillance to track possible human infections. More than 217,871 specimens have been tested nationwide for influenza A(H5) and other novel flu viruses, resulting in seven detections through routine surveillance channels.
Additionally, the agency has carried out targeted monitoring of individuals exposed to infected animals. More than 20,700 people have been monitored, and 960 have been tested, leading to 64 confirmed cases through this pathway.
The CDC recently streamlined its bird flu reporting schedule, moving some updates to a monthly basis. While human case numbers remain publicly available, updated data on animal detections will now be accessed directly through the U.S. Department of Agriculture (USDA).
Research and Ongoing Risk Assessment
The agency continues evaluating the virus’s mutation patterns and pandemic potential through its Influenza Risk Assessment Tool (IRAT). New findings highlight that influenza A viruses may also infect the gastrointestinal tract, causing digestive symptoms—an emerging area of interest for researchers.
Globally, 26 human infections were reported between January and August 2025. The CDC continues to coordinate with states, agricultural agencies, and global health bodies to track the evolving situation. For now, officials emphasize that the risk to the general public remains low, but close monitoring continues as the virus spreads among animals and sporadically infects people through occupational exposure.
