The CDC has confirmed 36 human cases of H5N1 bird flu in the United States, with six new cases reported in Washington state and three additional cases in California. The outbreak, which started in April 2024, has primarily affected farm workers exposed to infected poultry and dairy cattle. While animal-to-human transmission has been confirmed, there is no evidence of person-to-person spread, and the CDC continues to monitor the situation closely.
Situation Update on H5N1 Bird Flu Outbreak
Since April 2024, the CDC, in collaboration with the USDA, FDA, and other partners, has been responding to a multistate outbreak of H5N1 avian influenza. The virus has infected both animals and humans, with confirmed cases in 16 states. Of the 36 confirmed human cases, 15 were linked to exposure to infected poultry, and 20 were associated with infected dairy cattle. One case in Missouri remains of unknown origin.
The newly confirmed cases in Washington state are the first in that region and occurred among poultry farm workers. Mild symptoms, such as eye irritation and upper respiratory issues, have been reported, but no hospitalizations have occurred.
Genetic Testing and Virus Surveillance
Laboratory testing has confirmed that all H5N1 cases in California belong to the B3.13 genotype, with no mutations found that would increase human transmissibility or reduce the effectiveness of antiviral treatments. The CDC continues to sequence and test samples from infected individuals to monitor any changes in the virus.
In Washington, virus isolation and genetic sequencing are still in progress. The CDC remains focused on ensuring that existing candidate vaccines for H5N1 are effective against the strains currently circulating.
Epidemiology and Prevention Efforts
The CDC is working with state health officials in California and Washington to conduct active surveillance of farm workers and community members exposed to infected animals. Field teams are assisting with symptom monitoring, testing, and providing antiviral treatments such as oseltamivir to those at risk.
Outreach efforts have expanded through targeted messaging via social media and local radio, particularly in areas affected by the outbreak. These efforts aim to educate farm workers and the public on the risks of H5N1 bird flu, the importance of personal protective equipment (PPE), and preventive measures, such as avoiding contact with sick or dead animals.
Recommendations to the Public
The CDC advises the public to avoid contact with sick or dead animals, animal waste, and unpasteurized milk from infected animals. People working with potentially infected animals should wear appropriate PPE to reduce their risk of exposure. Pasteurized milk remains safe to drink, as the process kills H5N1 viruses.
Public health officials continue to emphasize the importance of preventing the spread of H5N1 among both humans and animals, highlighting the work of the USDA and industry partners in containing the outbreak.
Ongoing Monitoring and Future Updates
The CDC is actively monitoring flu trends across the U.S., particularly in areas where avian influenza has been detected. To date, more than 6,100 people have been monitored for potential exposure, with over 55,000 specimens tested for H5N1 or other novel influenza viruses.
As the situation evolves, the CDC remains committed to providing timely updates on the outbreak, including ongoing efforts to protect public health and limit the spread of the virus.