Identification of a Human Infection due to Highly Pathogenic Avian Influenza A(H5N1)

April 9, 2024

The CDC released a Health Advisory related to the investigation and response to confirmed human infection with highly pathogenic avian influenza (HPAI) A(H5N1) following exposure to infected dairy cattle.


The case was a farm worker on a commercial dairy farm in Texas. The individual developed a mild illness with conjunctivitis but no other symptoms and subsequently tested positive for HPAI A(H5N1) virus. This is the second person to test positive for HAPI A(H5N1) virus in the United States; the first case was identified in Colorado in 2022. This is also the first report of apparent spread of an HPAI virus from cow to human.


In response CDC has updated its guidance Highly Pathogenic Avian Influenza A (H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations.

Provider Recommendations and Resources

  • Providers should remind patients and the general public to avoid being near sick or dead animals.
  • Animals in which HPAI A(H5N1) virus infection has been identified include wild birds, poultry, other domesticated birds, and other wild or domesticated animals (including livestock such as cattle and goats).
  • As always, people should not prepare or eat uncooked or undercooked food or related uncooked food products, such as unpasteurized (raw) milk or raw cheeses, from animals with suspected or confirmed HPAI A(H5N1) virus infection.
  • Clinicians should consider the possibility of HPAI A(H5N1) virus infection in people showing signs or symptoms of acute respiratory illness or conjunctivitis and who have relevant exposure history outlined in Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations.
  • Providers considering HPAI A(H5N1) or any human infections due to novel influenza viruses should immediately contact the OCHCA Communicable Disease Control Division at 714-834-8180, to discuss clinical considerations and to assist with laboratory testing.

Additional Resources


For questions or concerns, please contact the Communicable Disease Control Division at 714-834-8180.

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