Health Update: Highly Pathogenic Avian Influenza Detections in the U.S.

Dairy Cattle, One Human Infection 

April 9, 2024

Action Requested 

• Be aware that highly pathogenic avian influenza (HPAI) H5N1 has been detected in dairy cattle in the U.S., and there has been one recent confirmed case of HPAI H5N1 in a human who worked on a farm with infected dairy cattle in Texas. No human cases have been reported in Washington.
  • More information is available from the CDC press release and the Health Alert from Texas Health and Humans Services.
• CDC has updated its interim recommendations for prevention, monitoring, and public health investigations.
• Consider the possibility of HPAI A(H5N1) virus infection in persons showing signs or symptoms of acute respiratory illness who have relevant exposure history. This includes:
  • persons who have had contact with potentially infected sick or dead birds, livestock, or other animals within the week before symptom onset (e.g., handling, slaughtering, defeathering, butchering, culling, preparing for consumption or consuming uncooked or undercooked food or related uncooked food products, including unpasteurized (raw) milk or other unpasteurized dairy products), direct contact with water or surfaces contaminated with feces, unpasteurized (raw) milk or unpasteurized dairy products, or parts (carcasses, internal organs, etc.) of potentially infected animals
  • persons who have had prolonged exposure to potentially infected birds or other animals in a confined space. 
• Contact the Health Department to arrange testing for influenza A(H5N1) virus and collect recommended respiratory specimens using PPE.
  • Call 425-339-3503 to reach the Snohomish County Health Department Communicable Disease program by phone.
• Consider starting empiric antiviral treatment, and encourage the patient to isolate at home away from their household members and not go to work or school until it is determined they do not have avian influenza A virus infection. 
• Testing for other potential causes of acute respiratory illness should also be considered depending upon the local epidemiology of circulating respiratory viruses, including SARS-CoV-2.
  • Testing of asymptomatic persons for HPAI A(H5N1) virus infection is not routinely recommended. As part of public health investigations, asymptomatic persons, such as close contacts of a confirmed case of HPAI A(H5N1) virus infection, might be tested after consultation with CDC.
• Standard, contact, and airborne precautions are recommended for patients presenting for medical care or evaluation who have illness consistent with influenza and recent exposure to birds or other animals potentially infected with HPAI A(H5N1) virus. For additional guidance, please refer to guidance for infections with novel influenza A viruses associated with severe disease.
• No human vaccines for prevention of HPAI A(H5N1) virus infection are currently available in the U.S. Seasonal influenza vaccines do not provide protection against human infection with HPAI A(H5N1) viruses.

For more information, see the full CDC release.

Background

A person has tested positive for highly pathogenic avian influenza (HPAI) A(H5N1) virus (“H5N1 bird flu”), as reported by Texas and confirmed by CDC. This person had exposure to dairy cattle in Texas presumed to be infected with HPAI A(H5N1) viruses. The patient reported eye redness (consistent with conjunctivitis), as their only symptom, and is recovering. The patient was told to isolate and is being treated with an antiviral drug for flu. This infection does not change the H5N1 bird flu human health risk assessment for the U.S. general public, which CDC considers to be low. However, people with close or prolonged, unprotected exposures to infected birds or other animals (including livestock), or to environments contaminated by infected birds or other animals, are at greater risk of infection. CDC has interim recommendations for prevention, monitoring, and public health investigations of HPAI A(H5N1) viruses.

This is the second person reported to have tested positive for influenza A(H5N1) viruses in the United States. A previous human case occurred in 2022 in Colorado. Human infections with avian influenza A viruses, including A(H5N1) viruses, are uncommon but have occurred sporadically worldwide. CDC has been monitoring for illness among people exposed to H5 virus-infected birds since outbreaks were first detected in U.S. wild birds and poultry in late 2021. Human illnesses with H5N1 bird flu have ranged from mild (e.g., eye infection, upper respiratory symptoms) to severe illness (e.g., pneumonia) that have resulted in death in other countries.

Resources

• Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations | Avian Influenza (Flu) (cdc.gov)
• Brief Summary for Clinicians: Evaluating and Managing Patients Exposed to Birds Infected with Avian Influenza A Viruses of Public Health Concern | Avian Influenza (Flu) (cdc.gov)
• Highly Pathogenic Avian Influenza (HPAI) Detections in Livestock | Animal and Plant Health Inspection Service (usda.gov)

Message categories

• Health Alert: High-importance information about a public health incident. Warrants immediate action.
• Health Advisory: Important information about a potential or ongoing public health incident. May not require immediate action.
• Health Update: Updates about an ongoing public health incident. Immediate action not required.