Avian influenza A (H5N1) virus infection

Asymptomatic people

• There is currently no role for routine screening of the asymptomatic population outside of epidemiologic research studies. However, testing of asymptomatic people may be considered as part of ongoing public health investigations when feasible (e.g., workers with a high risk of exposure to infected animals who do not report wearing the recommended personal protective equipment, close contacts of a confirmed case).​​ Any person who develops signs or symptoms of acute respiratory illness or conjunctivitis after a high risk of exposure to highly pathogenic avian influenza (HPAI) A(H5N1) virus should be isolated and tested.[41]Centers for Disease Control and Prevention. Highly pathogenic avian influenza A(H5N1) virus: interim recommendations for prevention, monitoring, and public health investigations. Dec 2024 [internet publication]. https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html

Symptom monitoring in people with exposures

• All people who have been exposed to HPAI A(H5N1) virus-infected birds, cattle, or other animals should be monitored for symptoms consistent with infection starting on the first day of exposure and continuing until 10 days after the last exposure.[129]Centers for Disease Control and Prevention. Symptom monitoring among persons exposed to HPAI. Jun 2024 [internet publication]. https://www.cdc.gov/bird-flu/hcp/guidance-exposed-persons/symptom-monitoring-hpai.html

• Exposures include, but are not limited to, contact with:

  • Infected birds, livestock, or other animals

  • Carcasses of birds, livestock, or other animals

  • Feces or litter

  • Raw cow milk

  • Surfaces and water that may be contaminated with animal excretions.

• There are two types of monitoring recommended.

  • Active monitoring: local or state health departments contact exposed people directly about the development of signs and symptoms of infection on a specific schedule (this can be done using an application, email, or phone calls). This type of monitoring is recommended for people who have had unprotected exposures (e.g., dairy farm workers).

  • Self-monitoring: exposed people are provided with information about signs and symptoms of infection and who to contact if they develop these symptoms. This type of monitoring is recommended for people who used the recommended personal protective equipment (e.g., workers who are culling poultry).

• If an exposed person becomes ill during this period, antiviral treatment should be started and the person should be treated as a possible case.