Marin County Public Health is closely monitoring a multi-state outbreak of H5N1 bird flu in dairy cows with transmission to humans primarily in dairy and poultry workers. H5N1 bird flu was first detected among cows in California in August 2024. H5N1 bird flu was first detected among humans in California in October 2024.
H5N1 has been detected in both wild birds and poultry in Marin County. H5N1 has also been detected in wastewater. H5N1 has not been detected among livestock or farm workers in Marin.
In November, Marin County Public Health (MCPH) was notified of a suspected case of bird flu. The child presented to a local emergency department with fever and vomiting after drinking raw milk. The child tested positive for Influenza A. MCPH is working with California Department of Public Health (CDPH) and the Center for Disease Control (CDC) on additional testing to confirm if this infection was bird flu or seasonal flu. The child has recovered and no other family members became sick, indicating no person-to-person transmission.
People rarely get bird flu, but those who interact with infected dairy cows, poultry, or wildlife have a greater risk of infection. The current risk to the public remains low.
Health Care Providers: On December 6th, CDPH released an alert advising healthcare providers to consider avian flu in symptomatic persons who consumed raw milk products. Contact Marin County Public Health to coordinate testing for suspected avian influenza A (H5N1) in persons with signs and symptoms consistent with acute respiratory tract or gastrointestinal infection and/or conjunctivitis with history of consuming raw milk in the past 10 days. During business hours, call 415-473-4163 to coordinate testing.
Dairies & Cattle Farms: Call 1-866-922-2473 to report an unusual number of sick livestock or if you suspect Bird Flu in your livestock.
For more information, visit:
CDFA - AHFSS - AHB - H5N1 Bird Flu Virus in Livestock
CDPH Current Bird Flu Situation
CDC’s H5N1 Bird Flu: Current Situation Summary
Last reviewed and updated: December 10, 2024
What is H5N1 Bird Flu?
H5N1 bird flu is a specific strain or type of influenza virus. H5N1 bird flu is also called highly pathogenic avian influenza (HPAI). H5N1 bird flu can infect wild birds, poultry, and mammals such as cows. Human infections with H5N1 bird flu are rare, but spread of the virus may lead to changes that make it more likely to infect humans.
Public Health Recommendations
CDC has indicated that the current risk to the general public from H5N1 bird flu is low. People should:
- Wash your hands regularly, especially before eating and after interacting with animals.
- Avoid unprotected exposures to sick or dead animals including wild birds, poultry, and other domesticated birds. Handling sick or dead animals safely requires personal protective equipment and training.
- Do not drink or eat unpasteurized (raw) milk or raw cheese. Raw milk and cheese have not gone through a process called pasteurization that kills disease-causing germs. The milk of cows infected with H5N1 carries live virus. For more information about how raw milk can make you sick, visit the CDC’s Raw Milk web page.
Recommendations for Agricultural Workers and Animal Care Providers
People who have job-related or recreational exposure to infected animals, including wild birds, poultry, and dairy cows, are at greater risk of being exposed to H5N1 bird flu. People at higher risk should:
- Follow all CDC recommendations for worker protection to reduce the risk of infection
- Call your health care provider if you feel sick. Symptoms of H5N1 bird flu can include red or watery eyes, cough, sore throat, and fever.
The California Department of Public Health has also created educational fliers for agricultural workers and animal care providers about H5N1 bird flu. Please access the PDF here:
Additional Resources
- Avian Influenza (Bird Flu) Fact Sheet (California Department of Food and Agriculture)
- Avian Influenzas Updates (California Department of Food and Agriculture)
- Poultry Products Transportation (California Department of Food and Agriculture)
- Updates on Highly Pathogenic Avian Influenza (HPAI) (Food and Drug Administration)