Avian Influenza Outbreak in California Marine Mammals Contained After 'Herculean' Response

The avian influenza outbreak that threatened California's marine mammals has subsided, with no positive cases detected since March 14, 2026. A rapid, coordinated response involving multiple agencies and universities was key.

- The outbreak, first detected in February 2026, affected 64 animals out of 233 tested, with elephant seals the most impacted. - The virus was identified as HPAI H5N1 A3 genotype, likely spread from birds along the Pacific Flyway.

- Researchers used traditional observation, drone surveys, and satellite transmitters to monitor the outbreak. - The response serves as a model for future interagency action against zoonotic diseases.

The successful containment highlights the importance of established monitoring programs and rapid collaboration between researchers and agencies.