A strain of the deadly avian flu detected in Ano Nuevo State Park last month, with cases confirmed in California marine mammals for the first time ever, has been documented in another new county hundreds of miles south of the initial outbreak.
On Thursday, UC Davis’ Institute for Pandemic Insights reported a case of HPAI H5N1 was confirmed in a dead California sea lion found on a beach in San Luis Obispo. The animal was approximately one to two years old, and the third known sea lion to contract the virus since the start of the outbreak, with the other two individuals found in San Mateo County.
“Juvenile sea lions are known to forage along the central California coast traveling as far south as the primary sea lion breeding colonies on the Channel Islands,” the news release read. “Researchers are continuing to monitor marine mammal populations all along the coast.”
In a recent press conference, wildlife experts confirmed the disease that has been found in 27 northern elephant seals, killing at least 47 of them, has also spread to at least one southern sea otter.
The latest case was sampled by a researcher from the Central California Marine Animal Response Team (CCMART) on March 16 and confirmed by UC Davis and the USDA’s National Veterinary Services lab on March 25. “This is the first report of HPAI in a marine mammal from San Luis Obispo County,” the statement reads.
The sea lion was found along Morro Strand State Beach in Morro Bay, the San Luis Obispo County Public Health Department said in a Friday news release. While the risk of virus transmission to people remains low, officials cautioned against approaching marine mammals or seabirds on beaches. “This is especially important for animals that appear sick, injured, or deceased,” the department said.
Instead, people are encouraged to report sightings of sick or injured marine mammals by calling the NOAA West Coast Marine Mammal Stranding Hotline at 866-767-6114. Sightings of sick or injured birds can be reported to the California Department of Fish and Wildlife by calling 916-358-2790.
Earlier this month, officials said the virus was detected for the first time at Point Reyes National Seashore in a dead common murre. Staff began to notice an uptick in deceased seabirds on Feb. 25, around the same time the first cases were identified in marine mammals at Ano Nuevo State Park.
The increase in dead birds was linked to “a broader regional seabird mortality event” sweeping through beaches across the Bay Area, Point Reyes National Seashore spokesperson Earl Perez-Foust wrote at the time. He noted that while coinciding reports of avian flu in marine mammals have “increased regional interest in the disease,” no signs of illness have been confirmed in the northern elephant seal colony at Point Reyes National Seashore.
Public health officials said positive cases of bird flu were first confirmed in San Luis Obispo County in 2022. People are encouraged to contact the department with questions by calling 805-781-5500.