The University of California-Davis has confirmed the first cases of highly pathogenic avian influenza (HPAI) in seven northern elephant seals in California.
The outbreak marks the first H5N1 detection in marine mammals in California, and the first detection of the virus in northern elephant seals. The seals lived at the Ano Nuevo Natural Reserve, where researchers were called late last week after reports of sick animals with abnormal respirations, tremors, and neurological symptoms.
“This is exceptionally rapid detection of an outbreak in free-ranging marine mammals,” said Christine Johnson, PhD, director of the Institute for Pandemic Insights at the UC Davis’ Weill School of Veterinary Medicine, in a press release. “We have most likely identified the very first cases here because of coordinated teams that have been on high alert with active surveillance for this disease for some time.”
Samples taken from deceased seals showed H5N1 late Tuesday night. Though this is California’s first experience with H5N1 crossing over to marine mammals, the virus killed large swaths of Argentina’s southern elephant seals in 2023.
Ano Nuevo State Park, near Santa Cruz, is home to 5,000 seals during the winter breeding season. Of the 5,000, researchers said 1,350 seals were on the beach when the outbreak began. All public viewings of seals and seal tours are now closed.
Most of the adult females had already departed the beach for their routine migrations before the outbreak began, and most seals on the colony seem healthy.
“We are cautiously optimistic, as most of the adult females had already departed the beach for their routine migrations before the outbreak began, and most seals on the colony seem healthy,” said Roxanne Beltran, PhD, a professor in ecology and evolutionary biology at UC Santa Cruz.
Lancaster County, Pennsylvania hit again with bird flu
In other avian flu news, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has confirmed more H5N1 avian flu outbreaks on several commercial poultry sites this week.
In the last 30 days the virus has been confirmed in 56 flocks, including 30 commercial and 26 backyard flocks. A total of 9.65 million birds have been affected.
Lancaster County, Pennsylvania, has the largest outbreaks, with three in the past week, including 167,500 affected birds at a commercial broiler production facility. In Beadle County, South Dakota, a commercial turkey meat operation had 50,400 sickened birds.
APHIS also noted an outbreak in Lee County, South Carolina, at a commercial turkey meat plant with 36,400 birds and at a commercial table egg breeder in Pottawatomie County, Kansas, affecting 24,000 birds.
