Scientists: Unusual parasite killed sea otters off California coast
LOS ANGELES — Four sea otters that washed ashore on the California coast died from an unusual parasite that scientists warn could possibly infect other marine wildlife and humans.
There are currently no known infections of the Toxoplasma gondii strain among humans, according to a study published Wednesday from the California Department of Fish and Wildlife and UC Davis.
But the microscopic parasite could infect any warm-blooded animal or find its way into the food chain, the study said. That includes marine animals like mussels, clams, oysters, and crabs that are consumed raw or undercooked, corresponding study author Melissa Miller with the California Department of Fish and Wildlife said in a written statement.
“I have studied Toxoplasma infections in sea otters for 25 years, and I have never seen such severe lesions or high parasite numbers,” Miller said of the dead otters. “We are reporting our preliminary findings to alert others about this concerning condition.”
Otters are especially susceptible to
Toxoplasma infection, researchers said, because they find food along the shoreline and could be exposed to the parasite’s eggs in rainwater runoff as they feed on marine invertebrates. Typically, the parasite is found in wild and domestic cats and shed through their feces, according to the study authors.
The parasite strain, dubbed the COUG genotype, was first isolated in the wild from a mountain lion in British Columbia during an investigation of the parasite’s outbreak in humans in 1995 and a feral pig in eastern California, according to the study authors. The Canadian government reported there were 110 acute human infections identified and none were fatal.
The COUG genotype was present in all four otters, the study said.
The first otter washed ashore in San Simeon in San Luis Obispo County in February 2020, according to the study. The adult female otter was still alive, but thin, unresponsive and groaning. The other three otters washed ashore already dead during February and March 2022 in Cayucos in San Luis Obispo County and in Natural Bridges State Beach in Santa Cruz County, researchers said.