Deadly parasite threatens California sea otters

Melissa Miller knew something was off when she began to examine a sea otter that had died in San Simeon, a coastal California town about halfway between San Francisco and Los Angeles, in the winter of 2020. Nearly all of the animal’s body fat was inflamed. “It felt like there were little bumps all through it,” she says—a condition the veterinary pathologist had never seen in her 25 years examining sea otters for the California Department of Fish and Wildlife. She also found unusual lesions in the pancreas and heart. When Miller looked at the sea otter’s tissues under a microscope, she spotted a familiar foe: Toxoplasma gondii , the parasite that causes toxoplasmosis. But this strain wasn’t acting like the usual Toxoplasma , which typically causes mainly brain and heart inflammation in immune-suppressed animals, and is far less lethal. The San Simeon sea otter, in contrast, had very few parasites in its central nervous system, which suggests it died quickly of an acute infection before the parasite could extensively invade its brain. Since then, several more sea otters have been found dead on California beaches, all with similar lesions—and all harboring this troubling new strain of toxoplasmosis. “My concern is pretty high,” says Andrew Johnson, a sea otter conservationist with Defenders of Wildlife, who was not involved in the new study. “Sea otters have so many things that they’re struggling against.” A deadly ne...
Source: ScienceNOW - Category: Science Source Type: news