Rare parasite strain responsible for California sea otter deaths.

A rare strain of the microscopic parasite Toxoplasma gondii is killing California sea otters, posing a potential public health threat to other marine animals and humans, according to a study. The strain, called COUG, has never been detected on California's coast before, and researchers are concerned about potential contamination of the environment and the marine food chain. No infections have been reported in humans yet. Sea otters are vulnerable to Toxoplasma infection because they live near the coastline and can be exposed to the parasite's eggs through storm runoff and by eating marine invertebrates that can concentrate the parasites.