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 new study. The strain, called COUG, has never been detected on California's coast before and is assumed to be a recent arrival. The researchers expressed concerns about potential contamination of the environment and the marine food chain, warning that such circumstances could pose a public health risk. No infections have been reported in humans so far.