A rare parasite is killing California sea otters – is cat poop runoff to blame?

The distribution of the parasite in the bodies of the dead sea otters suggests that they died very quickly. Photograph: Niebrugge Images/Alamy

Scientist Melissa Miller was seeing something in California sea otters that she had not seen before: an unusually severe form of toxoplasmosis, which officials have confirmed has killed at least four of the animals.

“We wanted to get the word out. We’re seeing something we haven’t seen before, we want people to know about it and we want people working on marine mammals to be aware of these weird findings,” said Miller, a wildlife veterinarian specialist with the California department of fish and wildlife (DFW). “Take extra precautions.”