Sea otters and seals in the Pacific Ocean, off the coast of Alaska, are infected with a virus that once was seen only in animals in the Atlantic.

A new study suggests that melting ice in the Arctic may be to blame — and that climate change may help spread the disease to new areas and new animals.

Tracey Goldstein, a biologist at the University of California, Davis, got curious when sea otters in the Pacific tested positive for phocine distemper virus — a cousin of canine distemper virus — in 2004, two years after a major outbreak among European harbor seals.

Genetic analysis showed that the infections in the two groups were connected. Dr. Goldstein wondered how a virus usually passed through direct contact with a sick animal had managed to get from one northern ocean to another.