The carcasses of infected minks may have triggered a deadly viral outbreak that has killed thousands of seals in northern Europe, a Swedish scientist said Friday.

The phocine distemper virus, which wiped out half the region's seal population 14 years ago, reappeared this spring in Denmark and now has been confirmed in Sweden, Norway, Germany and the Netherlands.

Scientists have not determined the cause of the latest outbreak, but Swedish marine biologist Martin Larsvik said the disease may have spread from minks that were immune to the virus.

"Minks live in the same environment," Larsvik said. "They live on (the Danish island) Anholt, where the mass death started. If a dead mink is in the water, then seals are likely to come up and poke it and play with it."

Larsvik said more than 2,500 seal carcasses have washed up on beaches in Sweden. The epidemic likely will kill about half of the 19,000 seals in Sweden and Denmark, he said.

"We've established contact with mink hunters. We're going to test the animals so we can analyze the occurrence of phocine distemper virus," he said.

The virus, which does not affect humans, spreads through direct contact with body fluids or by scratching, clawing or biting. It usually causes severely matted eyes, runny noses and pneumonia.