Two more juvenile dolphins have been found dead off the South Australian coast, as tests confirm others have died from a virus not previously detected in the state.

Five dolphins, found dead in Gulf St Vincent in the past six weeks, have now been confirmed as having morbillivirus.

Since March 1, 31 dead dolphins have been found on the SA coastline - 26 in Gulf St Vincent, three in Spencer Gulf and two in the south-east.

Department of Environment, Water and Natural Resources chief executive Allan Holmes said the figures included two found over the weekend.

"Morbillivirus can be spread through close contact between dolphins, including between mother and newborn," he said in a statement.

"The virus cannot be passed on to humans and it is unlikely that it would be able to survive in the environment, outside an animal, for any significant length of time."

Dolphin morbillivirus (DMV) has previously been implicated in the death of juvenile dolphins in Queensland, northern NSW and Western Australia.

Mr Holmes said several thousand dolphins lived in Gulf St Vincent, so the conservation status of the species was not under threat.