diseased currants

Having recently dicovered some currants growing in my garden (red, white and black) I had cleared some of the surrounding plants to give them a little more space and light.

However, in the week since I've done this, something seems to have attcaked my currants :cry:

The fruit had already been taken by birds or fallen off but the pest/disease has left small holes in all the leaves (not bitten at the edges so much as small holes all over the leaf surface, holes have brown edges) and a large majority of the leaves are shrinking and severely yellowing.

I can't see any immediate signs of slug trails or insects on the leaves.

What could it be? And what should I do about it?

Any help appreciated. Bitsy